15个python小例子助你快速回忆python

# -*- coding: utf-8 -*-
"""
====================================
@File Name ：20个小知识.py
@Time ： 2023/1/17 17:59
@Program IDE ：PyCharm
@Create by Author ： 一一吴XX
@Motto："The trick, William Potter, is not minding that it hurts."
====================================
"""
import random
import re
from iteration_utilities import deepflatten
"""
1.字符串的翻转
"""
Str = "Hello World"
print(Str[::-1])   # dlroW olleH

"""
2.单词大小写
"""
Str = "i love python"
print(Str.title())   # I Love Python 单词首字母大写
print(Str.upper())   # I LOVE PYTHON   所有字母大写
print(Str.capitalize()) # I love python 字符串首字母大写


"""
3.字符串拆分
"""
Str1 = "I love Python"
Str2 = "I/love/Python"
Str3 = "   I love Python   "

print(Str.split())  # ['i', 'love', 'python'] 空格进行拆分，返回的是列表
print(Str2.split('/'))    # ['I', 'love', 'Python']
print(Str3.strip())  #I love Python  默认去除字符串的2边空格
print(type(Str3.strip()))  #<class 'str'>  输出类型

"""
4.列表中的字符串合并
"""
list1 = ["I","love","Python"]
print(' '.join(list1))   # I love Python

"""
5.去除字符串中不需要的字符
"""
Str = "I/ love. python"
print(' '.join(re.split('\W+',Str)) ) # \W 表示除英文字母以外的

"""
6.寻找字符串中唯一的元素
"""
Str = "wwweeerfttttg"
print(''.join(set(Str)))   #grfwte

list1 = [2,5,6,5,5,6,2]
print(list(set(list1)))  #[2, 5, 6]

"""
7.将元素进行重复
"""
Str = "python"
print(Str * 2)   # pythonpython
list1 = [1,2,3]
print(list1 * 2)  # [1, 2, 3, 1, 2, 3]

'''或者用 + 处理'''
Str1 = ""
list12 = []
for i in range(2):
   Str1 += Str
   list12.extend(list1)

print(Str1)
print(list12)

"""
8.基于列表的扩展
"""
list13 = [2,2,2,2]
print([2 * x for x in list13])   # [4, 4, 4, 4]

list14 = [[1,2,3],[4,5,6],[7,8,9]]
print([i for k in list14 for i in k])  #    [1, 2, 3, 4, 5, 6, 7, 8, 9] 等同于 php的 array_reduce($a,'array_merge',[])

list15 = [[1,2,3],[4,5,6],[7,8,9]]
print(list(deepflatten(list15)))  #[1, 2, 3, 4, 5, 6, 7, 8, 9]   不知道嵌套深度使用


list16 = [[1,2,3],[4,5,6],[7,[8,9]]]
print(list(deepflatten(list15)))   #[1, 2, 3, 4, 5, 6, 7, 8, 9]

"""
9.统计列表中元素的频率
"""
from collections import Counter
list17 = [1,1,1,2,3,3,4,5,6,6]
count = Counter(list17)
print(count)   # Counter({1: 3, 3: 2, 6: 2, 2: 1, 4: 1, 5: 1})
print(count[1])  # 得到1出现的频率是 3

#手动实现
dict1 = {}
for i in list17:
   if i in dict1:
      dict1[i] += 1
   else:
      dict1[i] = 1

print(max(dict1,key = lambda x:dict1[x]))


"""
10 判断字符串所含元素是否相同
"""
Str1,Str2,Str3 = "qwet","qwet","tewq"
if Counter(Str1) == Counter(Str2) and Counter(Str2) == Counter(Str3):
   print("元素相同")
else:
   print("元素不相同")

"""
11 将数字字符串转化为数字列表
"""

Str = "123456789"
print([int(i) for i in Str])  #[1, 2, 3, 4, 5, 6, 7, 8, 9]
#或者
print(list(map(int,Str)))

"""
12 使用try-except-finally模块
"""
a = 1
b = 4
try:
   a.append(b)
except AttributeError as e:
   print(e)
else:
   print(a)
finally:
   print("执行完毕")

"""
13 使用enumerate() 函数来获取索引-数值对
"""
Str = "python"
for i in enumerate(Str):
   print(i)

"""
输出
(0, 'p')
(1, 'y')
(2, 't')
(3, 'h')
(4, 'o')
(5, 'n')

"""
C1 = [1,2,3,4,5]
for i in enumerate(C1):
   print(i)

"""
输出
(0, 1)
(1, 2)
(2, 3)
(3, 4)
(4, 5)
"""

"""
13 字典的合并
"""
a = {
   "a":1,
   "b":2
}
b = {
   "c":3,
   "d":4
}

#方法1
combine = {** a,** b}
print(combine)   #{'a': 1, 'b': 2, 'c': 3, 'd': 4}
#方法2
a.update(b)
print(a)   # {'a': 1, 'b': 2, 'c': 3, 'd': 4}

"""
14 随机采样
"""
a = "jdkosjodifjs"
b = [1,2,3,4,5,6]
print(random.sample(a,3))  #['d', 'f', 'j']
print(random.sample(b,3))  #[1, 3, 5]

"""
15 检查唯一性
"""
a = [1,2,3,4,4]
if len(list(set(a))) == len(a):
   print("元素唯一")
else:
   print("元素不唯一")