Python学习-数据类型！

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Python学习-数据类型！

1：Python的创始人

Python （英国发音：/ˈpaɪθən/ 美国发音：/ˈpaɪθɑːn/）, 是一种解释型、面向对象、动态数据类型的高级程序设计语言，由荷兰人Guido van Rossum于1989年发明，第一个公开发行版发行于1991年。

python的创始人为吉多·范罗苏姆（Guido van Rossum）。1989年的圣诞节期间，吉多·范罗苏姆为了在阿姆斯特丹打发时间，决心开发一个新的脚本解释程序，作为ABC语言的一种继承。

Python社区的人赋予他“仁慈大君” 的称号，这一称号直接来自英国肥皂剧《Monty Python飞行马戏团》。Guido当初之所以选中Python作为语言的名字，是因为他太喜欢这部肥皂剧了。

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2：Python的基本数据类型

 

数字

  • int（整型）
    1. 在32位机器上，整数的位数为32位，取值范围为-2**31～2**31-1，即-2147483648～2147483647
    1. 在64位系统上，整数的位数为64位，取值范围为-2**63～2**63-1，即-9223372036854775808～9223372036854775807
  • long（长整型） – python3 中已经将该类型取消
    1. 跟C语言不同，Python的长整数没有指定位宽，即：Python没有限制长整数数值的大小，但实际上由于机器内存有限，我们使用的长整数数值不可能无限大。
    1. 注意，自从Python2.2起，如果整数发生溢出，Python会自动将整数数据转换为长整数，所以如今在长整数数据后面不加字母L也不会导致严重后果了。
  • float（浮点型）
    1. 浮点数用来处理实数，即带有小数的数字。类似于C语言中的double类型，占8个字节（64位），其中52位表示底，11位表示指数，剩下的一位表示符号。
  • complex（复数）
    1. 复数由实数部分和虚数部分组成，一般形式为x＋yj，其中的x是复数的实数部分，y是复数的虚数部分，这里的x和y都是实数。
    1. 注：Python中存在小数字池：-5 ～ 257

布尔值

  • 真或假
    1. 1 或 0
    1. True 或 False

字符串

    1. "hello world"
  • 万恶的字符串拼接
    1. python中的字符串在C语言中体现为是一个字符数组，每次创建字符串时候需要在内存中开辟一块连续的空，并且一旦需要修改字符串的话，就需要再次开辟空间，万恶的+号每出现一次就会在内从中重新开辟一块空间。
  • 字符串格式化
    1. name = "zhangcong"
    1. print "i am %s " % name
    1. # 输出
    1. i am zhangcong
  • 字符串常用功能：
    • strip() # 去掉字符串首尾空格、换行符、tab
        1. value = " my name is zhangcong "
        1. print(value.strip()) # 会将首尾的空格去掉
        1. # 输出
        1. my name is zhangcong
    • split() # 通过指定分隔符对字符串进行切片，得到一个列表
        1. names = "zhangsan, lisi, wangwu"
        1. name2 = names.split(",")
        1. print(name2)
        1. # 输出
        1. ['zhangsan', ' lisi', ' wangwu']
    • center() # 返回一个原字符串居中,并使用空格填充至长度 width 的新字符串。默认填充字符为空格。
        1. 例1：
        1. value = "my name is zhangcong"
        1. print(value.center(50))
        1. # 输出
        1. my name is zhangcong
        1. 例2：
        1. # 使用*填充空格
        1. value = "my name is zhangcong"
        1. print(value.center(50, '*'))
        1. # 输出
        1. ***************my name is zhangcong***************
    • find() # 字符串查找
        1. 例1：
        1. # 在字符串value中查找字符串"zhangcong"是否存在，如果存在返回其下标值
        1. value = "my name is zhangcong"
        1. print(value.find("zhang"))
        1. # 输出
        1. 11
        1. -
        1. 例2：
        1. # 指定开始的位置查找
        1. value = "my name is zhangcong, my name is zhangcong"
        1. print(value.find("zhang", 12))
        1. # 输出
        1. 33
    • capitalize() # 首字母大写，没什么卵用
        1. value = "my name is zhangcong, my name is zhangcong"
        1. print(value.capitalize())
        1. # 输出
        1. My name is zhangcong, my name is zhangcong
    • upper() # 将字符串里面的所有字母都改为大写
        1. value = "43 fd"
        1. print(value.upper())
        1. # 输出
        1. 43 FD
    • format() 格式化字符串
        1. value = "my name is {}"
        1. print(value.format("zhangcong"))
        1. # 输出
        1. my name is zhangcong
    • isdigit() # 判断字符串是否是数字类型 返回True 或 False
        1. 例1：
        1. value = "my name is {}"
        1. print(value.isdigit())
        1. # 输出
        1. False
        1. -
        1. 例2：
        1. num_str = "1000"
        1. print(num_str.isdigit())
        1. # 输出
        1. True
    • isalnum() # 判断字符是否只含有字母和数字组成 返回True 或 False
        1. 例1：
        1. value = "43fd"
        1. print(value.isalnum())
        1. # 输出
        1. True
        1. -
        1. 例2：
        1. # value中包含一个空格
        1. value = "43 fd"
        1. print(value.isalnum())
        1. # 输出
        1. False
    • endswith() # 匹配字符串的结束位置，返回True 或 False
        1. value = "43 fd"
        1. print(value.endswith("fd"))
        1. # 输出
        1. True
        1. -
        1. print(value.endswith("c"))
        1. # 输出
        1. False
    • startswith() # 匹配字符串的开始位置，返回True 或 False
        1. value = "43 fd"
        1. print(value.startswith("4"))
        1. # 输出
        1. True
        1. -
        1. print(value.startswith("fda"))
        1. # 输出
        1. False

列表

    1. # 创建列表
    1. name_list = ["zhangsan", "lisi", "wangwu"]
    1. 或
    1. name_list = list(["zhangsan", "lisi", "wangwu"])
    1. # 通过列表的下标来取对应的值
    1. print(name_list[1])
    1. # 输出
    1. lisi
  • 列表常用功能
    • 修改列表中的值
        1. # 将name_list中的 "lisi" 修改为 "liwu"
        1. name_list = ["zhangsan", "lisi", "wangwu"]
        1. name_list[1] = "liwu" # 指定下标修改列表的值
        1. print(name_list)
        1. # 输出
        1. ['zhangsan', 'liwu', 'wangwu']
    • 切片
        1. # 输出name_list中的第一个值和第二个值
        1. name_list = ["zhangsan", "lisi", "wangwu", 1, 2, 3, 4, 5]
        1. print(name_list[1:3]) # 顾头不顾尾
        1. # 输出
        1. ['lisi', 'wangwu']
    • 步长
        1. # 首先创建一个从0到100的列表，不包含100
        1. num_list = list(range(100))
        1. print(num_list[::2])
        1. # 输出
        1. [0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98]
        1. # 注：通过步长可以取奇偶数
    • insert() # 指定坐标插入值
        1. # 在列表name_list的值"lisi"前面插入一个值"xiaogou"
        1. name_list = ["zhangsan", "lisi", "wangwu"]
        1. name_list.insert(1, "xiaogou")
        1. print(name_list)
        1. # 输出
        1. ['zhangsan', 'xiaogou', 'lisi', 'wangwu']
    • append() # 在列表的末尾追加一个值
        1. name_list = ["zhangsan", "lisi", "wangwu"]
        1. name_list.append("xiaogou")
        1. print(name_list)
        1. # 输出
        1. ['zhangsan', 'lisi', 'wangwu', 'xiaogou']
    • remove() # 删除列表中的指定值
        1. name_list = ["zhangsan", "lisi", "wangwu"]
        1. name_list.remove("lisi")
        1. print(name_list)
        1. # 输出
        1. ['zhangsan', 'wangwu']
        1. # 如果删除的值不在列表中，则会报错
        1. name_list = ["zhangsan", "lisi", "wangwu"]
        1. name_list.remove("lisfdi")
        1. print(name_list)
        1. # 输出报错信息
        1. ValueError: list.remove(x): x not in list
    • count() # 查找在列表中出现的次数
        1. name_list = ["zhangsan", "lisi", "wangwu", "lisi", 1, 2, 3, 4, 5]
        1. print(name_list.count("lisi")) # 查找"lisi"在列表中出现的次数
        1. # 输出
        1. 2
    • index() # 查找在列表中的下标
        1. name_list = ["zhangsan", "lisi", "wangwu", "lisi", 1, 2, 3, 4, 5]
        1. print(name_list.index("lisi"))
        1. # 输出
        1. 1
        1. -
        1. # 如果查找的值在列表中不存在，则会报错
        1. name_list = ["zhangsan", "lisi", "wangwu", "lisi", 1, 2, 3, 4, 5]
        1. print(name_list.index("lisi2"))
        1. # 输出报错信息
        1. ValueError: 'lisi2' is not in list
    • extend() # 在原先列表的基础之上扩展一个新的列表
        1. name_list = ["zhangsan", "lisi", "wangwu", "lisi"]
        1. name_list2 = [1, 2, 3, 4, 5]
        1. name_list.extend(name_list2)
        1. print(name_list)
        1. # 输出
        1. ['zhangsan', 'lisi', 'wangwu', 'lisi', 1, 2, 3, 4, 5]
    • reverse() # 将列表的值进行反转
        1. name_list = ['zhangsan', 'lisi', 'wangwu', 'lisi', 1, 2, 3, 4, 5]
        1. name_list.reverse()
        1. print(name_list)
        1. # 输出
        1. [5, 4, 3, 2, 1, 'lisi', 'wangwu', 'lisi', 'zhangsan']
    • sort() # 排序
        1. # 在python3中，列表中的值同时存在字符串和数字时排序是会报错的，在python2中是没有问题的，python2中是按照ascll编码顺序进行排序的
        1. name_list = ['zhangsan', 'lisi', 'wangwu', 'lisi', 1, 2, 3, 4, 5]
        1. name_list.sort()
        1. # 输错报错信息
        1. TypeError: unorderable types: int() < str()
        1. -
        1. # 对字母进行排序
        1. name_list = ['zhangsan', 'lisi', 'wangwu', 'lisi']
        1. name_list.sort()
        1. print(name_list)
        1. # 输出
        1. ['lisi', 'lisi', 'wangwu', 'zhangsan']
        1. -
        1. # 对数字进行排序
        1. num_list = [3, 4, 1, 100, 3, 5, 6]
        1. num_list.sort()
        1. print(num_list)
        1. # 输出
        1. [1, 3, 3, 4, 5, 6, 100]
    • pop() # 默认删除列表最后的一个值，并返回删掉的那个值
        1. name_list = ['zhangsan', 'lisi', 'wangwu', 'lisi', '44']
        1. pop_name = name_list.pop()
        1. print(name_list)
        1. print(pop_name)
        1. # 输出
        1. ['zhangsan', 'lisi', 'wangwu', 'lisi']
        1. 44
        1. -
        1. # 指定下标删除列表元素
        1. name_list = ['zhangsan', 'lisi', 'wangwu', 'lisi', '44']
        1. pop_name = name_list.pop(2)
        1. print(name_list)
        1. print(pop_name)
        1. # 输出
        1. ['zhangsan', 'lisi', 'lisi', '44']
        1. wangwu
    • copy() # 浅拷贝 可以通过id()查看内存地址看区别
        1. name_list = ['zhangsan', 'lisi', 'wangwu', 'lisi', '44']
        1. name_list2 = name_list.copy()
        1. print("name_list: %s" % name_list)
        1. print("name_list2: %s" % name_list2)
        1. # 将name_list中的'zhangsan'改为'liusan'
        1. name_list[0] = 'liusan'
        1. print("修改完之后")
        1. print("name_list: %s" % name_list)
        1. print("name_list2: %s" % name_list2)
        1. # 输出
        1. name_list: ['zhangsan', 'lisi', 'wangwu', 'lisi', '44']
        1. name_list2: ['zhangsan', 'lisi', 'wangwu', 'lisi', '44']
        1. 修改完之后
        1. name_list: ['liusan', 'lisi', 'wangwu', 'lisi', '44']
        1. name_list2: ['zhangsan', 'lisi', 'wangwu', 'lisi', '44']
        1. -
        1. # 在name_list中嵌套一个列表，然后拷贝一份，然后在修改嵌套列表中的值
        1. name_list = ['zhangsan', 'lisi', 'wangwu', 'lisi', '44', [3, 4, 1, 100, 3, 5, 6]]
        1. name_list2 = name_list.copy()
        1. print("name_list: %s" % name_list)
        1. print("name_list2: %s" % name_list2)
        1. # 将name_list中的'zhangsan'改为'liusan'
        1. name_list[-1][0] = 'liusan'
        1. print("修改完之后")
        1. print("name_list: %s" % name_list)
        1. print("name_list2: %s" % name_list2)
        1. # 输出
        1. # 可以看到name_list中嵌套列表中的值被修改，name_list2也随着变化，浅拷贝只能操作第一层
        1. name_list: ['zhangsan', 'lisi', 'wangwu', 'lisi', '44', [3, 4, 1, 100, 3, 5, 6]]
        1. name_list2: ['zhangsan', 'lisi', 'wangwu', 'lisi', '44', [3, 4, 1, 100, 3, 5, 6]]
        1. 修改完之后
        1. name_list: ['zhangsan', 'lisi', 'wangwu', 'lisi', '44', ['liusan', 4, 1, 100, 3, 5, 6]]
        1. name_list2: ['zhangsan', 'lisi', 'wangwu', 'lisi', '44', ['liusan', 4, 1, 100, 3, 5, 6]]
        1. # 浅拷贝与=之间的区别，等于号相当于软连接，浅拷贝类似于上面

