Re: min and mindex

[kcott]

The first problem here is that you haven't asked a question! Perhaps ...

• you don't understand why you're getting the output you see (which you don't show)
• you want to know how to get the expected output (which you don't specify)
• you don't understand some part of the documentation
• you want a different way to do it

Please read the guidelines in: How do I post a question effectively?

The code you've provided outputs:

1
Statistics::Descriptive::Sparse=HASH(0x7fa3510457f0)

Presumably you want:

1
0

Checking the documentation for Statistics::Descriptive, you can achieve this by changing

my $min_index = Statistics::Descriptive::Sparse->new();
$min_index -> mindex(@array1);

to

my $stat = Statistics::Descriptive::Sparse->new();
$stat->add_data(@array1);
my $min_index = $stat->mindex();

See also ++Khen1950fx's response (above) which has similar code changes.

I see a number of alternative ways of doing this (without using Statistics::Descriptive) have already been provided. Here's another one that doesn't use any modules at all and handles non-unique values and arrays of uneven lengths.

#!/usr/bin/env perl

use strict;
use warnings;

my @data = (
    [ [ 1 .. 7 ],          [ qw{a b c d e f g} ] ],
    [ [ 1 .. 7, 0 ],       [ qw{a b c d e f g} ] ],
    [ [ 1 .. 7, 0 ],       [ qw{a b c d e f g h} ] ],
    [ [ 1 .. 7, -1, 0 ],   [ qw{a b c d e f g h} ] ],
    [ [ 1 .. 7, 1 .. 7 ],  [ qw{a b c d e f g} ] ],
);

for (@data) {
    my @array1 = @{$_->[0]};
    my @array2 = @{$_->[1]};
    my $pos = -1;

    my $min_pos = ( 
        sort { $a->[0] <=> $b->[0] } map { [$_ => ++$pos] } @array1
    )[0];

    print "Array1:    @array1\n";
    print "Min value: $min_pos->[0]\n";
    print "Min index: $min_pos->[1]\n";
    print "Array2:    @array2\n";

    if ($min_pos->[1] > $#array2) {
        print "Min index outside \@array2 bounds!\n";
    }
    else {
        print 'Min index position in @array2 has value: ',
                "$array2[$min_pos->[1]]\n";
    }

    print '-' x 60, "\n";
}

Output:

$ pm_min_mindex.pl
Array1:    1 2 3 4 5 6 7
Min value: 1
Min index: 0
Array2:    a b c d e f g
Min index position in @array2 has value: a
------------------------------------------------------------
Array1:    1 2 3 4 5 6 7 0
Min value: 0
Min index: 7
Array2:    a b c d e f g
Min index outside @array2 bounds!
------------------------------------------------------------
Array1:    1 2 3 4 5 6 7 0
Min value: 0
Min index: 7
Array2:    a b c d e f g h
Min index position in @array2 has value: h
------------------------------------------------------------
Array1:    1 2 3 4 5 6 7 -1 0
Min value: -1
Min index: 7
Array2:    a b c d e f g h
Min index position in @array2 has value: h
------------------------------------------------------------
Array1:    1 2 3 4 5 6 7 1 2 3 4 5 6 7
Min value: 1
Min index: 0
Array2:    a b c d e f g
Min index position in @array2 has value: a
------------------------------------------------------------

You may find Benchmark useful for comparing the alternative solutions supplied.