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filtering - How to get the indices of values in a list which are NOT an specific integer?


I got a real array A, where Dimensions[A] == {5000, 5000, 5}.


Some of the values in A are -1, others are not.


How can I use Position[] to find the indices of those values which are not -1?



Answer



A = Table[If[Round@# == -1, -1, #] &[RandomReal[{-2, 0}]], {5}, {5}]

{{-1, -1.85034, -0.063618, -1.97166, -1.98232},

 {-1, -0.407057, -1.72254, -1.5231, -1.99315},
 {-1, -1, -1, -1.98979, -1},
 {-1, -1, -0.134094, -1.92523, -1.90799},
 {-0.304344, -1, -1, -1.91487, -1.66092}}

SparseArray[A, Automatic, -1]["NonzeroPositions"]

{{1,2}, {1,3}, {1,4}, {1,5}, {2,2}, {2,3}, {2,4}, {2,5}, {3,4}, {4,3}, {4,4}, {4,5}, {5,1}, {5,4}, {5,5}}

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