in reply to Re^6: reading a JSON object
in thread reading a JSON object

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See the FAQ How do I sort an array by (anything)?

How do I specify an arbitrary subset of these to include in the print out?

I think you are asking how to extract an arbitrary list of fields from a larger array. In that case it is just:

use strict;
use warnings;

my @bigarray = qw/a b c d e f g h i j/;
my @subset = @bigarray[2, 5, 7];

print "@subset\n";

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Which means @subset will have just those three fields from @bigarray and the output will be "c f h".

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Re^8: reading a JSON object
by anautismobserver (Sexton) on May 11, 2022 at 19:45 UTC

    Thanks. How do I generalize this to two (or more) dimensions?

    For example, the code below selects a subset of the first index (which runs from 0-5).

    How do I modify it so it also selects a subset of the second index (which runs from 0-3)?

    use strict;
use warnings;

use Data::Dumper qw(Dumper);

my $matrix;
my @matrix;

$matrix[0][0] = 00;
$matrix[1][0] = 10;
$matrix[2][0] = 20;
$matrix[3][0] = 30;
$matrix[4][0] = 40;
$matrix[5][0] = 50;

$matrix[0][1] = 01;
$matrix[1][1] = 11;
$matrix[2][1] = 21;
$matrix[3][1] = 31;
$matrix[4][1] = 41;
$matrix[5][1] = 51;

$matrix[0][2] = 02;
$matrix[1][2] = 12;
$matrix[2][2] = 22;
$matrix[3][2] = 32;
$matrix[4][2] = 42;
$matrix[5][2] = 52;
$matrix[0][3] = 03;

$matrix[1][3] = 13;
$matrix[2][3] = 23;
$matrix[3][3] = 33;
$matrix[4][3] = 43;
$matrix[5][3] = 53;

print Dumper \@matrix;

my @matrix2 = @matrix[0, 2];
print Dumper \@matrix2;

my @matrix3 = @matrix[0, 1, 5];
print Dumper \@matrix3;

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[d/l]

      I'm not quite sure what you're asking, but maybe this will give some insight: 

      Win8 Strawberry 5.8.9.5 (32)  Wed 05/11/2022 18:46:44
C:\@Work\Perl\monks
>perl

use strict;
use warnings;

use Data::Dump qw(dd);

my @matrix = (
    [ qw(00 01 02 03) ],
    [ qw(10 11 12 13) ],
    [ qw(20 21 22 23) ],
    [ qw(30 31 32 33) ],
    [ qw(40 41 42 43) ],
    [ qw(50 51 52 53) ],
    );
# dd \@matrix;  # for debug

my @row_set = (0, 2);
my @col_set = (3, 0, 1);

for my $ar_entry (@matrix[ @row_set ]) {
    printf "'%s' '%s' '%s' \n", @{$ar_entry}[ @col_set ];
    }

for my $i_row (@row_set) {
    printf "row %d: '%s' '%s' '%s' \n", $i_row, @{ $matrix[$i_row] }[ 
+@col_set ];
    }

my @sub_matrix = map { [ @{ $_ }[ @col_set ] ] } @matrix[ @row_set ];
# my @sub_matrix = map [ @{ $_ }[ @col_set ] ], @matrix[ @row_set ];
dd \@sub_matrix;

^Z
'03' '00' '01'
'23' '20' '21'
row 0: '03' '00' '01'
row 2: '23' '20' '21'
[["03", "00", "01"], [23, 20, 21]]

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