字典

  • 创建字典
    1. # 字典是以key和value的形式出现的
    1. id_db = {
    1. 22323232: {
    1. "name": "ShanPao",
    1. "age": 22,
    1. "addr": "ShanDong"
    1. },
    1. 43267432:{
    1. "name": "DaShanPao",
    1. "age": 24,
    1. "addr": "DongBei"
    1. }
    1. }
    1. # 输出字典中key为id_db[22323232]的值
    1. print(id_db[22323232])
    1. # 修改字典中key为22323232的key "name"的值
    1. id_db[22323232]["name"] = "Wangwu"
    1. print(id_db)
    1. # 输出
    1. {'age': 22, 'addr': 'ShanDong', 'name': 'ShanPao'}
    1. {22323232: {'age': 22, 'addr': 'ShanDong', 'name': 'Wangwu'}, 43267432: {'age': 24, 'addr': 'DongBei', 'name': 'DaShanPao'}}
  • 字典常用功能
    • pop() # 对指定key进行删除,并返回其value
        1. id_db = {
        1. 22323232: {
        1. "name": "ShanPao",
        1. "age": 22,
        1. "addr": "ShanDong"
        1. },
        1. 43267432:{
        1. "name": "DaShanPao",
        1. "age": 24,
        1. "addr": "DongBei"
        1. }
        1. }
        1. print(id_db)
        1. v = id_db.pop(43267432)
        1. print(v)
        1. print(id_db)
        1. # 输出
        1. # 字典id_db的值
        1. {22323232: {'age': 22, 'addr': 'ShanDong', 'name': 'ShanPao'}, 43267432: {'age': 24, 'addr': 'DongBei', 'name': 'DaShanPao'}}
        1. # 通过pop()删除的值
        1. {'age': 24, 'addr': 'DongBei', 'name': 'DaShanPao'}
        1. # 通过pop()删除之后的值
        1. {22323232: {'age': 22, 'addr': 'ShanDong', 'name': 'ShanPao'}}
    • get() # 通过key获取值
        1. id_db = {
        1. 22323232: {
        1. "name": "ShanPao",
        1. "age": 22,
        1. "addr": "ShanDong"
        1. },
        1. 43267432:{
        1. "name": "DaShanPao",
        1. "age": 24,
        1. "addr": "DongBei"
        1. }
        1. }
        1. print(id_db.get(43267432))
        1. # 输出
        1. {'age': 24, 'name': 'DaShanPao', 'addr': 'DongBei'}
    • update() # 对已经存在的key进行更新，没有的key进行添加
        1. id_db = {
        1. 22323232: {
        1. "name": "ShanPao",
        1. "age": 22,
        1. "addr": "ShanDong"
        1. },
        1. 43267432:{
        1. "name": "DaShanPao",
        1. "age": 24,
        1. "addr": "DongBei"
        1. }
        1. }
        1. dic2 = {
        1. 22323232: {
        1. "name": "DaShaXXXXXXX",
        1. "age": 22,
        1. "addr": "ShanDong"
        1. },
        1. "name": "acong",
        1. 43267432: "xxxxxx"
        1. }
        1. print(id_db)
        1. id_db.update(dic2)
        1. print(id_db)
        1. # 输出
        1. {22323232: {'addr': 'ShanDong', 'name': 'ShanPao', 'age': 22}, 43267432: {'addr': 'DongBei', 'name': 'DaShanPao', 'age': 24}}
        1. {22323232: {'addr': 'ShanDong', 'name': 'DaShaXXXXXXX', 'age': 22}, 43267432: 'xxxxxx', 'name': 'acong'}
    • items() # 将字典的key和value放到一个元组中，多组key和value放入到到一个列表中，转成这种格式： [(key, value), (key, value)]
        1. id_db = {
        1. 22323232: {
        1. "name": "ShanPao",
        1. "age": 22,
        1. "addr": "ShanDong"
        1. },
        1. 43267432:{
        1. "name": "DaShanPao",
        1. "age": 24,
        1. "addr": "DongBei"
        1. }
        1. }
        1. print(id_db.items())
        1. # 输出
        1. dict_items([(22323232, {'age': 22, 'addr': 'ShanDong', 'name': 'ShanPao'}), (43267432, {'age': 24, 'addr': 'DongBei', 'name': 'DaShanPao'})])
    • keys() # 输出字典所有的key
        1. id_db = {
        1. 22323232: {
        1. "name": "ShanPao",
        1. "age": 22,
        1. "addr": "ShanDong"
        1. },
        1. 43267432:{
        1. "name": "DaShanPao",
        1. "age": 24,
        1. "addr": "DongBei"
        1. }
        1. }
        1. print(id_db.keys())
        1. # 输出
        1. dict_keys([22323232, 43267432])
    • values() # 输出字典所有的value
        1. id_db = {
        1. 22323232: {
        1. "name": "ShanPao",
        1. "age": 22,
        1. "addr": "ShanDong"
        1. },
        1. 43267432:{
        1. "name": "DaShanPao",
        1. "age": 24,
        1. "addr": "DongBei"
        1. }
        1. }
        1. print(id_db.values())
        1. # 输出
        1. dict_values([{'name': 'ShanPao', 'addr': 'ShanDong', 'age': 22}, {'name': 'DaShanPao', 'addr': 'DongBei', 'age': 24}])
    • has_key() # 查找key是否在字典中存在，只能在python2里面使用，python3使用in判断
    • setdefault() # 指定一个key，如果字典存在这个key，则返回该key的值，否则创建这个key，如果setdefault()括号内为空，则创建的key的value 为None，否则为该括号内填写的值
        1. id_db = {
        1. 22323232: {
        1. "name": "ShanPao",
        1. "age": 22,
        1. "addr": "ShanDong"
        1. },
        1. 43267432:{
        1. "name": "DaShanPao",
        1. "age": 24,
        1. "addr": "DongBei"
        1. }
        1. }
        1. value = id_db.setdefault(43267432)
        1. print(value)
        1. value2 = id_db.setdefault(432674323232)
        1. print(value2)
        1. print(id_db)
        1. # 输出
        1. {'addr': 'DongBei', 'name': 'DaShanPao', 'age': 24}
        1. None
        1. {22323232: {'addr': 'ShanDong', 'name': 'ShanPao', 'age': 22}, 43267432: {'addr': 'DongBei', 'name': 'DaShanPao', 'age': 24}, 432674323232: None}
    • popitem() # 随机删除字典中的指定的key
        1. id_db = {
        1. 22323232: {
        1. "name": "ShanPao",
        1. "age": 22,
        1. "addr": "ShanDong"
        1. },
        1. 43267432:{
        1. "name": "DaShanPao",
        1. "age": 24,
        1. "addr": "DongBei"
        1. }
        1. }
        1. print(id_db.popitem())
        1. print(id_db)
        1. # 输出
        1. (22323232, {'age': 22, 'addr': 'ShanDong', 'name': 'ShanPao'})
        1. {43267432: {'age': 24, 'addr': 'DongBei', 'name': 'DaShanPao'}}

 

