Just a data point, but an alternative way to generate the hash is to use slice assignment. It is faster than using map if %index_map is to be generated many times, e.g. across data sets.

my %index_map;
@index{@array} = (0..$#array);

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In reply to Re^2: How to Order an Array's Elements to Match Another Array's Element Order by swl
in thread How to Order an Array's Elements to Match Another Array's Element Order by ozboomer

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