Python_day4

	Python	PHP
functional programming	Allows to pass a function itself as a parameter to another function, and also allows to return a function
Higher order functions	abs(), the call to the function is not the function itself As a function itself, the function name is actually a variable that can change the pointer, but this is generally not done . The function name can be assigned to the variable so that the variable also points to the function variable = abs Higher-order functions: functions that can take functions as arguments x = -5 y = 6 f = abs print(add(x,y,f))	$a = "abs"; function test($a){            echo $a(-2); } test($a);
map()	Apply a function to an iterable object map(function,Iterable) def f(x):     return x*x l = [1, 2, 3, 4, 5, 6, 7, 8, 9] res = map(f,l) print(list(res))
reduce()	Starting from the first two, into the function, the return value of the execution and the third number continue to be passed in until the execution is complete reduce(function,Iterable) from functools import reduce def p(x,y):     return x*y l = [1,2,3] print(reduce(p,l)) the end result is a number If the Iterable has only one number, return the value directly