一：数字 int

int(整型)：

在32位机器上，整数的位数为32位，取值范围为-2**31～2**31-1，即-2147483648～2147483647
在64位系统上，整数的位数为64位，取值范围为-2**63～2**63-1，即-9223372036854775808～9223372036854775807

long（长整型）：

跟C语言不同，Python的长整数没有指定位宽，即：Python没有限制长整数数值的大小，但实际上由于机器内存有限，我们使用的长整数数值不可能无限大

注意：自从python2.2起，如果整数发生溢出，python会自动将整数数据转换为长整数，所以如今在长整数数据后面不加字母L也不会导致严重后果了

float（浮点型）：

浮点数用来处理实数，即带有小数的数字，类似于C语言中的double类型，占8个字节（64位），其中52位表示底，11位表示指数，剩下一位表示符号

  1. class int(object):
  2. """
  3. int(x=0) -> int or long
  4. int(x, base=10) -> int or long
  5.  
  6. Convert a number or string to an integer, or return 0 if no arguments
  7. are given. If x is floating point, the conversion truncates towards zero.
  8. If x is outside the integer range, the function returns a long instead.
  9.  
  10. If x is not a number or if base is given, then x must be a string or
  11. Unicode object representing an integer literal in the given base. The
  12. literal can be preceded by '+' or '-' and be surrounded by whitespace.
  13. The base defaults to 10. Valid bases are 0 and 2-36. Base 0 means to
  14. interpret the base from the string as an integer literal.
  15. >>> int('0b100', base=0)
  16. """
  17. def bit_length(self):
  18. """ 返回表示该数字的时占用的最少位数 """
  19. """
  20. int.bit_length() -> int
  21.  
  22. Number of bits necessary to represent self in binary.
  23. >>> bin(37)
  24. '0b100101'
  25. >>> (37).bit_length()
  26. """
  27. return 0
  28.  
  29. def conjugate(self, *args, **kwargs): # real signature unknown
  30. """ 返回该复数的共轭复数 """
  31. """ Returns self, the complex conjugate of any int. """
  32. pass
  33.  
  34. def __abs__(self):
  35. """ 返回绝对值 """
  36. """ x.__abs__() <==> abs(x) """
  37. pass
  38.  
  39. def __add__(self, y):
  40. """ x.__add__(y) <==> x+y """
  41. pass
  42.  
  43. def __and__(self, y):
  44. """ x.__and__(y) <==> x&y """
  45. pass
  46.  
  47. def __cmp__(self, y):
  48. """ 比较两个数大小 """
  49. """ x.__cmp__(y) <==> cmp(x,y) """
  50. pass
  51.  
  52. def __coerce__(self, y):
  53. """ 强制生成一个元组 """
  54. """ x.__coerce__(y) <==> coerce(x, y) """
  55. pass
  56.  
  57. def __divmod__(self, y):
  58. """ 相除，得到商和余数组成的元组 """
  59. """ x.__divmod__(y) <==> divmod(x, y) """
  60. pass
  61.  
  62. def __div__(self, y):
  63. """ x.__div__(y) <==> x/y """
  64. pass
  65.  
  66. def __float__(self):
  67. """ 转换为浮点类型 """
  68. """ x.__float__() <==> float(x) """
  69. pass
  70.  
  71. def __floordiv__(self, y):
  72. """ x.__floordiv__(y) <==> x//y """
  73. pass
  74.  
  75. def __format__(self, *args, **kwargs): # real signature unknown
  76. pass
  77.  
  78. def __getattribute__(self, name):
  79. """ x.__getattribute__('name') <==> x.name """
  80. pass
  81.  
  82. def __getnewargs__(self, *args, **kwargs): # real signature unknown
  83. """ 内部调用 __new__方法或创建对象时传入参数使用 """
  84. pass
  85.  
  86. def __hash__(self):
  87. """如果对象object为哈希表类型，返回对象object的哈希值。哈希值为整数。在字典查找中，哈希值用于快速比较字典的键。两个数值如果相等，则哈希值也相等。"""
  88. """ x.__hash__() <==> hash(x) """
  89. pass
  90.  
  91. def __hex__(self):
  92. """ 返回当前数的 十六进制 表示 """
  93. """ x.__hex__() <==> hex(x) """
  94. pass
  95.  
  96. def __index__(self):
  97. """ 用于切片，数字无意义 """
  98. """ x[y:z] <==> x[y.__index__():z.__index__()] """
  99. pass
  100.  
  101. def __init__(self, x, base=10): # known special case of int.__init__
  102. """ 构造方法，执行 x = 123 或 x = int(10) 时，自动调用，暂时忽略 """
  103. """
  104. int(x=0) -> int or long
  105. int(x, base=10) -> int or long
  106.  
  107. Convert a number or string to an integer, or return 0 if no arguments
  108. are given. If x is floating point, the conversion truncates towards zero.
  109. If x is outside the integer range, the function returns a long instead.
  110.  
  111. If x is not a number or if base is given, then x must be a string or
  112. Unicode object representing an integer literal in the given base. The
  113. literal can be preceded by '+' or '-' and be surrounded by whitespace.
  114. The base defaults to 10. Valid bases are 0 and 2-36. Base 0 means to
  115. interpret the base from the string as an integer literal.
  116. >>> int('0b100', base=0)
  117. # (copied from class doc)
  118. """
  119. pass
  120.  
  121. def __int__(self):
  122. """ 转换为整数 """
  123. """ x.__int__() <==> int(x) """
  124. pass
  125.  
  126. def __invert__(self):
  127. """ x.__invert__() <==> ~x """
  128. pass
  129.  
  130. def __long__(self):
  131. """ 转换为长整数 """
  132. """ x.__long__() <==> long(x) """
  133. pass
  134.  
  135. def __lshift__(self, y):
  136. """ x.__lshift__(y) <==> x<<y """
  137. pass
  138.  
  139. def __mod__(self, y):
  140. """ x.__mod__(y) <==> x%y """
  141. pass
  142.  
  143. def __mul__(self, y):
  144. """ x.__mul__(y) <==> x*y """
  145. pass
  146.  
  147. def __neg__(self):
  148. """ x.__neg__() <==> -x """
  149. pass
  150.  
  151. @staticmethod # known case of __new__
  152. def __new__(S, *more):
  153. """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
  154. pass
  155.  
  156. def __nonzero__(self):
  157. """ x.__nonzero__() <==> x != 0 """
  158. pass
  159.  
  160. def __oct__(self):
  161. """ 返回改值的 八进制 表示 """
  162. """ x.__oct__() <==> oct(x) """
  163. pass
  164.  
  165. def __or__(self, y):
  166. """ x.__or__(y) <==> x|y """
  167. pass
  168.  
  169. def __pos__(self):
  170. """ x.__pos__() <==> +x """
  171. pass
  172.  
  173. def __pow__(self, y, z=None):
  174. """ 幂，次方 """
  175. """ x.__pow__(y[, z]) <==> pow(x, y[, z]) """
  176. pass
  177.  
  178. def __radd__(self, y):
  179. """ x.__radd__(y) <==> y+x """
  180. pass
  181.  
  182. def __rand__(self, y):
  183. """ x.__rand__(y) <==> y&x """
  184. pass
  185.  
  186. def __rdivmod__(self, y):
  187. """ x.__rdivmod__(y) <==> divmod(y, x) """
  188. pass
  189.  
  190. def __rdiv__(self, y):
  191. """ x.__rdiv__(y) <==> y/x """
  192. pass
  193.  
  194. def __repr__(self):
  195. """转化为解释器可读取的形式 """
  196. """ x.__repr__() <==> repr(x) """
  197. pass
  198.  
  199. def __str__(self):
  200. """转换为人阅读的形式，如果没有适于人阅读的解释形式的话，则返回解释器课阅读的形式"""
  201. """ x.__str__() <==> str(x) """
  202. pass
  203.  
  204. def __rfloordiv__(self, y):
  205. """ x.__rfloordiv__(y) <==> y//x """
  206. pass
  207.  
  208. def __rlshift__(self, y):
  209. """ x.__rlshift__(y) <==> y<<x """
  210. pass
  211.  
  212. def __rmod__(self, y):
  213. """ x.__rmod__(y) <==> y%x """
  214. pass
  215.  
  216. def __rmul__(self, y):
  217. """ x.__rmul__(y) <==> y*x """
  218. pass
  219.  
  220. def __ror__(self, y):
  221. """ x.__ror__(y) <==> y|x """
  222. pass
  223.  
  224. def __rpow__(self, x, z=None):
  225. """ y.__rpow__(x[, z]) <==> pow(x, y[, z]) """
  226. pass
  227.  
  228. def __rrshift__(self, y):
  229. """ x.__rrshift__(y) <==> y>>x """
  230. pass
  231.  
  232. def __rshift__(self, y):
  233. """ x.__rshift__(y) <==> x>>y """
  234. pass
  235.  
  236. def __rsub__(self, y):
  237. """ x.__rsub__(y) <==> y-x """
  238. pass
  239.  
  240. def __rtruediv__(self, y):
  241. """ x.__rtruediv__(y) <==> y/x """
  242. pass
  243.  
  244. def __rxor__(self, y):
  245. """ x.__rxor__(y) <==> y^x """
  246. pass
  247.  
  248. def __sub__(self, y):
  249. """ x.__sub__(y) <==> x-y """
  250. pass
  251.  
  252. def __truediv__(self, y):
  253. """ x.__truediv__(y) <==> x/y """
  254. pass
  255.  
  256. def __trunc__(self, *args, **kwargs):
  257. """ 返回数值被截取为整形的值，在整形中无意义 """
  258. pass
  259.  
  260. def __xor__(self, y):
  261. """ x.__xor__(y) <==> x^y """
  262. pass
  263.  
  264. denominator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
  265. """ 分母 = 1 """
  266. """the denominator of a rational number in lowest terms"""
  267.  
  268. imag = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
  269. """ 虚数，无意义 """
  270. """the imaginary part of a complex number"""
  271.  
  272. numerator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
  273. """ 分子 = 数字大小 """
  274. """the numerator of a rational number in lowest terms"""
  275.  
  276. real = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
  277. """ 实属，无意义 """
  278. """the real part of a complex number"""
  279.  
  280. int

