Python 高阶函数 传入参数是函数

环境信息

• ModelArts
  • Notebook - pytorch1.4-cuda10.1-cudnn7-ubuntu18.04
    • JupyterLab - Notebook - Conda-python3

高阶函数 传入参数是函数

自定义函数

def add(num1,num2,fun):
    return fun(num1)+fun(num2)

add(-1,1,abs)

2

add

<function __main__.add(num1, num2, fun)>

abs

<function abs(x, /)>

map 映射

my_list = [1,3,5,7]
# my_list不变，用fun去处理iterables的每一个元素，并返回一个新的map对象
result = map(lambda x:x*x,my_list)
list(result)

reduce 累计

from functools import reduce
my_list = [1,3,5,7]
# reduce简介: fun(fun(fun(x1,x2),x3),x4)
result = reduce(lambda x,y:x*10+y,my_list)
result

1357

help

help(abs)

Help on built-in function abs in module builtins:

abs(x, /)
    Return the absolute value of the argument.

help(map)

Help on class map in module builtins:

class map(object)
 |  map(func, *iterables) --> map object
 |  
 |  Make an iterator that computes the function using arguments from
 |  each of the iterables.  Stops when the shortest iterable is exhausted.
 |  
 |  Methods defined here:

......

help(reduce)

Help on built-in function reduce in module _functools:

reduce(...)
    reduce(function, sequence[, initial]) -> value
    
    Apply a function of two arguments cumulatively to the items of a sequence,
    from left to right, so as to reduce the sequence to a single value.
    For example, reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) calculates
    ((((1+2)+3)+4)+5).  If initial is present, it is placed before the items
    of the sequence in the calculation, and serves as a default when the
    sequence is empty.

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