Finding positions of minimum values in list

Question

I would like to find the positions of multiple occurrences of a minimum value in a list. For instance, for the list {1, 2, 1, 3}, I want to obtain the two positions for the occurrences of the number 1.

MinimalBy[{1, 2, 1, 3}, id (x)] gives me these occurrences, but not the positions.

Or modifying this answer: minpos[a_] := SparseArray[UnitStep[# - a]]["AdjacencyLists"] &@Min@a and then minpos[list]. — Michael E2, May 02 '19 at 03:11
Possible duplicate: https://mathematica.stackexchange.com/questions/40231/list-manipulation-position-max-value-combination — Michael E2, May 02 '19 at 03:13

kglr · Accepted Answer · 2019-05-02T04:06:34.630

6

lst = {1, 2, 1, 3};
Random`Private`PositionsOf[lst, Min @ lst]

{1, 3}

Also

 Flatten@Position[lst, Min @ lst]

{1, 3}

edited May 02 '19 at 04:06

answered May 02 '19 at 03:43

kglr

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score 3 · Answer 2 · answered Apr 26 '23 at 05:59

3

list = {1, 2, 1, 3}
PositionIndex[list][Min[list]]

{1, 3}

answered Apr 26 '23 at 05:59

Syed

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Even more appropriate for the task is: :PositionSmallest[list] – Michael Weyrauch Apr 26 '23 at 06:46
@MichaelWeyrauch You should write it as an answer. I am running v12.2.0 which is a few years old. – Syed Apr 26 '23 at 11:45

score 3 · Answer 3 · answered Apr 26 '23 at 11:57

3

o.k. as suggested by Syed, here comes my answer: As of Mathematica Version 13.2:

list={1,2,1,3}
PositionSmallest[list]

{1, 3}

Also there is:

PositionLargest[list]

{4}

answered Apr 26 '23 at 11:57

Michael Weyrauch

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I love the new PositionSmallest and PositionLargest functions---significantly cleaner syntax for this common issue. I am left scratching my head, however, as to how it took until v13.x for them to be introduced... – erfink Apr 27 '23 at 01:17

Finding positions of minimum values in list

3 Answers3