本文介绍了如何获取项目在列表中的位置?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在遍历列表，如果满足特定条件，我想打印出该项目的索引.我该怎么办?
I am iterating over a list and I want to print out the index of the item if it meets a certain condition. How would I do this?
示例:
testlist = [1,2,3,5,3,1,2,1,6]
for item in testlist:
if item == 1:
print position
推荐答案
嗯.这里有一个列表理解的答案，但它消失了.
Hmmm. There was an answer with a list comprehension here, but it's disappeared.
这里:
[i for i,x in enumerate(testlist) if x == 1]
示例:
>>> testlist
[1, 2, 3, 5, 3, 1, 2, 1, 6]
>>> [i for i,x in enumerate(testlist) if x == 1]
[0, 5, 7]
更新:
好的，您需要一个生成器表达式，我们将有一个生成器表达式.再次在for循环中，这是列表理解:
Okay, you want a generator expression, we'll have a generator expression. Here's the list comprehension again, in a for loop:
>>> for i in [i for i,x in enumerate(testlist) if x == 1]:
... print i
...
0
5
7
现在我们将构造一个生成器...
Now we'll construct a generator...
>>> (i for i,x in enumerate(testlist) if x == 1)
<generator object at 0x6b508>
>>> for i in (i for i,x in enumerate(testlist) if x == 1):
... print i
...
0
5
7
非常有趣的是，我们可以将其分配给变量，然后从那里使用它...
and niftily enough, we can assign that to a variable, and use it from there...
>>> gen = (i for i,x in enumerate(testlist) if x == 1)
>>> for i in gen: print i
...
0
5
7
想想我曾经写过FORTRAN.
And to think I used to write FORTRAN.
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