python3的字典使用技巧

info = {'101': 'Luola','102': 'Maliya', '103':'Alex'}

方式一：
for key in info:
    print(key,info[key])
print (30*'$')

方式二：
for k,v in info.items():
    print(k,v)

输出字典的项
for d in info.items():
    print(d)
print (30*'$')
输出key
for a in info.keys():
    print(a)
print (30*'$')
输出value
for b in info.values():
    print(b)

#字典增加

dict1 = {'name': 'Rose', 'age': 30, 'sex': '女'}

dict1['id'] = 1010

print(dict1)

# 结果 {'name': 'Lisa', 'age': 30, 'sex': '女', 'id': 1010}

#字典删除

del

l1 = [ 1, 2, 3 ]
l2 = [ 'x', 'y', 'z']
l3 = [ 'x', 'y' ]
print(dict(zip(l1,l3)))
{1: 'x', 2: 'y'}
 

kk=input()

nickey={'a': ['apple', 'abandon', 'ant'], 'b': ['banana', 'bee', 'become'], 'c': ['cat', 'come'], 'd': 'down'}

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for aa in nickey.keys():

    if aa==kk:

        for mm in nickey[aa]:

            print(mm,end=" ")

.Python的字典可以用来计数，让要被计数的元素作为key值，它出现的频次作为value值，只要在遇到key值后更新它对应的value即可。现输入一个单词，使用字典统计单词中各个字母出现频次。

x = {}
y = input()
for i in y:
    x[i] = y.count(i)
print(x)

import operator
dic_instance = {3: 1, 2: 23, 1: 17}
sort_key_dic_instance = dict(sorted(dic_instance.items(), key=operator.itemgetter(0)))  #按照key值升序
sort_val_dic_instance = dict(sorted(dic_instance.items(), key=operator.itemgetter(1)))  #按照value值升序
print(sort_key_dic_instance)  # output:{1: 17, 2: 23, 3: 1}
print(sort_val_dic_instance)  # output:{3: 1, 1: 17, 2: 23}