I am looking to simplify a pattern. If I have a string my $x = "0.01 NaN 2.30 4.44"; then the following pattern finds the items present: 

my $r1 = qr/([Na0-9\.\-\+]+)\s+
        ([Na0-9\.\-\+]+)\s+
        ([Na0-9\.\-\+]+)\s+
        ([Na0-9\.\-\+]+)/x;

[download]

Notice that the same capture group criteria are repeated. I wonder how I may write that so it is simpler, shorter, and all on one line. Here is some pseudo-code to try to show what I am aiming for: my $r1 = qr/(?=([Na0-9\.\-\+]+)\s+){4}/

However, I've tried that and some permutations without luck: 

#!/usr/bin/perl

use strict;
use warnings;

my $x = "0.01 NaN 2.30 4.44";

# the following works as desired
my $r1 = qr/([Na0-9\.\-\+]+)\s+
        ([Na0-9\.\-\+]+)\s+
        ([Na0-9\.\-\+]+)\s+
        ([Na0-9\.\-\+]+)/x;

my ($d, $e, $f, $g) = ($x =~ m/$r1/x );
print qq($d, $e, $f, $g\n);


# the following finds the first number twice
my $r2 = qr/(?=(([Na0-9\.\-\+]+)\s*)){4}/x;

($d, $e, $f, $g) = ($x =~ m/$r2/x );
print qq($d, $e, $f, $g\n);

# the following finds a null prior to the first item
my $r3 = qr/((?=([Na0-9\.\-\+]+)\s*){4})/x;

($d, $e, $f, $g) = ($x =~ m/$r3/x );
print qq($d, $e, $f, $g\n);

exit(0);

[download]

How can I write that pattern so that the pattern it contains is repeated but not locked into the values found in the very first match? Is this a case for using recursive patterns?

In reply to Repeating a capture group pattern within a pattern by mldvx4

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