Python：如何将for循环的结果合并到一个输出中？

Question

numbers = [1, 2, 3]

for number in numbers:
   number = number * 2 

#For the output I will get:
2
4
6

如何在不使用print语句的情况下修改我的代码以便结果（例如[2,4,6]）？

Answer 1

使用列表理解：

[num*2 for num in numbers]

>>> numbers = [1, 2, 3]
>>> [num*2 for num in numbers]
[2, 4, 6]
>>> 

Answer 2

创建新的列表类型变量result，并按列表append()方法将值添加到其中。

演示：

>>> numbers = [1, 2, 3]
>>> result = []
>>> for i in numbers:
...   result.append(i*2)
... 
>>> result
[2, 4, 6]
>>> 

Answer 3

如果您想将结果收集到列表中，只需创建一个列表并在其中append：

numbers = [1, 2, 3]
doubles = []
for number in numbers:
    double = number * 2 
    doubles.append(double)

...或者更紧凑的是，对列表理解做同样的事情：

numbers = [1, 2, 3]
doubles = [number * 2 for number in numbers]