int

二：字符串 str

  1. class str(basestring):
  2. """
  3. str(object='') -> string
  4.  
  5. Return a nice string representation of the object.
  6. If the argument is a string, the return value is the same object.
  7. """
  8. def capitalize(self):
  9. """ 首字母变大写 """
  10. """
  11. S.capitalize() -> string
  12.  
  13. Return a copy of the string S with only its first character
  14. capitalized.
  15. """
  16. return ""
  17.  
  18. def center(self, width, fillchar=None):
  19. """ 内容居中，width：总长度；fillchar：空白处填充内容，默认无 """
  20. """
  21. S.center(width[, fillchar]) -> string
  22.  
  23. Return S centered in a string of length width. Padding is
  24. done using the specified fill character (default is a space)
  25. """
  26. return ""
  27.  
  28. def count(self, sub, start=None, end=None):
  29. """ 子序列个数 """
  30. """
  31. S.count(sub[, start[, end]]) -> int
  32.  
  33. Return the number of non-overlapping occurrences of substring sub in
  34. string S[start:end]. Optional arguments start and end are interpreted
  35. as in slice notation.
  36. """
  37. return 0
  38.  
  39. def decode(self, encoding=None, errors=None):
  40. """ 解码 """
  41. """
  42. S.decode([encoding[,errors]]) -> object
  43.  
  44. Decodes S using the codec registered for encoding. encoding defaults
  45. to the default encoding. errors may be given to set a different error
  46. handling scheme. Default is 'strict' meaning that encoding errors raise
  47. a UnicodeDecodeError. Other possible values are 'ignore' and 'replace'
  48. as well as any other name registered with codecs.register_error that is
  49. able to handle UnicodeDecodeErrors.
  50. """
  51. return object()
  52.  
  53. def encode(self, encoding=None, errors=None):
  54. """ 编码，针对unicode """
  55. """
  56. S.encode([encoding[,errors]]) -> object
  57.  
  58. Encodes S using the codec registered for encoding. encoding defaults
  59. to the default encoding. errors may be given to set a different error
  60. handling scheme. Default is 'strict' meaning that encoding errors raise
  61. a UnicodeEncodeError. Other possible values are 'ignore', 'replace' and
  62. 'xmlcharrefreplace' as well as any other name registered with
  63. codecs.register_error that is able to handle UnicodeEncodeErrors.
  64. """
  65. return object()
  66.  
  67. def endswith(self, suffix, start=None, end=None):
  68. """ 是否以 xxx 结束 """
  69. """
  70. S.endswith(suffix[, start[, end]]) -> bool
  71.  
  72. Return True if S ends with the specified suffix, False otherwise.
  73. With optional start, test S beginning at that position.
  74. With optional end, stop comparing S at that position.
  75. suffix can also be a tuple of strings to try.
  76. """
  77. return False
  78.  
  79. def expandtabs(self, tabsize=None):
  80. """ 将tab转换成空格，默认一个tab转换成8个空格 """
  81. """
  82. S.expandtabs([tabsize]) -> string
  83.  
  84. Return a copy of S where all tab characters are expanded using spaces.
  85. If tabsize is not given, a tab size of 8 characters is assumed.
  86. """
  87. return ""
  88.  
  89. def find(self, sub, start=None, end=None):
  90. """ 寻找子序列位置，如果没找到，返回 -1 """
  91. """
  92. S.find(sub [,start [,end]]) -> int
  93.  
  94. Return the lowest index in S where substring sub is found,
  95. such that sub is contained within S[start:end]. Optional
  96. arguments start and end are interpreted as in slice notation.
  97.  
  98. Return -1 on failure.
  99. """
  100. return 0
  101.  
  102. def format(*args, **kwargs): # known special case of str.format
  103. """ 字符串格式化，动态参数，将函数式编程时细说 """
  104. """
  105. S.format(*args, **kwargs) -> string
  106.  
  107. Return a formatted version of S, using substitutions from args and kwargs.
  108. The substitutions are identified by braces ('{' and '}').
  109. """
  110. pass
  111.  
  112. def index(self, sub, start=None, end=None):
  113. """ 子序列位置，如果没找到，报错 """
  114. S.index(sub [,start [,end]]) -> int
  115.  
  116. Like S.find() but raise ValueError when the substring is not found.
  117. """
  118. return 0
  119.  
  120. def isalnum(self):
  121. """ 是否是字母和数字 """
  122. """
  123. S.isalnum() -> bool
  124.  
  125. Return True if all characters in S are alphanumeric
  126. and there is at least one character in S, False otherwise.
  127. """
  128. return False
  129.  
  130. def isalpha(self):
  131. """ 是否是字母 """
  132. """
  133. S.isalpha() -> bool
  134.  
  135. Return True if all characters in S are alphabetic
  136. and there is at least one character in S, False otherwise.
  137. """
  138. return False
  139.  
  140. def isdigit(self):
  141. """ 是否是数字 """
  142. """
  143. S.isdigit() -> bool
  144.  
  145. Return True if all characters in S are digits
  146. and there is at least one character in S, False otherwise.
  147. """
  148. return False
  149.  
  150. def islower(self):
  151. """ 是否小写 """
  152. """
  153. S.islower() -> bool
  154.  
  155. Return True if all cased characters in S are lowercase and there is
  156. at least one cased character in S, False otherwise.
  157. """
  158. return False
  159.  
  160. def isspace(self):
  161. """
  162. S.isspace() -> bool
  163.  
  164. Return True if all characters in S are whitespace
  165. and there is at least one character in S, False otherwise.
  166. """
  167. return False
  168.  
  169. def istitle(self):
  170. """
  171. S.istitle() -> bool
  172.  
  173. Return True if S is a titlecased string and there is at least one
  174. character in S, i.e. uppercase characters may only follow uncased
  175. characters and lowercase characters only cased ones. Return False
  176. otherwise.
  177. """
  178. return False
  179.  
  180. def isupper(self):
  181. """
  182. S.isupper() -> bool
  183.  
  184. Return True if all cased characters in S are uppercase and there is
  185. at least one cased character in S, False otherwise.
  186. """
  187. return False
  188.  
  189. def join(self, iterable):
  190. """ 连接 """
  191. """
  192. S.join(iterable) -> string
  193.  
  194. Return a string which is the concatenation of the strings in the
  195. iterable. The separator between elements is S.
  196. """
  197. return ""
  198.  
  199. def ljust(self, width, fillchar=None):
  200. """ 内容左对齐，右侧填充 """
  201. """
  202. S.ljust(width[, fillchar]) -> string
  203.  
  204. Return S left-justified in a string of length width. Padding is
  205. done using the specified fill character (default is a space).
  206. """
  207. return ""
  208.  
  209. def lower(self):
  210. """ 变小写 """
  211. """
  212. S.lower() -> string
  213.  
  214. Return a copy of the string S converted to lowercase.
  215. """
  216. return ""
  217.  
  218. def lstrip(self, chars=None):
  219. """ 移除左侧空白 """
  220. """
  221. S.lstrip([chars]) -> string or unicode
  222.  
  223. Return a copy of the string S with leading whitespace removed.
  224. If chars is given and not None, remove characters in chars instead.
  225. If chars is unicode, S will be converted to unicode before stripping
  226. """
  227. return ""
  228.  
  229. def partition(self, sep):
  230. """ 分割，前，中，后三部分 """
  231. """
  232. S.partition(sep) -> (head, sep, tail)
  233.  
  234. Search for the separator sep in S, and return the part before it,
  235. the separator itself, and the part after it. If the separator is not
  236. found, return S and two empty strings.
  237. """
  238. pass
  239.  
  240. def replace(self, old, new, count=None):
  241. """ 替换 """
  242. """
  243. S.replace(old, new[, count]) -> string
  244.  
  245. Return a copy of string S with all occurrences of substring
  246. old replaced by new. If the optional argument count is
  247. given, only the first count occurrences are replaced.
  248. """
  249. return ""
  250.  
  251. def rfind(self, sub, start=None, end=None):
  252. """
  253. S.rfind(sub [,start [,end]]) -> int
  254.  
  255. Return the highest index in S where substring sub is found,
  256. such that sub is contained within S[start:end]. Optional
  257. arguments start and end are interpreted as in slice notation.
  258.  
  259. Return -1 on failure.
  260. """
  261. return 0
  262.  
  263. def rindex(self, sub, start=None, end=None):
  264. """
  265. S.rindex(sub [,start [,end]]) -> int
  266.  
  267. Like S.rfind() but raise ValueError when the substring is not found.
  268. """
  269. return 0
  270.  
  271. def rjust(self, width, fillchar=None):
  272. """
  273. S.rjust(width[, fillchar]) -> string
  274.  
  275. Return S right-justified in a string of length width. Padding is
  276. done using the specified fill character (default is a space)
  277. """
  278. return ""
  279.  
  280. def rpartition(self, sep):
  281. """
  282. S.rpartition(sep) -> (head, sep, tail)
  283.  
  284. Search for the separator sep in S, starting at the end of S, and return
  285. the part before it, the separator itself, and the part after it. If the
  286. separator is not found, return two empty strings and S.
  287. """
  288. pass
  289.  
  290. def rsplit(self, sep=None, maxsplit=None):
  291. """
  292. S.rsplit([sep [,maxsplit]]) -> list of strings
  293.  
  294. Return a list of the words in the string S, using sep as the
  295. delimiter string, starting at the end of the string and working
  296. to the front. If maxsplit is given, at most maxsplit splits are
  297. done. If sep is not specified or is None, any whitespace string
  298. is a separator.
  299. """
  300. return []
  301.  
  302. def rstrip(self, chars=None):
  303. """
  304. S.rstrip([chars]) -> string or unicode
  305.  
  306. Return a copy of the string S with trailing whitespace removed.
  307. If chars is given and not None, remove characters in chars instead.
  308. If chars is unicode, S will be converted to unicode before stripping
  309. """
  310. return ""
  311.  
  312. def split(self, sep=None, maxsplit=None):
  313. """ 分割， maxsplit最多分割几次 """
  314. """
  315. S.split([sep [,maxsplit]]) -> list of strings
  316.  
  317. Return a list of the words in the string S, using sep as the
  318. delimiter string. If maxsplit is given, at most maxsplit
  319. splits are done. If sep is not specified or is None, any
  320. whitespace string is a separator and empty strings are removed
  321. from the result.
  322. """
  323. return []
  324.  
  325. def splitlines(self, keepends=False):
  326. """ 根据换行分割 """
  327. """
  328. S.splitlines(keepends=False) -> list of strings
  329.  
  330. Return a list of the lines in S, breaking at line boundaries.
  331. Line breaks are not included in the resulting list unless keepends
  332. is given and true.
  333. """
  334. return []
  335.  
  336. def startswith(self, prefix, start=None, end=None):
  337. """ 是否起始 """
  338. """
  339. S.startswith(prefix[, start[, end]]) -> bool
  340.  
  341. Return True if S starts with the specified prefix, False otherwise.
  342. With optional start, test S beginning at that position.
  343. With optional end, stop comparing S at that position.
  344. prefix can also be a tuple of strings to try.
  345. """
  346. return False
  347.  
  348. def strip(self, chars=None):
  349. """ 移除两段空白 """
  350. """
  351. S.strip([chars]) -> string or unicode
  352.  
  353. Return a copy of the string S with leading and trailing
  354. whitespace removed.
  355. If chars is given and not None, remove characters in chars instead.
  356. If chars is unicode, S will be converted to unicode before stripping
  357. """
  358. return ""
  359.  
  360. def swapcase(self):
  361. """ 大写变小写，小写变大写 """
  362. """
  363. S.swapcase() -> string
  364.  
  365. Return a copy of the string S with uppercase characters
  366. converted to lowercase and vice versa.
  367. """
  368. return ""
  369.  
  370. def title(self):
  371. """
  372. S.title() -> string
  373.  
  374. Return a titlecased version of S, i.e. words start with uppercase
  375. characters, all remaining cased characters have lowercase.
  376. """
  377. return ""
  378.  
  379. def translate(self, table, deletechars=None):
  380. """
  381. 转换，需要先做一个对应表，最后一个表示删除字符集合
  382. intab = "aeiou"
  383. outtab = ""
  384. trantab = maketrans(intab, outtab)
  385. str = "this is string example....wow!!!"
  386. print str.translate(trantab, 'xm')
  387. """
  388.  
  389. """
  390. S.translate(table [,deletechars]) -> string
  391.  
  392. Return a copy of the string S, where all characters occurring
  393. in the optional argument deletechars are removed, and the
  394. remaining characters have been mapped through the given
  395. translation table, which must be a string of length 256 or None.
  396. If the table argument is None, no translation is applied and
  397. the operation simply removes the characters in deletechars.
  398. """
  399. return ""
  400.  
  401. def upper(self):
  402. """
  403. S.upper() -> string
  404.  
  405. Return a copy of the string S converted to uppercase.
  406. """
  407. return ""
  408.  
  409. def zfill(self, width):
  410. """方法返回指定长度的字符串，原字符串右对齐，前面填充0。"""
  411. """
  412. S.zfill(width) -> string
  413.  
  414. Pad a numeric string S with zeros on the left, to fill a field
  415. of the specified width. The string S is never truncated.
  416. """
  417. return ""
  418.  
  419. def _formatter_field_name_split(self, *args, **kwargs): # real signature unknown
  420. pass
  421.  
  422. def _formatter_parser(self, *args, **kwargs): # real signature unknown
  423. pass
  424.  
  425. def __add__(self, y):
  426. """ x.__add__(y) <==> x+y """
  427. pass
  428.  
  429. def __contains__(self, y):
  430. """ x.__contains__(y) <==> y in x """
  431. pass
  432.  
  433. def __eq__(self, y):
  434. """ x.__eq__(y) <==> x==y """
  435. pass
  436.  
  437. def __format__(self, format_spec):
  438. """
  439. S.__format__(format_spec) -> string
  440.  
  441. Return a formatted version of S as described by format_spec.
  442. """
  443. return ""
  444.  
  445. def __getattribute__(self, name):
  446. """ x.__getattribute__('name') <==> x.name """
  447. pass
  448.  
  449. def __getitem__(self, y):
  450. """ x.__getitem__(y) <==> x[y] """
  451. pass
  452.  
  453. def __getnewargs__(self, *args, **kwargs): # real signature unknown
  454. pass
  455.  
  456. def __getslice__(self, i, j):
  457. """
  458. x.__getslice__(i, j) <==> x[i:j]
  459.  
  460. Use of negative indices is not supported.
  461. """
  462. pass
  463.  
  464. def __ge__(self, y):
  465. """ x.__ge__(y) <==> x>=y """
  466. pass
  467.  
  468. def __gt__(self, y):
  469. """ x.__gt__(y) <==> x>y """
  470. pass
  471.  
  472. def __hash__(self):
  473. """ x.__hash__() <==> hash(x) """
  474. pass
  475.  
  476. def __init__(self, string=''): # known special case of str.__init__
  477. """
  478. str(object='') -> string
  479.  
  480. Return a nice string representation of the object.
  481. If the argument is a string, the return value is the same object.
  482. # (copied from class doc)
  483. """
  484. pass
  485.  
  486. def __len__(self):
  487. """ x.__len__() <==> len(x) """
  488. pass
  489.  
  490. def __le__(self, y):
  491. """ x.__le__(y) <==> x<=y """
  492. pass
  493.  
  494. def __lt__(self, y):
  495. """ x.__lt__(y) <==> x<y """
  496. pass
  497.  
  498. def __mod__(self, y):
  499. """ x.__mod__(y) <==> x%y """
  500. pass
  501.  
  502. def __mul__(self, n):
  503. """ x.__mul__(n) <==> x*n """
  504. pass
  505.  
  506. @staticmethod # known case of __new__
  507. def __new__(S, *more):
  508. """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
  509. pass
  510.  
  511. def __ne__(self, y):
  512. """ x.__ne__(y) <==> x!=y """
  513. pass
  514.  
  515. def __repr__(self):
  516. """ x.__repr__() <==> repr(x) """
  517. pass
  518.  
  519. def __rmod__(self, y):
  520. """ x.__rmod__(y) <==> y%x """
  521. pass
  522.  
  523. def __rmul__(self, n):
  524. """ x.__rmul__(n) <==> n*x """
  525. pass
  526.  
  527. def __sizeof__(self):
  528. """ S.__sizeof__() -> size of S in memory, in bytes """
  529. pass
  530.  
  531. def __str__(self):
  532. """ x.__str__() <==> str(x) """
  533. pass
  534.  
  535. str

