I recently seen topics here that says the findall function is quite slow and I think so too most likely if I am dealing with large number of elements say hundreds of thousands or more. An example of what I want is as follows: Given an array of arrays say
[ [1] ; [3] ; [4] ; [2] ; [1, 4] ; [1, 3] ; [3, 4]; [2, 4] ; [1, 3, 4] ; [2, 3, 4] ].
Then for each element in the array I get the combinations taken (length - 1) and find its indices. For example, combinations taken 1 for [1, 4] is [1] and [4] which has indices 1 and 3 respectively in the array. Also, combinations taken 2 for [1,3,4] is [1, 3], [1, 4], and [3, 4] which has indices 6, 5, and 7 respectively. Is there an alternative for using findall function especially if you are dealing with 200,000 or more elements in the array? Thank you for any suggestion or answer.
permutations in the Combinatorics.jl package iiuc.
But if you have something of length 200,000 and you take pairs of those, good luck fitting the result in your computer’s memory.
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