Python Study to 4 basics

Basic built-in functions

Supplemental built-in functions:

1, callable () #判断 (function) can be executed or called, this function returns a value of Ture or False def F1 (): Pass print (callable (F1)) 2, Chr () #把数字转换成ASCII字符 Print (Chr (65)) 3, Ord () #把ASCII字符串转换成对应的数字 Print (Ord (",")) 4, Randrange () #需要导入 import random module, this function produces a random number I=import ran D.range (3,5) Print (i) 5, compile (s, "<string>", "exec") #把一个字符串编译成python代码 m= "Liang Waijun" s= "Print (m)" R = Compil E (S, "<string>", "exec") print (R) Exec (r) 6, eval () converts a string into a Python expression, and Python executes an expression to get the return value s= "8*8" R=eval (s) print (R) 7, EXEC () #执行python code or string, exec () has no return value 8, dir () #快速查看一个对象提供了那些功能 print (dir (dict)) 9, Help () #帮忙查找一个对象的操作源码 Help (DIC T) 10, filter (function, iterated object) #筛选, matches the condition has return value, does not meet the condition of no return value Def f2 (a): If a > 22:return True li = [11,22,33,44,55] # fi Lter Inner Loop second parameter # result = [] # for item in second parameter: # r = First parameter (item) # if r: # result () # RET     Urn Result # filter ret = filter (F2,li) #循环第二个参数, let each loop element execute a function, if the function returns a value of true, represents a legitimate element. Print (ret) lambda notation: li = [11,22,33,44,55]ret = Filter (lambda a:a >, li) Print (list (ret)) 11, Map (function, iterated object (data type for loop)) Li = [one, one, one, one, one] def F2 (a): Return a + 100result = map (F2, Li) Print (list result) uses the representation of a lambda expression: result = Map (lambda a:a + $, li) prin T (list result) Note: The essential difference between filter and map filter: The function returns true to add the element to the result Map: Add the function return value to the result 12, globals () #定义所有的全局变量13, Locals ( ) #定义所有的局部变量14, Hash () #转换成哈希值, commonly used for dictionary keys to save s = "gang" Print (Hash (s)) 15, Len () #测试字符串长度 # python 3 default by character () s = "Li Jie" Print (len (s)) # byte length, python2.7 default by byte s = "Li Jie" b = bytes (s, encoding= "Utf-8") print (len (b)) 16, sum () #求和函数 s = [11,22,33,44 ] Print (sum (s)) 17, pow () #求某个数的多少次方S = POW (2,10) print (s) 18, slince () #切片函数 s = "sssssssss" Print (S[0:2:2]) 19, s Orted () #对有序数据类型进行排序 (including: list, tuple, string) Li = (11,22,33,1,5,8,) s =sorted (LI) print (S,type (s)) 20, round () #四舍五入Round (1.4) 21,     Zip () #把相同数据类型的相同位置的元素组成一个元素 L1 = ["Alex", one, one, all,] L2 = ["is", one, 11, and] L3 = ["NB",, 22, 33,] r = Zip (L1, L2, L3) #Print (list (r)) temp = list (r) [0] ret = "". Join (temp) print (ret) 

　　

Python Study to 4 basics