str

字符串是 Python 中最常用的数据类型。我们可以使用引号，双引号，或三引号来创建字符串。

  1. a = 'poe'
  2. b = "bruce"
  3. c = """Jacky Chen"""

1：字符串连接

方法一：join方法

  1. a = ['a','b','c','d']
  2. content = ''
  3. content = ' '.join(a)
  4. print(content)

方法二：用字符串的替换占位符替换

  1. a = ['a','b','c','d']
  2. content = ''
  3. content = '%s%s%s%s' % tuple(a)
  4. print(content)

方法三：for循环

  1. a = ['a','b','c','d']
  2. content = ''
  3. for i in a:
  4. content += i
  5. print(content)

注意：方法三效率低，不推荐使用！

原因：在循环连接字符串的时候，他每次连接一次，就要重新开辟空间，然后把字符串连接起来，再放入新的空间，再一次循环，又要开辟新的空间，把字符串连接起来放入新的空间，如此反复，内存操作比较频繁，每次都要计算内存空间，然后开辟内存空间，再释放内存空间，效率非常低，你也许操作比较少的数据的时候看不出来，感觉影响不大，但是你碰到操作数据量比较多的时候，这个方法就要退休了。

2：字符串截取

我们可以通过索引来提取想要获取的字符，可以把python的字符串也做为字符串的列表就更好理解

python的字串列表有2种取值顺序：

1是从左到右索引默认0开始的，最大范围是字符串长度少1

  1. s = 'ilovepython'
  2. s[0]的结果是i

2是从右到左索引默认-1开始的，最大范围是字符串开头

  1. s = 'ilovepython'
  2. s[-1]的结果是n

上面这个是取得一个字符，如果你的实际要取得一段子串的话，可以用到变量[头下标:尾下标]，就可以截取相应的字符串，其中下标是从0开始算起，可以是正数或负数，下标可以为空表示取到头或尾。

比如

  1. s = 'ilovepython'
  2. s[1:5]的结果是love

当使用以冒号分隔的字符串，python返回一个新的对象，结果包含了以这对偏移标识的连续的内容，左边的开始是包含了下边界，比如上面的结果包含了s[1]的值l，而取到的最大范围不包括上边界，就是s[5]的值p

注：s[1:5]形式截头不截尾

3：字符串替换

方法一：使用repalce方法

  1. a = 'hello world'
  2. b = a.replace('world','python')
  3. print(b)

方法二：使用正则表达式

  1. import re
  2. a = 'hello world'
  3. strinfo = re.compile('world')
  4. b = strinfo.sub('python',a)
  5. print(b)

4：字符串比较

cmp方法比较两个对象，并根据结果返回一个整数。cmp(x,y)如果X< Y,返回值是负数 如果X>Y 返回的值为正数。

  1. str1 = 'strch'
  2. str2 = 'strchr'
  3. print(cmp(str1,str2))
  4. ## -1

5：字符串相加

我们通过操作符号+来进行字符串的相加，不过建议还是用其他的方式来进行字符串的拼接，这样效率高点。
原因：在循环连接字符串的时候，他每次连接一次，就要重新开辟空间，然后把字符串连接起来，再放入新的空间，再一次循环，又要开辟新的空间，把字符串连接起来放入新的空间，如此反复，内存操作比较频繁，每次都要计算内存空间，然后开辟内存空间，再释放内存空间，效率非常低。

  1. str1 = 'strch'
  2. str2 = 'strchr'
  3. print(str1+str2)
  4. ## strchstrchr

6：字符串查找

python 字符串查找有4个方法，1 find,2 index方法，3 rfind方法,4 rindex方法。

方法一：find方法

  1. info = 'abca'
  2. print info.find('a')##从下标0开始，查找在字符串里第一个出现的子串，返回结果：0
  3.  
  4. info = 'abca'
  5. print info.find('a',1)##从下标1开始，查找在字符串里第一个出现的子串：返回结果3
  6.  
  7. info = 'abca'
  8. print info.find('')##返回-1,查找不到返回-1

方法二：index方法

python 的index方法是在字符串里查找子串第一次出现的位置，类似字符串的find方法，不过比find方法更好的是，如果查找不到子串，会抛出异常，而不是返回-1

  1. info = 'abca'
  2. print info.index('a')
  3. print info.index('')

7：字符串分割

字符串分割，可以用split,rsplit方法，通过相应的规则来切割成生成列表对象

  1. info = 'name:haha,age:20$name:python,age:30$name:fef,age:55'
  2. content = info.split('$')
  3. print content
  4. ## ['name:haha,age:20', 'name:python,age:30', 'name:fef,age:55']

8：字符串反转

  1. a = 'abcd'
  2. b = a[::-1]##[::-1]通过步进反转
  3. print b

9：字符串编码

10：字符串追加和拼接

通过字符串的占位符来进行字符串的拼接

  1. #1 元组拼接
  2. m = 'python'
  3. astr = 'i love %s' % m
  4. print astr
  5.  
  6. #2 字符串的format方法
  7. m = 'python'
  8. astr = "i love {python}".format(python=m)
  9. print astr
  10.  
  11. #3 字典格式化字符串
  12. m = 'python'
  13. astr = "i love %(python)s " % {'python':m}
  14. print astr

