Lambda, map, reduce, filter in Python

filter (function, sequence): Executes function (item) on item in sequence, and the item that executes the result of true is composed of a list/string/ Tuple (depending on the type of sequence).

Filter (function or None, sequence), list, tuple, or string: entry is function and list/tuple/string, return value is Item List/tuple/string.

map (function, sequence) : Executes function (item) on item in sequence, and the execution result function (item) is made into a list to return.

Map (function, sequence[, sequence, ...]), List: The entry parameter is for the function and list/tuple/string, and the return value is a function (item).

reduce (function, sequence, starting_value): Invokes function for the item order in sequence, and can be called as an initial value if there is a starting_value. function can receive only 2 parameters, the first value in sequence and the second worth argument to function, and then the return value of function and the third worth parameter to function, and then return only one result.

Reduce (function, sequence[, initial]), value: The entry is a function and a list/tuple/string and an initial value, and the return value is numeric.

#Coding=utf-8" "Created on 2016-12-14@author:jennifer Project: Usage of filter, map, reduce, lambda in Python" "#1.LAMBDA usage, before the colon is the argument, after the colon is the expression, the return value, the simplest functionPrint[(LambdaX:X*X) (x) forXinchRange (11)]#results: [0, 1, 4, 9, (+) , +/-, +, +, Bayi, +]Print(LambdaX:X*X) (3)#Results: 9g=Lambdax:x*xPrintG (4)#Results:#2.filter Usage: Returns the argument that the execution result is true (the entry parameter is a list word OFDM group)PrintFilterLambdaX:x*x-4,range (10))#results: [0, 1, 3, 4, 5, 6, 7, 8, 9]#3.map Usage: Executes the function sequentially on the list entry parameter. The entry is a list of how many lists there should be. PrintMapLambdaX:x*x-4,range (10))#results: [ -4, -3, 0, 5, A, (+), +,--)PrintMapLambdaX,y:x*y-4,range (3), [8,9,10])#results: [ -4, 5, +]#4.reduce usage: First pass the first value in sequence and the second worth parameter to function, then pass the function return value and the third worth parameter to Fuction, and finally return a result value#the number of incoming parameters can only be 2PrintReduceLambdaX,y:x*y-4,range (4))#results: -40#calculates 0 to 100 of the andPrintReduceLambdaX,y:x+y, Range (101))#Results: 5050PrintReduceLambdaX,y:x+y, Range (101), 100)#results: 5150

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Lambda, map, reduce, filter in Python