内置函数

Posted 2020-10-29 人无远虑

 abs

 取绝对值

 all

print(all([1,-3,3]))#有不为0的就是真

1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
2 True
3 
4 Process finished with exit code 0

执行结果

 any

print(any([1,-3,0])) #有一个为真就为真

1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
2 True
3 
4 Process finished with exit code 0

执行结果

 ASCII

print(ascii([1,-3,\'大大勾拳\'])) #把内存的数据对象变成一个可打印的字符串

1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
2 [1, -3, \'\\u5927\\u5927\\u52fe\\u62f3\']
3 
4 Process finished with exit code 0

执行结果

 bin

print(bin(255)) #把数字从十进制转二进制

1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
2 0b11111111
3 
4 Process finished with exit code 0

执行结果

 bool

print(bool([]))#判断真假，有数据就是真，没有数据就是假

1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
2 False
3 
4 Process finished with exit code 0

执行结果

 bytearry

b=bytearray(\'abcde\',encoding=\'utf-8\')#字节数组  可修改的二进制
print(b[1])
b[1]=50             #把二进制变成数组的格式，并且可以进行修改
print(b)

1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
2 98
3 bytearray(b\'a2cde\')
4 
5 Process finished with exit code 0

执行结果

 callable

def as1():pass
print(callable([])) #判断是否可以被调用

1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
2 False
3 
4 Process finished with exit code 0

执行结果

  chr

print(chr(97))  #数字对应的asc码，参数必须是数字

1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
2 a
3 
4 Process finished with exit code 0

执行结果

 ord

print(ord(\'d\'))#asc码对应的数字，参数必须是字符

1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
2 100
3 
4 Process finished with exit code 0

执行结果

 complie

code =\'for i in range(10):print(i)\'         #把一段字符串变成可以编译的代码
c=compile(code,\'\',\'exec\')                   
exec(c)                                     #直接exec()就可以，跟eval一样用，更简单

 1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
 2 0
 3 1
 4 2
 5 3
 6 4
 7 5
 8 6
 9 7
10 8
11 9
12 
13 Process finished with exit code 0

执行结果

 exec

把一段字符串变成可以编译的代码

code =\'for i in range(10):print(i)\'         #把一段字符串变成可以编译的代码
exec(code)       

 1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
 2 0
 3 1
 4 2
 5 3
 6 4
 7 5
 8 6
 9 7
10 8
11 9
12 
13 Process finished with exit code 0

执行结果

 eval

code =\'1+2*3\'         #把一段字符串变成可以编译的代码,针对整数加减乘除

 print(eval(code))

1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
2 7
3 
4 Process finished with exit code 0

执行结果

 divmod

print(divmod(5,1))   #返回商跟余数

1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
2 (5, 0)
3 
4 Process finished with exit code 0

执行结果

 lambda

 匿名函数

def sayhi(n):
    print(n)

sayhi(5)

cal=lambda  n :print(n)             #lambda 就是匿名函数，只能处理简单的
cal(5)

#或者简单的三元运算
cal= lambda n:3 if n<4 else n
print(cal(2))
#需要配合filter使用，filter是过滤出自己想要的
#也可配合map使用

1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
2 5
3 5
4 3
5 
6 Process finished with exit code 0

执行结果

 filter

 过滤自己想要的数据，配合lambda使用

res=filter(lambda n:n>5,range(10))
for i in res:
    print(i)

1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
2 6
3 7
4 8
5 9
6 
7 Process finished with exit code 0

执行结果

 map

把传入的每个值进行处理，再返回一个列表

res=map(lambda  n:n*n,range(10))        ###filter是吧过滤出来的合格的打印出来，map是把传入的每一个值进行处理，再返回一个列表
for i in res:                                                       
    print(i)

 1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
 2 0
 3 1
 4 4
 5 9
 6 16
 7 25
 8 36
 9 49
10 64
11 81
12 
13 Process finished with exit code 0

执行结果

 reduce

import  functools
res=functools.reduce(lambda x,y:x+y,range(10))  #累加，把传入的值，进行处理，然后将结果累加起来
print(res)

1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
2 45
3 
4 Process finished with exit code 0

