python dict常用方法简介

#!/user/bin/env pthon# -*- coding: UTF-8 -*-# Created by: PyCharm.# Author:     qinjie# Date:       2017/12/12# Time:       20:48d1 = {}  # 构造一个空字典d2 = {'spam': 2, 'eggs': 3}  # 构造2个key-value的元素的字典d3 = {'food': {'eggs': 3, 'bread': 4}}  # 构造一个嵌套的字典d4 = dict.fromkeys(['a', 'b'])  # 其他构造方法,只构造key => {'a': None, 'b': None}d5 = dict(zip(['a', 'b'], [1, 2]))  # 其他构造方法,key value => {'a': 1, 'b': 2}d6 = dict(a=1, b=2)  # 字典构造 => {'b': 2, 'a': 1}print(d2['eggs'])           # 获取元素key值是否在字典里面       => 3print(d3['food']['eggs'])   # 获取嵌套列表中的key值            => 3print('eggs' in d2)         # 判断key值‘eggs’是否在字典中      => Trueprint(d2.keys())            # 获取字典的所有key值视图              => dict_keys(['spam', 'eggs'])print(d2.values())          # 获取字典中所有的value值           => dict_values([2, 3])print(d2.items())           # 获取item对象                    => dict_items([('spam', 2), ('eggs', 3)])print(d2.copy())            # cpoy d2                       => {'spam': 2, 'eggs': 3}print(d2.get('food','hh'))  # 获取'food'key值,如不存在使用'hh' => hhd1.update(d2)               # d1与d2字典合并print(d1)                   # =》{'eggs': 3, 'spam': 2}d1.pop('eggs')              # 删除d1中的eggs值print(d1)                   # =》{'spam': 2}print(len(d1))              # => 获取d1的长度d1['t'] = 1                 # => 如果有对应的key则变修改、如果没有对应的key值则新增该元素del d1['t']                 # => 根据key删除对应的值print(list(d2.keys()))      # => 根据字典的key值生成列表           ['eggs', 'spam']print(list(d2.values()))    # => 根据字典里面的value进行生成列表    [3, 2]print(list(d2.items()))     # => 根据字典里的k v 来生成列表        [('eggs', 3), ('spam', 2)]  实际嵌套了两个元组print(d1.keys() & d2.keys())# => 两个字典的key做与 意味同时存在两个字典中的keyd7 = {x: x*2 for x in range(10)}print(d7)                   # => {0: 0, 1: 2, 2: 4, 3: 6, 4: 8, 5: 10, 6: 12, 7: 14, 8: 16, 9: 18}d8 = dict(zip([1,2],['a','b']))# 等价于d9 = {k:v for(k,v) in zip([1,2],['a','b'])}print('d8',d8)print('d9',d9)