Find the indexes of several elements in a list

Question

I have an list of integers:

 x = [0, 1, 3, 5, 6, 7, 33, 39, 49, 51, 11, 
      32, 55, 61, 31, 44, 43, 4, 45, 30, 50, 41]

And second list that can only contain elements from x, for example: y = [44, 11, 49]

I need to find the index of each element of y in x.

Please post your expected output. Also, what if `y` contains an element that is not in `x`? — Dan, Jun 17 '20 at 14:53
x doesn't contain duplicates. y cant contain an element that in not in x. — SilverCrow, Jun 17 '20 at 14:55
This should be re-opened, linked questions concern single search while the goal here is to find several values. — cglacet, Jun 17 '20 at 15:07

score 1 · Answer 1 · answered Jun 17 '20 at 14:53

1

.index() is what you're after.

x = [0, 1, 3, 5, 6, 7, 33, 39, 49, 51, 11, 32, 55, 61, 31, 44, 43, 4, 45, 30, 50, 41]
y = [44, 11, 49]
for a in y:
    print(x.index(a))

EDIT: Provided that each element of y appears once, and only once in x.

answered Jun 17 '20 at 14:53

JimmyCarlos

1,901
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10
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score 1 · Answer 2 · answered Jun 17 '20 at 14:54

1

x = [0, 1, 3, 5, 6, 7, 33, 39, 49, 51, 11, 32, 55, 61, 31, 44, 43, 4, 45, 30, 50, 41]
y = [44, 11, 49]
indexs=[x.index(i) for i in y if i in x]
print(indexs)

Or

ind=list(map(x.index,y))
print(ind)

answered Jun 17 '20 at 14:54

MrNobody33

6,143
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Find the indexes of several elements in a list

2 Answers2