执行结果

 frozenset

冻结不可变的集合

a= frozenset([1,4,33,212,33,35])  #set是有添加，清楚功能的，forozenset 没有这些功能了

globals

print(globals())        #返回的是当前整个程序里所以的key，valve格式，变量名是key，对应的变量是valve

1 C:\\Users\\Administrator\\PycharmProjects\\untitled3\\venv\\Scripts\\python.exe C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py
2 {\'__name__\': \'__main__\', \'__doc__\': None, \'__package__\': None, \'__loader__\': <_frozen_importlib_external.SourceFileLoader object at 0x0045C490>, \'__spec__\': None, \'__annotations__\': {}, \'__builtins__\': <module \'builtins\' (built-in)>, \'__file__\': \'C:/Users/Administrator/PycharmProjects/2018-2-27/测试.py\', \'__cached__\': None}
3 
4 Process finished with exit code 0

执行结果

 hash

 中文叫散列 通关一系列算法，把无序的数据转换成有映射关系的有序数据，就是哈希

 hex

 把一个数字转成16进制

 id

 返回内存地址

 iter

 迭代器

 max

 返回最大值

 next

 跟迭代器的__next__方法一样

 oct

 转八进制

print(oct(8))#oct 转八进制

1 C:\\Users\\qiangql\\AppData\\Local\\Programs\\Python\\Python36-32\\python.exe C:/Users/qiangql/PycharmProjects/untitled/内置函数测.py
2 0o10
3 
4 Process finished with exit code 0

执行结果

 pow

print(pow(2,8)) #多少次方

1 C:\\Users\\qiangql\\AppData\\Local\\Programs\\Python\\Python36-32\\python.exe C:/Users/qiangql/PycharmProjects/untitled/内置函数测.py
2 256
3 
4 Process finished with exit code 0

执行方法

 range

 循环

 repr

 用字符串表示对象

 reversed

 反转，类似列表的用法

 round

print(round(1.3342,3))  #保留小数点后几位，参数可以调

1 C:\\Users\\qiangql\\AppData\\Local\\Programs\\Python\\Python36-32\\python.exe C:/Users/qiangql/PycharmProjects/untitled/内置函数测.py
2 1.334
3 
4 Process finished with exit code 0

执行结果

 slice

d=range(10) 
d=list(d)
print(d[slice(2,5)]) #切片

1 C:\\Users\\qiangql\\AppData\\Local\\Programs\\Python\\Python36-32\\python.exe C:/Users/qiangql/PycharmProjects/untitled/内置函数测.py
2 [2, 3, 4]
3 
4 Process finished with exit code 0

执行结果

 sorted

 把字典排序

a={1:3,2:11,99:3,-2:13}
print(sorted(a))  #默认key
print(sorted(a.items())) 
print(sorted(a.items(),key=lambda x:x[1])) #a按照valve排序，valve不能有字符串

1 C:\\Users\\qiangql\\AppData\\Local\\Programs\\Python\\Python36-32\\python.exe C:/Users/qiangql/PycharmProjects/untitled/内置函数测.py
2 [-2, 1, 2, 99]
3 [(-2, 13), (1, 3), (2, 11), (99, 3)]
4 [(1, 3), (99, 3), (2, 11), (-2, 13)]
5 
6 Process finished with exit code 0

执行结果

 sum

 求和

 vars

 返回一个对象的所有属性名，没啥用

 zip

 拉链的意思，组合两个列表，以元组的形式显示。

a=[1,2,3,4,5]                   #如果a，b数量不一样，按照最少的来
b=[\'a\',\'b\',\'c\',\'d\',\'e\']

for i in zip(a,b):
    print(i)
print(type(i))

1 C:\\Users\\qiangql\\AppData\\Local\\Programs\\Python\\Python36-32\\python.exe C:/Users/qiangql/PycharmProjects/untitled/内置函数测.py
2 (1, \'a\')
3 (2, \'b\')
4 (3, \'c\')
5 (4, \'d\')
6 (5, \'e\')
7 <class \'tuple\'>

执行结果

 __import__

 调用一个程序文件，有用，例如

1 C:\\Users\\qiangql\\AppData\\Local\\Programs\\Python\\Python36-32\\python.exe C:/Users/qiangql/PycharmProjects/untitled/内置函数测.py
2 welcome to index page
3 username:qiangql
4 password1234
5 user has passed authentication
6 welcome to home page
7 waibu

执行结果

直接调用了111的内容。

 

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