【python】python进阶技巧

a = [5, 7, 2, 4, 3]
index = list(range(len(a)))
index.sort(key=lambda i: a[i])  # 从大到小只需要添加 负号就行 (key=lambda i: -a[i])

print("从小到大对应的索引：", index)
从小到大对应的索引： [2, 4, 3, 0, 1]   

a = "123"

print(a)
123

a = '"123"'

print(a)
"123"

a = {"jack": 20, "jerry": 19, "babo": 24}
b = {value: key for key, value in a.items()}

print(b)
{20: 'jack', 19: 'jerry', 24: 'babo'}

from collections import Counter

a = [1, 1, 1, 2, 2, 3, 4, 5]

print(Counter(a))
Counter({1: 3, 2: 2, 3: 1, 4: 1, 5: 1})

from collections import Counter

a = "fasdfasdfwqgsdgjh"
print(Counter(a))
Counter({'f': 3, 's': 3, 'd': 3, 'a': 2, 'g': 2, 'w': 1, 'q': 1, 'j': 1, 'h': 1

a = "a,b,c"
b = a.split(",")
print(b)
['a', 'b', 'c']

a = ['a', 'b', 'c']
b = ''.join(a)
print(b)
abc