in reply to random index in array - no duplicates

another thing (not optimized but i hope clear enough) not exactly for the same use (i needed to keep the values of a column) so it is more an array to anonymise some labels. i use it for blind tests 
my @tab_anonyme;
for $i (0..$#my_data) {
    $tab_anonyme[$i][0] =  $my_data[$i][0]; # data to keep
    $tab_anonyme[$i][1] = int ( rand (100) ) + 1; # anonyme label
}
# verification
my $flag_duplicate;

do {
    $flag_duplicate = "false";
    for $i (0..$#tab_anonyme) {
        for $i2 (0..$#tab_anonyme) {
            if ($i2 == $i) { next; } # no testing of a value against i
+tself
            if ( $tab_anonyme[$i][1] == $tab_anonyme[$i2][1] ) {
                $tab_anonyme[$i2][1] = int ( rand (100) ) + 1;
                $flag_duplicate = "true";
            }
        }                
    }
} while ( $flag_doublon eq "true" );

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two problems

- in rand(X), if X is smaller than the number of lines of the array @mydata => infinite loop, make it four or five time bigger

- time taken is not very predictible

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Re^2: random index in array - no duplicates
by Anonymous Monk on Jul 08, 2016 at 13:41 UTC

    The answer is still shuffle. Your problem can be broken down in two parts: (1) constructing a list of random labels; (2) assembling the required data structure. Shuffle solves the first part, tutorials (perldsc, perllol) for working with structured data may help you with the latter.

    use List::Util qw( shuffle );

my @data = map { [$_, undef] } qw( v1 v2 v3 v4 v5 );

my @shuf = shuffle 0..$#data;

my @tab = map { [$data[$_][0], $shuf[$_]] } 0..$#data;

use Data::Dumper;
print Data::Dumper->Dump([\@data, \@tab], [qw(*data *tab)]);

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    Please, if you need help or advice with your programming tasks, post them as new questions in Seekers of Perl Wisdom.

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