11：字符串复制

  1. #通过变量来进行赋值
  2. fstr = 'strcpy'
  3. sstr = fstr
  4. fstr = 'strcpy2'
  5. print sstr

12：字符串长度

  1. #通过内置方法len()来计算字符串的长度，注意这个计算的是字符的长度。
  2. aa = 'afebb'
  3. bb = '你'
  4. print len(aa)
  5. print len(bb)

13：字符串大小写

  1. #通过下面的upper(),lower()等方法来转换大小写
  2. S.upper()#S中的字母大写
  3. S.lower() #S中的字母小写
  4. S.capitalize() #首字母大写
  5. S.istitle() #S是否是首字母大写的
  6. S.isupper() #S中的字母是否便是大写
  7. S.islower() #S中的字母是否全是小写

14：字符串去空格

  1. #通过strip(),lstrip(),rstrip()方法去除字符串的空格
  2. S.strip() #去掉字符串的左右空格
  3. S.lstrip() #去掉字符串的左边空格
  4. S.rstrip() #去掉字符串的右边空格
  5. #注意：strip()函数不仅可以去空格还可以去除指定的字符，如
  6. S.strip("\n")

15：字符串其他方法

  1. #字符串相关的其他方法:count(),join()方法等。
  2. S.center(width, [fillchar]) #中间对齐
  3. S.count(substr, [start, [end]]) #计算substr在S中出现的次数
  4. S.expandtabs([tabsize]) #把S中的tab字符替换没空格，每个tab替换为tabsize个空格，默认是8个
  5. S.isalnum() #是否全是字母和数字，并至少有一个字符
  6. S.isalpha() #是否全是字母，并至少有一个字符
  7. S.isspace() #是否全是空白字符，并至少有一个字符
  8. S.join()#S中的join，把列表生成一个字符串对象
  9. S.ljust(width,[fillchar]) #输出width个字符，S左对齐，不足部分用fillchar填充，默认的为空格。
  10. S.rjust(width,[fillchar]) #右对齐
  11. S.splitlines([keepends]) #把S按照行分割符分为一个list，keepends是一个bool值，如果为真每行后而会保留行分割符。
  12. S.swapcase() #大小写互换

三：列表 list

  1. class list(object):
  2. """
  3. list() -> new empty list
  4. list(iterable) -> new list initialized from iterable's items
  5. """
  6. def append(self, p_object): # real signature unknown; restored from __doc__
  7. """ L.append(object) -- append object to end """
  8. pass
  9.  
  10. def count(self, value): # real signature unknown; restored from __doc__
  11. """ L.count(value) -> integer -- return number of occurrences of value """
  12. return 0
  13.  
  14. def extend(self, iterable): # real signature unknown; restored from __doc__
  15. """ L.extend(iterable) -- extend list by appending elements from the iterable """
  16. pass
  17.  
  18. def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__
  19. """
  20. L.index(value, [start, [stop]]) -> integer -- return first index of value.
  21. Raises ValueError if the value is not present.
  22. """
  23. return 0
  24.  
  25. def insert(self, index, p_object): # real signature unknown; restored from __doc__
  26. """ L.insert(index, object) -- insert object before index """
  27. pass
  28.  
  29. def pop(self, index=None): # real signature unknown; restored from __doc__
  30. """
  31. L.pop([index]) -> item -- remove and return item at index (default last).
  32. Raises IndexError if list is empty or index is out of range.
  33. """
  34. pass
  35.  
  36. def remove(self, value): # real signature unknown; restored from __doc__
  37. """
  38. L.remove(value) -- remove first occurrence of value.
  39. Raises ValueError if the value is not present.
  40. """
  41. pass
  42.  
  43. def reverse(self): # real signature unknown; restored from __doc__
  44. """ L.reverse() -- reverse *IN PLACE* """
  45. pass
  46.  
  47. def sort(self, cmp=None, key=None, reverse=False): # real signature unknown; restored from __doc__
  48. """
  49. L.sort(cmp=None, key=None, reverse=False) -- stable sort *IN PLACE*;
  50. cmp(x, y) -> -1, 0, 1
  51. """
  52. pass
  53.  
  54. def __add__(self, y): # real signature unknown; restored from __doc__
  55. """ x.__add__(y) <==> x+y """
  56. pass
  57.  
  58. def __contains__(self, y): # real signature unknown; restored from __doc__
  59. """ x.__contains__(y) <==> y in x """
  60. pass
  61.  
  62. def __delitem__(self, y): # real signature unknown; restored from __doc__
  63. """ x.__delitem__(y) <==> del x[y] """
  64. pass
  65.  
  66. def __delslice__(self, i, j): # real signature unknown; restored from __doc__
  67. """
  68. x.__delslice__(i, j) <==> del x[i:j]
  69.  
  70. Use of negative indices is not supported.
  71. """
  72. pass
  73.  
  74. def __eq__(self, y): # real signature unknown; restored from __doc__
  75. """ x.__eq__(y) <==> x==y """
  76. pass
  77.  
  78. def __getattribute__(self, name): # real signature unknown; restored from __doc__
  79. """ x.__getattribute__('name') <==> x.name """
  80. pass
  81.  
  82. def __getitem__(self, y): # real signature unknown; restored from __doc__
  83. """ x.__getitem__(y) <==> x[y] """
  84. pass
  85.  
  86. def __getslice__(self, i, j): # real signature unknown; restored from __doc__
  87. """
  88. x.__getslice__(i, j) <==> x[i:j]
  89.  
  90. Use of negative indices is not supported.
  91. """
  92. pass
  93.  
  94. def __ge__(self, y): # real signature unknown; restored from __doc__
  95. """ x.__ge__(y) <==> x>=y """
  96. pass
  97.  
  98. def __gt__(self, y): # real signature unknown; restored from __doc__
  99. """ x.__gt__(y) <==> x>y """
  100. pass
  101.  
  102. def __iadd__(self, y): # real signature unknown; restored from __doc__
  103. """ x.__iadd__(y) <==> x+=y """
  104. pass
  105.  
  106. def __imul__(self, y): # real signature unknown; restored from __doc__
  107. """ x.__imul__(y) <==> x*=y """
  108. pass
  109.  
  110. def __init__(self, seq=()): # known special case of list.__init__
  111. """
  112. list() -> new empty list
  113. list(iterable) -> new list initialized from iterable's items
  114. # (copied from class doc)
  115. """
  116. pass
  117.  
  118. def __iter__(self): # real signature unknown; restored from __doc__
  119. """ x.__iter__() <==> iter(x) """
  120. pass
  121.  
  122. def __len__(self): # real signature unknown; restored from __doc__
  123. """ x.__len__() <==> len(x) """
  124. pass
  125.  
  126. def __le__(self, y): # real signature unknown; restored from __doc__
  127. """ x.__le__(y) <==> x<=y """
  128. pass
  129.  
  130. def __lt__(self, y): # real signature unknown; restored from __doc__
  131. """ x.__lt__(y) <==> x<y """
  132. pass
  133.  
  134. def __mul__(self, n): # real signature unknown; restored from __doc__
  135. """ x.__mul__(n) <==> x*n """
  136. pass
  137.  
  138. @staticmethod # known case of __new__
  139. def __new__(S, *more): # real signature unknown; restored from __doc__
  140. """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
  141. pass
  142.  
  143. def __ne__(self, y): # real signature unknown; restored from __doc__
  144. """ x.__ne__(y) <==> x!=y """
  145. pass
  146.  
  147. def __repr__(self): # real signature unknown; restored from __doc__
  148. """ x.__repr__() <==> repr(x) """
  149. pass
  150.  
  151. def __reversed__(self): # real signature unknown; restored from __doc__
  152. """ L.__reversed__() -- return a reverse iterator over the list """
  153. pass
  154.  
  155. def __rmul__(self, n): # real signature unknown; restored from __doc__
  156. """ x.__rmul__(n) <==> n*x """
  157. pass
  158.  
  159. def __setitem__(self, i, y): # real signature unknown; restored from __doc__
  160. """ x.__setitem__(i, y) <==> x[i]=y """
  161. pass
  162.  
  163. def __setslice__(self, i, j, y): # real signature unknown; restored from __doc__
  164. """
  165. x.__setslice__(i, j, y) <==> x[i:j]=y
  166.  
  167. Use of negative indices is not supported.
  168. """
  169. pass
  170.  
  171. def __sizeof__(self): # real signature unknown; restored from __doc__
  172. """ L.__sizeof__() -- size of L in memory, in bytes """
  173. pass
  174.  
  175. __hash__ = None
  176.  
  177. list

list

1：创建列表

  1. list1 = ['physics', 'chemistry', 1997, 2000];
  2. list2 = [1, 2, 3, 4, 5 ];
  3. list3 = ["a", "b", "c", "d"];

与字符串的索引一样，列表索引从0开始。列表可以进行截取、组合等

2：访问列表

  1. list1 = ['physics', 'chemistry', 1997, 2000];
  2. list2 = [1, 2, 3, 4, 5, 6, 7 ];
  3. print(list1[0])
  4. print(list2[2:5])#截头不截尾
  5. ## physics
  6. ## [3, 4, 5]

3：append方法：在列表末尾添加新的对象

  1. aList = [123, 'xyz', 'zara', 'abc'];
  2. aList.append( 2009 );
  3. print "Updated List : ", aList;
  4. ## Updated List : [123, 'xyz', 'zara', 'abc', 2009]

4：count方法：统计某个元素在列表中出现的次数

  1. aList = [123, 'xyz', 'zara', 123];
  2. print(aList.count(123))
  3. ## 2

5：extend() 函数用于在列表末尾一次性追加另一个序列中的多个值（用新列表扩展原来的列表）

  1. aList = [123, 'xyz', 'zara', 'abc', 123];
  2. bList = [2009, 'manni'];
  3. aList.extend(bList)
  4.  
  5. print "Extended List : ", aList ;
  6. ## Extended List : [123, 'xyz', 'zara', 'abc', 123, 2009, 'manni']

6：index() 函数用于从列表中找出某个值第一个匹配项的索引位置

  1. aList = [123, 'xyz', 'zara', 'abc'];
  2.  
  3. print "Index for xyz : ", aList.index( 'xyz' ) ;
  4. print "Index for zara : ", aList.index( 'zara' ) ;
  5.  
  6. ##Index for xyz : 1
  7. ## Index for zara : 2

