如何在python中將所有負數更改為零？ (How do I change all negative numbers to zero in python?)

問題描述

如何在python中將所有負數更改為零？ (How do I change all negative numbers to zero in python?)

我有一個列表

    list1 = [‑10,1,2,3,9,‑1]

我想把負數改為零，這樣它看起來像

    list1 = [0,1,2,3,9,0]

我該怎麼做？謝謝！

參考解法

方法 1:

You can use comprehensions:

list2 = [0 if i < 0 else i for i in list1]

or

list2 = [(i > 0) * i for i in list1]

Note that the second variant only works with Python 3 since True == 1 and False == 0. It should work with Python 2 but there is no guarantee.

方法 2:

You can alternatively use the map function

map(lambda x: max(x,0),list1)

方法 3:

Iterate through the list and if it's less that 0 change it

def do_the_thing(old_list):
    new_list = []
    for num in old_list:
        if num < 0:
             new_list.append(0)
        else:
            new_list.append(num)
    return new_list

方法 4:

Another option is to is numpy like this:

list2 = numpy.array(list1)
list2 = list2 * (list2 >= 0)

(by hassISC、Selcuk、Thiru、timlyo、yoavsnake)

參考文件

1. How do I change all negative numbers to zero in python? (CC BY‑SA 2.5/3.0/4.0)