python字典

dic = {}
# 增
# 1.普通方法  (推荐)
dic["top"] = "369"
dic["middle"] = "左手"
dic["bottom"] = "杰克爱"
print(dic)  #  {'top': '369', 'middle': '左手', 'bottom': '杰克爱'}
# 改造
dic = {}
dic["top"] = []
dic["middle"] = []
dic["bottom"] = []
dic["top"].append("the boy")
print(dic) # {'top': ['the boy'], 'middle': [], 'bottom': []}

# 删
dic = {'top': '369', 'middle': '左手', 'bottom': '杰克爱'}
#pop()       通过键去删除键值对 (若没有该键可设置默认值,预防报错)
res = dic.pop("middle")
print(res)  # 左手
print(dic) # {'top': '369', 'bottom': '杰克爱'}
# 可以给pop设置第二个参数值,以防止键不存在时报错
res = dic.pop("middle1234","该键不存在")
print(res)  # 该键不存在

#popitem()   删除最后一个键值对
dic = {'top': '369', 'middle': '左手', 'bottom': '杰克爱'}
res = dic.popitem()
print(res)  # ('bottom', '杰克爱')
print(dic)  # {'top': '369', 'middle': '左手'}

#clear()  清空字典
dic.clear()
print(dic) # {}

# 改
#update() 批量更新(有该键就更新,没该键就添加)

# 推荐使用
# 没该键就添加
dic_new = {"jungle":"karsa","support":"宝蓝"}
dic = {'top': '369', 'middle': '左手', 'bottom': '杰克爱'}
dic.update(dic_new)
print(dic)
# {'top': '369', 'middle': '左手', 'bottom': '杰克爱', 'jungle': 'karsa', 'support': '宝蓝'}

# 有该键就更新
dic_new = {"top":"the bug","support":"xboyww","xiaozhang":"王思聪"}
dic.update(dic_new)
print(dic)
#{'top': 'the bug', 'middle': '左手', 'bottom': '杰克爱', 'jungle': 'karsa', 'support': 'xboyww', 'xiaozhang': '王思聪'}

# (了解)
dic.update(ww="李文",zl="张强")
print(dic)
# {'top': 'the bug', 'middle': '左手', 'bottom': '杰克爱', 'jungle': 'karsa', 'support': 'xboyww', 'xiaozhang': '王思聪', 'ww': '李文', 'zl': '张强'}

# 查
# get()    通过键获取值(若没有该键可设置默认值,预防报错)
dic = {"top":"the bug","support":"xboyww","xiaozhang":"王思聪"}
# res = dic["top123"] # error
# get 在获取字典键时,如果不存在,不会发生任何报错,返回的是None
# res = dic.get("top123") # None
# 可以在获取不到该键时,给与默认值提示.
res = dic.get("top123","抱歉,该键不存在")
print(res) # 抱歉,该键不存在
# 其他操作
#keys()   将字典的键组成新的可迭代对象
dic = {"top":"the bug","support":"xboyww","xiaozhang":"王思聪"}
res = dic.keys()
print(res , type(res))
# dict_keys(['top', 'support', 'xiaozhang']) <class 'dict_keys'>

#values() 将字典中的值组成新的可迭代对象 ***
res = dic.values()
print(res , type(res))
# dict_values(['the bug', 'xboyww', '王思聪']) <class 'dict_values'>

#items()  将字典的键值对凑成一个个元组,组成新的可迭代对象 ***
res = dic.items()
print(res , type(res))
# dict_items([('top', 'the bug'), ('support', 'xboyww'), ('xiaozhang', '王思聪')]) <class 'dict_items'>

# for i in res:
#     print(i)
'''
('top', 'the bug')
('support', 'xboyww')
('xiaozhang', '王思聪')
'''
for k,v in res:
    print(k,v)
'''
top the bug
support xboyww
xiaozhang 王思聪
'''