python之内置函数

#取绝对值 
>>> abs(-123)
12

#取最小值
min(22,12,888)
12

#取最大值
max(22,12,888)
888

#取长度
len("string")
6
len([1,2,3,4,5,6])
6

#获取商和余
>>> divmod(10,3)
(3, 1)

#取值的几次方
>>> pow(2,3)
8

#四舍五入
>>> round(1.5,0)
2.0 　　

#求和
>>> li = [1,2,3,4]
>>> sum(li)
10

#type() 查看数据类型 
>>> sum(li)
10
>>> type(li)
<class ‘list‘>

#int() int转换为整数类型
>>> a = ‘123‘
>>> type(a)
<class ‘str‘>
>>> b = int(a)
>>> type(b)
<class ‘int‘>

#str() 将整数转为字符串
>>> a = ‘123‘
>>> type(a)
<class ‘str‘>
>>> b = int(a)
>>> type(b)
<class ‘int‘>
>>> c = str(b)
>>> type(c)
<class ‘str‘>

#list() 将字符串转为列表
>>> s = str("123")
>>> type(s)
<class ‘str‘>
>>> l = list(s)
>>> print(l)
[‘1‘, ‘2‘, ‘3‘]
>>> type(l)
<class ‘list‘>

#tuple()将数据类型转为元组
>>> li = [‘a‘,‘b‘,‘c‘]
>>> tu = tuple(li)
>>> type(tu)
<class ‘tuple‘>
>>> print(tu)
(‘a‘, ‘b‘, ‘c‘)

#hex() 将整数转换为16进制的字符串类型
>>> num = 14
>>> he = hex(num)
>>> print(he)
0xe
>>> type(he)
<class ‘str‘>

#oct()   将一个整数转换为一个八进制字符串
>>> num = 14
>>> oc = oct(num)
>>> print(oc)
0o16
>>> type(oc)
<class ‘str‘>

#bin()　　 将一个整数转换为一个二进制的字符串
>>> num = 5
>>> b = bin(num)
>>> print(b)
0b101
>>> type(b)
<class ‘str‘>

#chr()   将一个整数转换为一个字符
>>> st = chr(65)
>>> print(st)
A

#ord()   将一个字符转换为它的整数值
>>> num = ord(‘A‘)
>>> print(num)
65

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#随机验证码生成

import random

temp = ""
for i in range(6):
    num = random.randrange(0,4)
    if num ==3  or num == 1:
        rad2 = random.randrange(0,10)
        temp = temp + str(rad2)
    else:
        rad1 = random.randrange(65,91)
        c1 = chr(rad1)
        temp = temp + c1
print(temp)

#filter 过滤满足条件的元素
>>> a = [ 1,2,3,4]
>>> b = filter(lambda x: x > 2, a)
>>> for i in b:
...     print(i)
...
3
4

#zip
name = [‘a‘,‘b‘]
age = [11,22]
result = zip(name,age)
for i in result:
    print(i) 

#执行结果
(‘a‘, 11)
(‘b‘, 22)

#map
>>> def test(x):
...     return x - 50
...
>>> num = [150, 200, 25]
>>> map(test,num)
<map object at 0x0000000000D5AEB8>
>>> for i in map(test,num):
...     print(i)
...
100
150
-25

#reversed
>>> a = [1,2,3]
>>> ret = reversed(a)
>>> for i in ret:
...     print(i)
...
3
2
1

#enumerate

a = [‘a‘,‘b‘,‘c‘]
dic = {}
for k,i in enumerate(a,10):
    print(k,i)
    dic[k] = i
print(dic)

#all() 循环参数 ，如果每个元素都为真那么all的返回值都为真
def all(iterable):
    for i in iterable:
        if not i:
            return False
    return True
li = [0,1,2,0]
result = all(li)
print(result)

#只要有一个值为真则为真

li = [1,2,0]
print(any(li))

#ID查看内存地址
>>> a = "test"
>>> id(a)
14265624

#查看全局变量
>>> a = "test"
>>> print(globals())
{‘a‘: ‘test‘, ‘__doc__‘: None, ‘__spec__‘: None, ‘__loader__‘: <class ‘_frozen_i
mportlib.BuiltinImporter‘>, ‘__name__‘: ‘__main__‘, ‘__package__‘: None, ‘__buil
tins__‘: <module ‘builtins‘ (built-in)>}

#locals()

>>> def test():
...     a = "hehe"
...     print(locals())
...
>>> test()
{‘a‘: ‘hehe‘}

#查看对象是否可调用
>>> a = "123"
>>> callable(a)
False
>>> callable(len)
True

#dir()　　　　返回当前范围内的变量、方法和定义的类型列表

>>> dir(list)
[‘__add__‘, ‘__class__‘, ‘__contains__‘, ‘__delattr__‘, ‘__delitem__‘, ‘__dir__‘
, ‘__doc__‘, ‘__eq__‘, ‘__format__‘, ‘__ge__‘, ‘__getattribute__‘, ‘__getitem__‘
, ‘__gt__‘, ‘__hash__‘, ‘__iadd__‘, ‘__imul__‘, ‘__init__‘, ‘__iter__‘, ‘__le__‘
, ‘__len__‘, ‘__lt__‘, ‘__mul__‘, ‘__ne__‘, ‘__new__‘, ‘__reduce__‘, ‘__reduce_e
x__‘, ‘__repr__‘, ‘__reversed__‘, ‘__rmul__‘, ‘__setattr__‘, ‘__setitem__‘, ‘__s
izeof__‘, ‘__str__‘, ‘__subclasshook__‘, ‘append‘, ‘clear‘, ‘copy‘, ‘count‘, ‘ex
tend‘, ‘index‘, ‘insert‘, ‘pop‘, ‘remove‘, ‘reverse‘, ‘sort‘]

#eval
>>> a = 1
>>> eval("a+1")
2

#input
>>> print(input("内容:"))
内容:a
a

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#isinstance()
#写函数，判断用户传入的对象（字符串、列表、元组）长度是否大于5
def length(p):
    if isinstance(p,str) or isinstance(p,list) or isinstance(p,tuple):
        if len(p) >5:
            return "长度大于5"
        else:
            return False
    return None
temp = [1,2,3]
ret = length(temp)
print(ret)

# ###################### 普通函数 ######################
# 定义函数（普通方式）
def func(arg):
    return arg + 1
    
# 执行函数
result = func(123)
    
# ###################### lambda ######################
    
# 定义函数（lambda表达式）
my_lambda = lambda arg : arg + 1
    
# 执行函数
result = my_lambda(123)

ret = filter(lambda x : x > 22, [11,22,33,44])
for i in ret:
    print(i)