常用模块——math,random,os

1. math模块

   '''
   math模块：数学模块    方便一些数据计算
   '''
   import math
   print(math.pi)
   r = 12.89636
   print(math.ceil(r))  # 13  向上取整
   print(math.floor(r))  # 12  向下取整
   print(math.factorial(4))  # 阶乘  4*3*2*1---> 24
   print(math.pow(4, 3))  # pow(m,n) 表示的是m的n次方
   print(math.fabs(-19.65))  # 绝对值
   print(math.sqrt(10))  # 10开平方
   print(abs(-19.65))
   # builtins.py  模块默认加载
   # print(),max(),list(),str(),id(),type()
   # import builtins
              

2. random模块

   '''
    random模块:
       print(random.random())  # 生成 [0,1)的随机浮点数
       print(random.uniform(20, 30))  # 生成[20,30]的随机浮点数
       print(random.randint(10, 30))  # 生成[10,30]的随机整数
       print(random.randrange(20, 30))  # 生成[20,30)的随机整数
       print(random.choice('abcdefg'))  # 从列表里随机取出一个元素
       print(random.sample('abcdefghij', 3)) # 从列表里随机取出指定个数的元素
   '''
   import random
   
   # 获取[0,1)之间的小数
   ran = random.random()
   print(ran)
   code = ''
   s = 'qwertyuiopasdfghjklzxcvbnm1234567890QWERTYUIOPASDFGHJKLZXCVBNM'
   for i in range(4):
       ran = random.choice(s)
       print(ran)
       code += ran
   print(code)
   names = ['aaa', 'bbb', 'ccc', 'ddd']
   # name = random.choice(names)
   # print('表演节目的是:',name)
   name = random.sample(names, 2)  # 指定个数的随机获取元素
   print('表演节目的是:', name)
   r = random.randrange(1, 20)  # 给定范围回去随机数randrange(start,stop,step=1)
   print(r)
   # random.randint(1,20)
   r = random.uniform(1, 20)
   print(r)
              

3. os模块

   '''
     os:开发中会涉及文件和路径的操作
     mkdir（‘文件夹名字|路径’）
     getcwd()  获取当前路径
     rmdir()  也可以删除文件夹，只能删除空的文件夹
     remove()  删除文件
     import shutil
     shutil.rmtree()  ----> 删除有内容文件夹
   '''
   import os
   
   # os.mkdir('files')  # 如果文件夹已经存在则报错FileExistsError:  当文件已存在时，无法创建该文件。: 'files'
   print(os.getcwd())  # 获取当前文件所在的位置（路径） C:\Users\running\PycharmProjects\day12_模块
   os.chdir('files')
   print(os.getcwd()) 
   # print(a)
   # result = os.remove('files')
   # print(result)
   # # os.mkdir(r'c:\foo\files')
   # result =os.remove(r'c:\foo\files\a1.py')
   # print(result)
   # 推荐删除文件夹
   # import shutil
   # shutil.rmtree('files')
   
   # 案例
   import os
   
   # os.rmdir('files')
   # 是否是文件夹
   r = os.path.isdir(r'c:\foo\a1.txt')
   print(r)
   # 是否是文件判断
   r = os.path.isfile(r'c:\foo\a1.txt')
   print(r)
   # 获取目录下的所有的子文件
   file_list = os.listdir(r'c:\foo')
   print(file_list)
   for i in file_list:
       # os.path.join(path1,path2..)  拼接路径
       path = os.path.join(r'c:\foo', i)
       print(path)
       r = os.path.isfile(path)
       print("isfile:", r)
       r = os.path.isdir(path)
       print("isdir:", r)
   # 删除一个文件夹中所有文件
   files = os.listdir(r'c:\foo\files')
   # 遍历删除
   for file in files:
       path = os.path.join(r'c:\foo\files', file)
       if os.path.isfile(path):
           os.remove(path)
   print('删除完毕')
   
   '''
   os模块: 其他方法
   '''
   import os
   # os.chdir(r'c:\foo\files')
   # open('a1.txt','w')
   # print(os.environ)
   # print(os.environ.get('OS'))
   # print(os.environ.get('PATH'))
   # path = os.path.abspath('a1.txt')  # absolute path
   # print(path)
   # # os.remove(path)
   # result = os.path.split(r'C:\Users\running\PycharmProjects\day12_模块\a1.txt')
   # print(result)
   # result = os.path.dirname(r'C:\\Users\\running\\PycharmProjects\\day12_模块')
   # print(result)
   # abspath = os.path.abspath(__file__)
   # print(abspath)  # C:\Users\running\PycharmProjects\day12_模块\模块os_6.py
   # path = os.path.dirname(os.path.dirname(abspath))
   # print(path)
   # result = os.path.split(r'C:\Users\running\PycharmProjects\day12_模块')
   # print(result)
   # result = os.path.splitext(r'C:\Users\running\PycharmProjects\day12_模块\a1.html')
   # print(result)
   # result =os.path.splitext('https://www.baidu.com/img/dong_1388792da98c99c5b52f9e39557c31ca.gif')
   # print(result[1])