Python之每个人都应该知道的30个一行代码程序

① 转置矩阵
old_list = [[1, 2, 3], [3, 4, 6], [5, 6, 7]]
list(list(x) for x in zip(*old_list))
[[1, 3, 5], [2, 4, 6], [3, 6, 7]]

② 二进制转十进制
decimal = int('1010', 2)
print(decimal) #10
10

③ 字符串大写转小写
# 方法一 lower()
"Hi my name is Allwin".lower()
# 'hi my name is allwin'
# 方法二 casefold()
"Hi my name is Allwin".casefold()
# 'hi my name is allwin'
'hi my name is allwin'

④ 字符串小写转大写
"hi my name is Allwin".upper()
# 'HI MY NAME IS ALLWIN'
'HI MY NAME IS ALLWIN'

⑤ 将字符串转换为字节
"convert string to bytes using encode method".encode()
# b'convert string to bytes using encode method'
b'convert string to bytes using encode method'

⑥ 复制文件内容
import shutil; shutil.copyfile('source.txt', 'dest.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]])
qsort([1,3,2])
[1, 2, 3]

⑧ n 个连续数之和
n = 3
sum(range(0, n+1))
6

⑨ 交换两个变量
a=1
b=2
a,b = b,a

⑩ 斐波那契数列
fib = lambda x: x if x<=1 else fib(x-1) + fib(x-2)
fib(10)
55

⑪ 将嵌套列表合并为一个列表
main_list = [[1,2],[3,4],[5,6,7]]
[item for sublist in main_list for item in sublist]
[1, 2, 3, 4, 5, 6, 7]

⑫ 运行 HTTP 服务器
python3 -m http.server 8000

⑬ 反转列表
numbers = 'I Love China'
numbers[::-1]
'anihC evoL I'

⑭ 返回阶乘
import math; fact_5 = math.factorial(5)
fact_5
120

⑮ 判断列表推导式
even_list = [number for number in [1, 2, 3, 4] if number % 2 == 0]
even_list
[2, 4]

⑯ 取最长字符串
words = ['This', 'is', 'a', 'list', 'of', 'words']
max(words, key=len)
'words'

⑰ 列表推导式
li = [num for num in range(0,100)]
# this will create a list of numbers from 0 to 99

⑱ 集合推导式
num_set = { num for num in range(0,100)}
# this will create a set of numbers from 0 to 99

⑲ 字典推导式
dict_numbers = {x:x*x for x in range(1,5) }
# {1: 1, 2: 4, 3: 9, 4: 16}

⑳ if-else
print("even") if 4%2==0 else print("odd")
even

㉑ 无限循环
while 1:0

㉒ 检查数据类型
isinstance(2, int)
isinstance("allwin", str)
isinstance([3,4,1997], list)

㉓ while 循环
a=5
while a > 0: a = a - 1; print(a)

㉔ 使用 print 语句写入到文件里
print("Hello, World!", file=open('source.txt', 'w'))

㉕ 统计字频
print("umbrella".count('l'))

㉖ 合并两个列表
list1.extend(list2)
# contents of list 2 will be added to the list1

㉗ 合并两个字典
dict1.update(dict2)
# contents of dictionary 2 will be added to the dictionary 1

㉘ 合并两个集合
set1.update(set2)
# contents of set2 will be copied to the set1

㉙ 时间戳
import time; print(time.time())
1632146103.8406303

㉚ 统计最多的元素
test_list = [9, 4, 5, 4, 4, 5, 9, 5, 4]
most_frequent_element = max(set(test_list), key=test_list.count)
most_frequent_element