http://qs1969.pair.com?node_id=11140604


in reply to Get most recent data based on a date from an array of hashes.

I work with GMT time zone dates with the YYYY-MM-DD HH:MM:SS format often. String compare with this is fine. The key is that the leading zeroes are absolutely necessary. This is actually what a date looks like in an SQLite DB.

I see many fine posts with sorting techniques if @$data is large.

Not considered yet is what happens if more than one thing happened on the "most recent date"? In my data sets, measured to the second, I would allow for this possibility (and it very likely could indeed happen). Code below shows just one way. 

#!/usr/bin/perl -w

use strict;
use Data::Dumper;
use Data::Dump qw(dump dd);

my $data  = [
      {
        'Color' => 'green',
        'Step' => 'Platform',
        'acc' => '1111',
        'Date' => '08-06-2022'
      },
      {
        'Color' => 'black',
        'Step' => 'Platform',
        'acc' => '1111',
        'Date' => '01-05-2019'
      },
      {
         'Color' => 'reddish',
         'Step' => 'Platform',
         'acc' => '1111',
         'Date' => '03-21-2021'
      },
      
      {
        'Color' => 'blue',
        'Step' => 'Platform',
        'acc' => '1111',
        'Date' => '10-11-2020'
      },
      {
        'Color' => 'white',
        'Step' => 'Platform',
        'acc' => '1111',
        'Date' => '08-06-2022'
      },
      {
        'Color' => 'red',
        'Step' => 'Platform',
        'acc' => '1111',
        'Date' => '03-21-2021'
      },
      ];


@$data = sort{my $A = $a->{Date};
              my $B = $b->{Date};
              $A =~ s/(\d+)-(\d+)-(\d+)/$3-$1-$2/;
              $B =~ s/(\d+)-(\d+)-(\d+)/$3-$1-$2/;              
                  $B cmp $A}@$data;
                  
my $most_recent_href = $data->[0];
dd $most_recent_href;

#see if there are others on same date as most recent??

foreach my $href (@$data[1..@$data-1])
{
    if ($href->{Date} eq $most_recent_href->{Date})
    {
        dd $href;
    }
    else {last;}
}

__END__
{ acc => 1111, Color => "green", Date => "08-06-2022", Step => "Platfo
+rm" }
{ acc => 1111, Color => "white", Date => "08-06-2022", Step => "Platfo
+rm" }

[download]

Replies are listed 'Best First'.
Re^2: Get most recent data based on a date from an array of hashes.
by tybalt89 (Monsignor) on Jan 19, 2022 at 16:38 UTC

    Note that max_by() can also return multiple max's if it is used in list context. 

    #!/usr/bin/perl

use strict;
use warnings;
use List::AllUtils qw( max_by );

my $data  = [
  { acc => 1111, Color => "green", Date => "08-06-2022", Step => "Plat
+form" },
  { acc => 1111, Color => "black", Date => "01-05-2019", Step => "Plat
+form" },
  { acc => 1111, Color => "reddish", Date => "03-21-2021", Step => "Pl
+atform" },
  { acc => 1111, Color => "blue", Date => "10-11-2020", Step => "Platf
+orm" },
  { acc => 1111, Color => "white", Date => "08-06-2022", Step => "Plat
+form" },
  { acc => 1111, Color => "red", Date => "03-21-2021", Step => "Platfo
+rm" },
  ];

my @mostrecent = max_by {join '', (split /-/, $_->{Date})[2,0,1] } @$d
+ata;

use Data::Dump 'dd'; dd @mostrecent;

    [download]

    Outputs: 

    (
  { acc => 1111, Color => "green", Date => "08-06-2022", Step => "Plat
+form" },
  { acc => 1111, Color => "white", Date => "08-06-2022", Step => "Plat
+form" },
)

    [download]
[reply]
[d/l]
[select]
      This is way ++cool.
      I wasn't aware of List::AllUtils or List::Utilsby in the List:: menagerie

      List::Utils
      List::MoreUtils
      List::AllUtils
      List::SomeUtils
      List::UtilsBy

[reply]

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