7：insert() 函数用于将指定对象插入列表的指定位置

  1. aList = [123, 'xyz', 'zara', 'abc']
  2.  
  3. aList.insert( 3, 2009)
  4.  
  5. print "Final List : ", aList
  6.  
  7. ## Final List : [123, 'xyz', 'zara', 2009, 'abc']

insert()接收两个参数，list.insert(index, obj)，第一个参数index为要插入的索引位置，第二个参数要插入的元素

8：pop() 函数用于移除列表中的一个元素（默认最后一个元素），并且返回该元素的值

  1. aList = [123, 'xyz', 'zara', 'abc'];
  2.  
  3. print "A List : ", aList.pop();
  4. print "B List : ", aList.pop();
  5.  
  6. ## A List : abc
  7. ## B List : zara

9：remove() 函数用于移除列表中某个值的第一个匹配项

  1. aList = [123, 'xyz', 'zara', 'abc', 'xyz'];
  2.  
  3. aList.remove('xyz');
  4. print "List : ", aList;
  5. aList.remove('abc');
  6. print "List : ", aList;
  7.  
  8. ## List : [123, 'zara', 'abc', 'xyz']
  9. ## List : [123, 'zara', 'xyz']

10：列表的四种遍历方法

  1. aList = [123, 'xyz', 'zara', 123];

方法一：只遍历列表中的值

  1. for value in aList :
  2. print(value)
  3. ####################
  4. 123
  5. xyz
  6. zara
  7. 123

方法二：如果需要遍历列表中的索引与值，就需要用到enumerate

  1. for key,value in enumerate(aList) :
  2. print(key,value)
  3. ######################
  4. (0, 123)
  5. (1, 'xyz')
  6. (2, 'zara')
  7. (3, 123)

enumrate：为可迭代的对象添加序号，默认从0开始！因为列表的索引也是从0开始，所以我们在enumerate中不指定第二个参数，如有需要，可以指定从几开始，如下：

  1. for key,value in enumerate(aList,1) :
  2. print(key,value)
  3. ######################################
  4. (1, 123)
  5. (2, 'xyz')
  6. (3, 'zara')
  7. (4, 123)

方法三：

  1. for i in range(len(aList)) :
  2. print(i,aList[i])
  3. ##############################
  4. (0, 123)
  5. (1, 'xyz')
  6. (2, 'zara')
  7. (3, 123)

range和xrange：指定范围，生成指定的数字

方法四：使用iter()

  1. for i in iter(aList) :
  2. print(i)
  3. ##########################################
  4. 123
  5. xyz
  6. zara
  7. 123

四：元组 tuple

  1. lass tuple(object):
  2. """
  3. tuple() -> empty tuple
  4. tuple(iterable) -> tuple initialized from iterable's items
  5.  
  6. If the argument is a tuple, the return value is the same object.
  7. """
  8. def count(self, value): # real signature unknown; restored from __doc__
  9. """ T.count(value) -> integer -- return number of occurrences of value """
  10. return 0
  11.  
  12. def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__
  13. """
  14. T.index(value, [start, [stop]]) -> integer -- return first index of value.
  15. Raises ValueError if the value is not present.
  16. """
  17. return 0
  18.  
  19. def __add__(self, y): # real signature unknown; restored from __doc__
  20. """ x.__add__(y) <==> x+y """
  21. pass
  22.  
  23. def __contains__(self, y): # real signature unknown; restored from __doc__
  24. """ x.__contains__(y) <==> y in x """
  25. pass
  26.  
  27. def __eq__(self, y): # real signature unknown; restored from __doc__
  28. """ x.__eq__(y) <==> x==y """
  29. pass
  30.  
  31. def __getattribute__(self, name): # real signature unknown; restored from __doc__
  32. """ x.__getattribute__('name') <==> x.name """
  33. pass
  34.  
  35. def __getitem__(self, y): # real signature unknown; restored from __doc__
  36. """ x.__getitem__(y) <==> x[y] """
  37. pass
  38.  
  39. def __getnewargs__(self, *args, **kwargs): # real signature unknown
  40. pass
  41.  
  42. def __getslice__(self, i, j): # real signature unknown; restored from __doc__
  43. """
  44. x.__getslice__(i, j) <==> x[i:j]
  45.  
  46. Use of negative indices is not supported.
  47. """
  48. pass
  49.  
  50. def __ge__(self, y): # real signature unknown; restored from __doc__
  51. """ x.__ge__(y) <==> x>=y """
  52. pass
  53.  
  54. def __gt__(self, y): # real signature unknown; restored from __doc__
  55. """ x.__gt__(y) <==> x>y """
  56. pass
  57.  
  58. def __hash__(self): # real signature unknown; restored from __doc__
  59. """ x.__hash__() <==> hash(x) """
  60. pass
  61.  
  62. def __init__(self, seq=()): # known special case of tuple.__init__
  63. """
  64. tuple() -> empty tuple
  65. tuple(iterable) -> tuple initialized from iterable's items
  66.  
  67. If the argument is a tuple, the return value is the same object.
  68. # (copied from class doc)
  69. """
  70. pass
  71.  
  72. def __iter__(self): # real signature unknown; restored from __doc__
  73. """ x.__iter__() <==> iter(x) """
  74. pass
  75.  
  76. def __len__(self): # real signature unknown; restored from __doc__
  77. """ x.__len__() <==> len(x) """
  78. pass
  79.  
  80. def __le__(self, y): # real signature unknown; restored from __doc__
  81. """ x.__le__(y) <==> x<=y """
  82. pass
  83.  
  84. def __lt__(self, y): # real signature unknown; restored from __doc__
  85. """ x.__lt__(y) <==> x<y """
  86. pass
  87.  
  88. def __mul__(self, n): # real signature unknown; restored from __doc__
  89. """ x.__mul__(n) <==> x*n """
  90. pass
  91.  
  92. @staticmethod # known case of __new__
  93. def __new__(S, *more): # real signature unknown; restored from __doc__
  94. """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
  95. pass
  96.  
  97. def __ne__(self, y): # real signature unknown; restored from __doc__
  98. """ x.__ne__(y) <==> x!=y """
  99. pass
  100.  
  101. def __repr__(self): # real signature unknown; restored from __doc__
  102. """ x.__repr__() <==> repr(x) """
  103. pass
  104.  
  105. def __rmul__(self, n): # real signature unknown; restored from __doc__
  106. """ x.__rmul__(n) <==> n*x """
  107. pass
  108.  
  109. def __sizeof__(self): # real signature unknown; restored from __doc__
  110. """ T.__sizeof__() -- size of T in memory, in bytes """
  111. pass
  112.  
  113. tuple

tuple

Python的元组与列表类似，不同之处在于元组的元素不能修改。元组使用小括号，列表使用方括号。元组创建很简单，只需要在括号中添加元素，并使用逗号隔开即可

tuple只有两个可使用的功能：count , index

1：创建元组

  1. tup1 = ();#创建空元组
  2.  
  3. tup1 = (50,);#元组中只包含一个元素时，需要在元素后面添加逗号

元组与字符串类似，下标索引从0开始，可以进行截取，组合等。元组的访问与列表一样！

2：元组的连接组合

  1. tup1 = (12, 34.56);
  2. tup2 = ('abc', 'xyz');
  3.  
  4. # 以下修改元组元素操作是非法的。
  5. # tup1[0] = 100;
  6.  
  7. # 创建一个新的元组
  8. tup3 = tup1 + tup2;
  9. print tup3;
  10. ##########################################
  11. (12, 34.56, 'abc', 'xyz')

3：删除元组

元组中的元素值是不允许删除的，但我们可以使用del语句来删除整个元组，如下实例:

  1. tup = ('physics', 'chemistry', 1997, 2000);
  2.  
  3. print tup;
  4. del tup;
  5. print "After deleting tup : "
  6. print tup;
  7. ##########################################
  8. 以上实例元组被删除后，输出变量会有异常信息，输出如下所示：
  9. ('physics', 'chemistry', 1997, 2000)
  10. After deleting tup :
  11. Traceback (most recent call last):
  12. File "test.py", line 9, in <module>
  13. print tup;
  14. NameError: name 'tup' is not defined

