[数据结构与算法]50 个有趣的 Python 一行代码，都很实用

▍1、字母异位词

两个单词如果包含相同的字母，次序不同，则称为字母易位词(anagram)。

例如，“silent”和“listen”是字母易位词，而“apple”和“aplee”不是易位词。

from collections import Counter
s1 = 'below'
s2 = 'elbow'
print('anagram') if Counter(s1) == Counter(s2) else print('not an anagram')

使用一行Python代码，就能判断出来了。

▍2、二进制转十进制

decimal = int('1010', 2)
print(decimal) #10

▍3、将字符串转换为小写

print("Hi my name is XiaoF".lower())
# 'hi my name is xiaof'
print("Hi my name is XiaoF".casefold())
# 'hi my name is xiaof'

▍4、将字符串转换为大写

print("hi my name is XiaoF".upper())
# 'HI MY NAME IS XIAOF'

▍5、将字符串转换为字节

print("convert string to bytes using encode method".encode())
# b'convert string to bytes using encode method'

▍6、拷贝文件

import shutil

shutil.copyfile('source.txt', 'dest.txt')

▍7、快速排序

qsort = lambda l: l if len(l) <= 1 else qsort([x for x in l[1:] if x < l[0]]) + [l[0]] + qsort([x for x in l[1:] if x >= l[0]])
print(qsort([17, 29, 11, 97, 103, 5]))
# [5, 11, 17, 29, 97, 103]

▍8、n个连续数的和

n = 10
print(sum(range(0, n+1)))
# 55

▍9、交换两个变量的值

a,b = b,a

▍10、斐波纳契数列

fib = lambda x: x if x<=1 else fib(x-1) + fib(x-2)
print(fib(20))
# 6765

▍11、将嵌套列表合并为一个列表

main_list = [[0, 1, 2], [11, 12, 13], [52, 53, 54]]
result = [item for sublist in main_list for item in sublist]
print(result)
#[0, 1, 2, 11, 12, 13, 52, 53, 54]

▍12、运行一个HTTP服务器

python3 -m http.server 8000
python2 -m SimpleHTTPServer

▍13、反转列表

numbers = [0, 1, 2, 11, 12, 13, 52, 53, 54]
print(numbers[::-1])
# [54, 53, 52, 13, 12, 11, 2, 1, 0]

▍14、阶乘

import math
fact_5 = math.factorial(5)
print(fact_5)
# 120

▍15、在列表推导式中使用for和if

even_list = [number for number in [1, 2, 3, 4] if number % 2 == 0]
print(even_list)
# [2, 4]

▍16、列表中最长的字符串

words = ['This', 'is', 'a', 'list', 'of', 'words']
result = max(words, key=len)
print(result)
# 'words'

▍17、列表推导式

li = [num for num in range(0, 10)]
print(li)
# [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

▍18、集合推导式

num_set = {num for num in range(0, 10)}
print(num_set)
# {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}

▍19、字典推导式

dict_numbers = {x: x*x for x in range(1, 5)}
print(dict_numbers)
# {1: 1, 2: 4, 3: 9, 4: 16}

▍20、if-else

print("even") if 4 % 2==0 else print("odd")

▍21、无限循环

while 1:0

▍22、检查数据类型

print(isinstance(2, int))
# True
print(isinstance("allwin", str))
# True
print(isinstance([3, 4, 1997], list))
# True

▍23、While循环

a = 5
while a > 0:
? ? a = a - 1
print(a)
# 0

▍24、使用print语句写入文件

print("Hello, World!", file=open('file.txt', 'w'))

既可打印出信息，还能将信息保存文件。

▍25、计算一个字符在字符串中出现的频率

print("umbrella".count('l'))
# 2

▍26、合并列表

list1 = [1, 2, 4]
list2 = ['XiaoF']
list1.extend(list2)
print(list1)
# [1, 2, 4, 'XiaoF']

▍27、合并字典

dict1 = {'name': 'weiwei', 'age': 23}
dict2 = {'city': 'Beijing'}
dict1.update(dict2)
print(dict1)
# {'name': 'weiwei', 'age': 23, 'city': 'Beijing'}

▍28、合并集合

set1 = {0, 1, 2}
set2 = {11, 12, 13}
set1.update(set2)
print(set1)
# {0, 1, 2, 11, 12, 13}

▍29、时间戳

import time
print(time.time())

▍30、列表中出现次数最多的元素

test_list = [9, 4, 5, 4, 4, 5, 9, 5, 4]
most_frequent_element = max(set(test_list), key=test_list.count)
print(most_frequent_element)
# 4

▍31、嵌套列表

numbers = [[num] for num in range(10)]
print(numbers)
# [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9]]

▍32、八进制转十进制

print(int('30', 8))?
# 24

▍33、将键值对转换为字典

result = dict(name='XiaoF', age=23)
print(result)
# {'name': 'XiaoF', 'age': 23}

▍34、求商和余数

quotient, remainder = divmod(4, 5)

print(quotient, remainder)
# 0 4

divmod()函数返回当参数1除以参数2时，包含商和余数的元组。

▍35、删除列表中的重复项

print(list(set([4, 4, 5, 5, 6])))
# [4, 5, 6]

▍36、按升序排序列表

print(sorted([5, 2, 9, 1]))
# [1, 2, 5, 9]

▍37、按降序排序列表

print(sorted([5, 2, 9, 1], reverse=True))
# [9, 5, 2, 1]

▍38、获取小写字母表

import string
print(string.ascii_lowercase)
# abcdefghijklmnopqrstuvwxyz

▍39、获取大写字母表

import string
print(string.ascii_uppercase)
# ABCDEFGHIJKLMNOPQRSTUVWXYZ

▍40、获取0到9字符串

import string
print(string.digits)
# 0123456789

▍41、十六进制转十进制

print(int('da9', 16))
# 3497

▍42、日期时间

import time
print(time.ctime())
# Thu Aug 13 20:00:00 2021

▍43、将列表中的字符串转换为整数

print(list(map(int, ['1', '2', '3'])))
# [1, 2, 3]

▍44、用键对字典进行排序

d = {'one': 1, 'four': 4, 'eight': 8}
result = {key: d[key] for key in sorted(d.keys())}
print(result)
# {'eight': 8, 'four': 4, 'one': 1}

▍45、用键值对字典进行排序

x = {1: 2, 3: 4, 4: 3, 2: 1, 0: 0}
result = {k: v for k, v in sorted(x.items(), key=lambda item: item[1])}
print(result)
# {0: 0, 2: 1, 1: 2, 4: 3, 3: 4}

▍46、列表旋转

li = [1, 2, 3, 4, 5]
# li[n:] + li[:n], 右变左
print(li[2:] + li[:2])
# [3, 4, 5, 1, 2]
# li[-n:] + li[:-n], 左变右
print(li[-1:] + li[:-1])
# [5, 1, 2, 3, 4]

▍47、将字符串中的数字移除

message = ''.join(list(filter(lambda x: x.isalpha(), 'abc123def4fg56vcg2')))
print(message)
# abcdeffgvcg

▍48、矩阵变换

old_list = [[1, 2, 3], [3, 4, 6], [5, 6, 7]]
result = list(list(x) for x in zip(*old_list))
print(result)
# [[1, 3, 5], [2, 4, 6], [3, 6, 7]]

▍49、列表过滤

result = list(filter(lambda x: x % 2 == 0, [1, 2, 3, 4, 5, 6]))
print(result)
# [2, 4, 6]

▍50、解包

a, *b, c = [1, 2, 3, 4, 5]

print(a) # 1
print(b) # [2, 3, 4]
print(c) # 5