如何在功能上编写此表达式? [英] How to write this expression functionally?

问题描述

我想在功能上重写以下python代码:

I want to rewrite the following python code functionally:

lst = [0.0] * 10
for pos in [2,5]:
    lst[pos] = 1.0

这是我的尝试，但不正确:

This is my attempt, but is incorrect:

lst = (lambda zeros:
          map(
              lambda pos: zeros[pos] = 1.0, [2,5])
      )([0.0] * 10)

我得到的错误是 lambda无法包含赋值.

使用列表理解，解决方案是:

Using list comprehension, the solution is:

lst = [ 1.0 if x in [2,5] else 0.0 for x in range(10) ]

推荐答案

在您自己的答案中，我确实更喜欢列表理解，但是如果我要在功能上进行一些尝试，我想我会使用 lambda 函数和 map :

I do prefer the list comprehension in your own answer, but if I were to do it with more of a functional touch, I think I would use a lambda function and a map:

lazy = map(lambda element: 1 if element in [2,5] else 0, range(10))

请注意， map 是Python 3中的一个惰性迭代器.如果要获得评估的 list ，则必须将该行括在显式的 list(..中..)构造函数:

Note that map is a lazy iterator in Python 3. If you want an evaluated list you have to enclose the line in an explicit list(...) constructor:

lst = list(map(lambda element: 1 if element in [2,5] else 0, range(10)))

这篇关于如何在功能上编写此表达式?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！