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I have a nested list with depth 6. The items in the list are mathematical expressions. I want to find the positions of the unique items in the nested list. I have found the following, which works for a non-nested list:

positionDuplicates[list_] := GatherBy[Range@Length[list], list[[#]] &]

Ideally, the function would also count how many times the item is repeated in the nested list.

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  • $\begingroup$ Do you know the function "Position"? $\endgroup$
    – Daniel Huber
    Commented Aug 9 at 6:29

1 Answer 1

Reset to default
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myList = {....};

myCounts = Counts[Flatten[myList]];

hh = (myList /. myCounts);

Position[hh, 1]

Test this with

myList = Table[RandomInteger[{1, 20}], {3}, {4}, {2}, {6}, {5}]
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  • 2
    $\begingroup$ Thank you, but since the entries of the nested list are expressions, they need to be tested for equality using FullSimplify[expr1-expr2]==0 $\endgroup$
    – Morgan
    Commented Aug 9 at 5:52

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