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')
//代码效果参考：http://www.ezhiqi.com/bx/art_6837.html
'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
//代码效果参考：http://www.ezhiqi.com/zx/art_1898.html
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)]
//代码效果参考：http://www.ezhiqi.com/zx/art_1588.html
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'))
2
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
