python之常用内置函数

>>> dir("__builtins__")
[‘__add__‘, ‘__class__‘, ‘__contains__‘, ‘__delattr__‘, ‘__dir__‘, ‘__doc__‘, ‘,_eq__‘, ‘__format__‘, ‘__ge__‘, ‘__getattribute__‘, ‘__getitem__‘, ‘__getnewarg,__‘, ‘__gt__‘, ‘__hash__‘, ‘__init__‘, ‘__iter__‘, ‘__le__‘, ‘__len__‘, ‘__lt__, ‘__mod__‘, ‘__mul__‘, ‘__ne__‘, ‘__new__‘, ‘__reduce__‘, ‘__reduce_ex__‘, ‘__epr__‘, ‘__rmod__‘, ‘__rmul__‘, ‘__setattr__‘, ‘__sizeof__‘, ‘__str__‘, ‘__subcasshook__‘, ‘capitalize‘, ‘casefold‘, ‘center‘, ‘count‘, ‘encode‘, ‘endswith‘,expandtabs‘, ‘find‘, ‘format‘, ‘format_map‘, ‘index‘, ‘isalnum‘, ‘isalpha‘, ‘isecimal‘, ‘isdigit‘, ‘isidentifier‘, ‘islower‘, ‘isnumeric‘, ‘isprintable‘, ‘issace‘, ‘istitle‘, ‘isupper‘, ‘join‘, ‘ljust‘, ‘lower‘, ‘lstrip‘, ‘maketrans‘, ‘prtition‘, ‘replace‘, ‘rfind‘, ‘rindex‘, ‘rjust‘, ‘rpartition‘, ‘rsplit‘, ‘rstri‘, ‘split‘, ‘splitlines‘, ‘startswith‘, ‘strip‘, ‘swapcase‘, ‘title‘, ‘translat‘, ‘upper‘, ‘zfill‘]

abs(-1) #取绝对值或者复数的模
max([1,2,3])、min([1,2,3]) #最大最小值
len(‘abc‘)、len([1,2,3])、len((1,2,3))#序列长度
divmod(5,2)//(2,1)#内置函数，把...转换成复数，如complex(‘2‘)返回(2+0j),compl
ex(‘2+3j‘)返回(2+3j)
pow()# 内置函数，乘方。如果有第三个参数，则表示乘方的结果对第三个参数取余，如w(2,3)
返回8，pow(2,3,4)返回0
round(1)//1.0#浮点数　　

callable("变量") #函数是否可调用。注意：变量要定义过
isinstance(x,[11,22,33])#判断X是不是有列表或者整型等，如果是，返回True,不是返回False
cmp(‘hello‘,‘hello‘)#比较
(x)range([start,] stop[, step])# 快速生成序列

long(x)
float(x) #把。。转换成浮点数
complex(x) //复数
str(x)#转换成字符串
list(x)#转换成字符串
tuple(x) //元组

进制件的相互转换
 r = hex(10)#十六进制
 r = oct(10)#八进制
 r= bin(10)#二进制
 r= int(10)#十进制
 i= int("11",base=10)#进制间的相互转换base后跟 2/8/10/16
 print(i)

chr(x)//返回x对应的字符，如chr(65)返回‘A‘
ord(x)//返回字符对应的ASC码数字编号，如ord(‘A‘)返回65
#最常用的例子就是生随机验证码
import random
temp = ""
for i in range(4):
    num = random.randrange(0,4)
    if num == 3 or num == 1:
        li = random.randrange(0,10)
        temp = temp + str(li)
    else:
        rad = random.randrange(65,91)
        c = chr(rad)
        temp += c
print(temp)

len()：序列长度
max()：序列中最大值
min()：最小值
reduce()：归并

filter()：过滤序列，具体用法如下
def f1(x):
    # if x > 22:
    #     return True
    # else:
    #     return False
    return x >22
# ret = filter(f1,[11,22,33,44])
ret = filter(lambda x: x > 22, [11,22,33,44])
for i in ret:
    print(i)
map()：并行遍历，可接受一个function类型的参数，同filter()函数

zip()：并行遍历，用法具体如下
f1 = ["a","b","c"]
f2 = [11,22,33]
set = zip(f1,f2)
for i in set:
    print(i)