五：字典 dict

  1. class dict(object):
  2. """
  3. dict() -> new empty dictionary
  4. dict(mapping) -> new dictionary initialized from a mapping object's
  5. (key, value) pairs
  6. dict(iterable) -> new dictionary initialized as if via:
  7. d = {}
  8. for k, v in iterable:
  9. d[k] = v
  10. dict(**kwargs) -> new dictionary initialized with the name=value pairs
  11. in the keyword argument list. For example: dict(one=1, two=2)
  12. """
  13.  
  14. def clear(self): # real signature unknown; restored from __doc__
  15. """ 清除内容 """
  16. """ D.clear() -> None. Remove all items from D. """
  17. pass
  18.  
  19. def copy(self): # real signature unknown; restored from __doc__
  20. """ 浅拷贝 """
  21. """ D.copy() -> a shallow copy of D """
  22. pass
  23.  
  24. @staticmethod # known case
  25. def fromkeys(S, v=None): # real signature unknown; restored from __doc__
  26. """
  27. dict.fromkeys(S[,v]) -> New dict with keys from S and values equal to v.
  28. v defaults to None.
  29. """
  30. pass
  31.  
  32. def get(self, k, d=None): # real signature unknown; restored from __doc__
  33. """ 根据key获取值，d是默认值 """
  34. """ D.get(k[,d]) -> D[k] if k in D, else d. d defaults to None. """
  35. pass
  36.  
  37. def has_key(self, k): # real signature unknown; restored from __doc__
  38. """ 是否有key """
  39. """ D.has_key(k) -> True if D has a key k, else False """
  40. return False
  41.  
  42. def items(self): # real signature unknown; restored from __doc__
  43. """ 所有项的列表形式 """
  44. """ D.items() -> list of D's (key, value) pairs, as 2-tuples """
  45. return []
  46.  
  47. def iteritems(self): # real signature unknown; restored from __doc__
  48. """ 项可迭代 """
  49. """ D.iteritems() -> an iterator over the (key, value) items of D """
  50. pass
  51.  
  52. def iterkeys(self): # real signature unknown; restored from __doc__
  53. """ key可迭代 """
  54. """ D.iterkeys() -> an iterator over the keys of D """
  55. pass
  56.  
  57. def itervalues(self): # real signature unknown; restored from __doc__
  58. """ value可迭代 """
  59. """ D.itervalues() -> an iterator over the values of D """
  60. pass
  61.  
  62. def keys(self): # real signature unknown; restored from __doc__
  63. """ 所有的key列表 """
  64. """ D.keys() -> list of D's keys """
  65. return []
  66.  
  67. def pop(self, k, d=None): # real signature unknown; restored from __doc__
  68. """ 获取并在字典中移除 """
  69. """
  70. D.pop(k[,d]) -> v, remove specified key and return the corresponding value.
  71. If key is not found, d is returned if given, otherwise KeyError is raised
  72. """
  73. pass
  74.  
  75. def popitem(self): # real signature unknown; restored from __doc__
  76. """ 获取并在字典中移除 """
  77. """
  78. D.popitem() -> (k, v), remove and return some (key, value) pair as a
  79. 2-tuple; but raise KeyError if D is empty.
  80. """
  81. pass
  82.  
  83. def setdefault(self, k, d=None): # real signature unknown; restored from __doc__
  84. """ 如果key不存在，则创建，如果存在，则返回已存在的值且不修改 """
  85. """ D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D """
  86. pass
  87.  
  88. def update(self, E=None, **F): # known special case of dict.update
  89. """ 更新
  90. {'name':'alex', 'age': 18000}
  91. [('name','sbsbsb'),]
  92. """
  93. """
  94. D.update([E, ]**F) -> None. Update D from dict/iterable E and F.
  95. If E present and has a .keys() method, does: for k in E: D[k] = E[k]
  96. If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v
  97. In either case, this is followed by: for k in F: D[k] = F[k]
  98. """
  99. pass
  100.  
  101. def values(self): # real signature unknown; restored from __doc__
  102. """ 所有的值 """
  103. """ D.values() -> list of D's values """
  104. return []
  105.  
  106. def viewitems(self): # real signature unknown; restored from __doc__
  107. """ 所有项，只是将内容保存至view对象中 """
  108. """ D.viewitems() -> a set-like object providing a view on D's items """
  109. pass
  110.  
  111. def viewkeys(self): # real signature unknown; restored from __doc__
  112. """ D.viewkeys() -> a set-like object providing a view on D's keys """
  113. pass
  114.  
  115. def viewvalues(self): # real signature unknown; restored from __doc__
  116. """ D.viewvalues() -> an object providing a view on D's values """
  117. pass
  118.  
  119. def __cmp__(self, y): # real signature unknown; restored from __doc__
  120. """ x.__cmp__(y) <==> cmp(x,y) """
  121. pass
  122.  
  123. def __contains__(self, k): # real signature unknown; restored from __doc__
  124. """ D.__contains__(k) -> True if D has a key k, else False """
  125. return False
  126.  
  127. def __delitem__(self, y): # real signature unknown; restored from __doc__
  128. """ x.__delitem__(y) <==> del x[y] """
  129. pass
  130.  
  131. def __eq__(self, y): # real signature unknown; restored from __doc__
  132. """ x.__eq__(y) <==> x==y """
  133. pass
  134.  
  135. def __getattribute__(self, name): # real signature unknown; restored from __doc__
  136. """ x.__getattribute__('name') <==> x.name """
  137. pass
  138.  
  139. def __getitem__(self, y): # real signature unknown; restored from __doc__
  140. """ x.__getitem__(y) <==> x[y] """
  141. pass
  142.  
  143. def __ge__(self, y): # real signature unknown; restored from __doc__
  144. """ x.__ge__(y) <==> x>=y """
  145. pass
  146.  
  147. def __gt__(self, y): # real signature unknown; restored from __doc__
  148. """ x.__gt__(y) <==> x>y """
  149. pass
  150.  
  151. def __init__(self, seq=None, **kwargs): # known special case of dict.__init__
  152. """
  153. dict() -> new empty dictionary
  154. dict(mapping) -> new dictionary initialized from a mapping object's
  155. (key, value) pairs
  156. dict(iterable) -> new dictionary initialized as if via:
  157. d = {}
  158. for k, v in iterable:
  159. d[k] = v
  160. dict(**kwargs) -> new dictionary initialized with the name=value pairs
  161. in the keyword argument list. For example: dict(one=1, two=2)
  162. # (copied from class doc)
  163. """
  164. pass
  165.  
  166. def __iter__(self): # real signature unknown; restored from __doc__
  167. """ x.__iter__() <==> iter(x) """
  168. pass
  169.  
  170. def __len__(self): # real signature unknown; restored from __doc__
  171. """ x.__len__() <==> len(x) """
  172. pass
  173.  
  174. def __le__(self, y): # real signature unknown; restored from __doc__
  175. """ x.__le__(y) <==> x<=y """
  176. pass
  177.  
  178. def __lt__(self, y): # real signature unknown; restored from __doc__
  179. """ x.__lt__(y) <==> x<y """
  180. pass
  181.  
  182. @staticmethod # known case of __new__
  183. def __new__(S, *more): # real signature unknown; restored from __doc__
  184. """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
  185. pass
  186.  
  187. def __ne__(self, y): # real signature unknown; restored from __doc__
  188. """ x.__ne__(y) <==> x!=y """
  189. pass
  190.  
  191. def __repr__(self): # real signature unknown; restored from __doc__
  192. """ x.__repr__() <==> repr(x) """
  193. pass
  194.  
  195. def __setitem__(self, i, y): # real signature unknown; restored from __doc__
  196. """ x.__setitem__(i, y) <==> x[i]=y """
  197. pass
  198.  
  199. def __sizeof__(self): # real signature unknown; restored from __doc__
  200. """ D.__sizeof__() -> size of D in memory, in bytes """
  201. pass
  202.  
  203. __hash__ = None
  204.  
  205. dict

dict

字典是另一种可变容器模型，且可存储任意类型对象。字典的每个键值(key=>value)对用冒号(:)分割，每个对之间用逗号(,)分割，整个字典包括在花括号({})中 ,格式如下所示：

  1. d = {key1 : value1, key2 : value2 }

键必须是唯一的，但值则不必。值可以取任何数据类型，但键必须是不可变的，如字符串，数字或元组。

1：访问字典里的值

  1. dict = {'Name': 'Zara', 'Age': 7, 'Class': 'First'};
  2.  
  3. print "dict['Name']: ", dict['Name'];
  4. print "dict['Age']: ", dict['Age'];
  5. ##########################################
  6. dict['Name']: Zara
  7. dict['Age']: 7

2：修改字典里的值

  1. dict = {'Name': 'Zara', 'Age': 7, 'Class': 'First'};
  2.  
  3. dict['Age'] = 8; # update existing entry
  4. dict['School'] = "DPS School"; # Add new entry
  5.  
  6. print "dict['Age']: ", dict['Age'];
  7. print "dict['School']: ", dict['School'];
  8. ##########################################
  9. dict['Age']: 8
  10. dict['School']: DPS School

3：删除操作

能删单一的元素也能清空字典，清空只需一项操作。显示删除一个字典用del命令，如下实例：

  1. dict = {'Name': 'Zara', 'Age': 7, 'Class': 'First'};
  2.  
  3. del dict['Name']; # 删除键是'Name'的条目
  4. dict.clear(); # 清空词典所有条目
  5. del dict ; # 删除词典
  6.  
  7. print "dict['Age']: ", dict['Age'];
  8. print "dict['School']: ", dict['School'];
  9. ##########################################
  10. dict['Age']:
  11. Traceback (most recent call last):
  12. File "test.py", line 8, in <module>
  13. print "dict['Age']: ", dict['Age'];
  14. TypeError: 'type' object is unsubscriptable

clear() 函数用于删除字典内所有元素：

  1. dict = {'Name': 'Zara', 'Age': 7};
  2.  
  3. print "Start Len : %d" % len(dict)
  4. dict.clear()
  5. print "End Len : %d" % len(dict)

注：clear函数是删除字典里的所有元素，删除后，该字典仍然存在，不过是个空字典而已

4： copy() 函数返回一个字典的浅复制

  1. dict1 = {'Name': 'Zara', 'Age': 7};
  2.  
  3. dict2 = dict1.copy()
  4. print "New Dictinary : %s" % str(dict2)
  5. ##########################################
  6. New Dictinary : {'Age': 7, 'Name': 'Zara'}

有关深浅复制的区别，请点击这里！

5：fromkeys() 函数用于创建一个新字典，以序列seq中元素做字典的键，value为字典所有键对应的初始值

  1. seq = ('name','age','sex')
  2. dic = dict.fromkeys(seq)
  3. print(dic)
  4. #########################################
  5. {'age': None, 'name': None, 'sex': None}

可以指定一个值，如：

  1. seq = ('name','age','sex')
  2. dic = dict.fromkeys(seq,10)
  3. print(dic)
  4. ##########################################
  5. {'age': 10, 'name': 10, 'sex': 10}

6：get() 函数返回指定键的值，如果值不在字典中返回默认值

  1. dic = {'Name': 'Zara', 'Age': 27}
  2. print(dic.get('Age'))
  3. print(dic.get('Sex','Never'))#Never为设置的默认值
  4. ##########################################
  5. 27
  6. Never

7：has_key() 函数用于判断键是否存在于字典中，如果键在字典dict里返回true，否则返回false

  1. dic = {'Name': 'Zara', 'Age': 27}
  2. print(dic.has_key('Name'))
  3. print(dic.has_key('Sex'))
  4. ##########################################
  5. True
  6. False

8：items() 函数以列表返回可遍历的(键, 值) 元组数组

  1. dic = {'Name': 'Zara', 'Age': 27}
  2. print(dic.items())
  3. ##########################################
  4. [('Age', 27), ('Name', 'Zara')]

9：keys() 函数以列表返回一个字典所有的键

  1. dic = {'Name': 'Zara', 'Age': 27}
  2. print(dic.keys())
  3. ##########################################
  4. ['Age', 'Name']

10：values() 函数以列表返回字典中的所有值

  1. dic = {'Name': 'Zara', 'Age': 27}
  2. print(dic.values())
  3. ##########################################
  4. [27, 'Zara']

11：update() 函数把字典dict2的键/值对更新到dict1里

  1. dict1 = {'Name': 'Zara', 'Age': 7}
  2. dict2 = {'Sex': 'female' }
  3. dict1.update(dict2)
  4. print(dict1)
  5. ##########################################
  6. {'Age': 7, 'Name': 'Zara', 'Sex': 'female'}

12：字典的遍历

方法一：

  1. dict1 = {'Age': 7, 'Name': 'Zara', 'Sex': 'female'}
  2. for k,v in dict1.items() :
  3. print(k,v)
  4. ##########################################
  5. ('Age', 7)
  6. ('Name', 'Zara')
  7. ('Sex', 'female')

方法二：

  1. dict1 = {'Age': 7, 'Name': 'Zara', 'Sex': 'female'}
  2. for (k,v) in dict1.items() :
  3. print(k,v)
  4. ##########################################
  5. ('Age', 7)
  6. ('Name', 'Zara')
  7. ('Sex', 'female')

 

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