python中强大的for用法

Posted 2020-12-13 Hello world !

#!/usr/local/bin/python3

# -*- coding: UTF-8 -*-

##1.遍历

#遍历字符串

s = \'I love you\'

    for i in s:

        print(i)

print(\'\\n\')

#遍历列表

l = [\'y\', \'l\', \'b\']

    for i in l:

　　print(i)

print(\'\\n\')

#通过enumerate获得下标和val

for i, v in enumerate(l):

    print(i, v)

print(\'\\n\')

#遍历字典：

d = {\'a\': \'apple\', "b": "blanan", "c": "car"}

#以下三种写法输出一样

for i in d:

    print(i, d.get(i))

for k, v in d.items():

    print(k, v)

for k, v in dict.items(d):

    print(k, v)

print(\'\\n\')

##2.列表生成

print(range(10))

print(range(0, 10))

for i in range(10):

    print(i)

print(\'\\n\')

#强制转换为列表

print(list(range(1, 11)))

print([i for i in range(1, 11)])

print([i * 3 for i in range(1, 11)])

print([str(i) for i in range(1, 11)])

print([i for i in range(1, 11) if i % 2 == 0])

print(\'\\n\')

#实现冒泡排序

l = [1, 12, 4, 2, 0, 8, 3, 7]

n = len(l)

for i in range(n - 1):

    for j in range(i + 1, n):

        if l[i] > l[j]:

            l[i], l[j] = l[j], l[i]

print(l)

 

输出：

 

#初始化一个5行4列的二维列表

line = 5

column = 4

dp = [[0] * (column) for _ in range(line)]

print(dp)