$ cat pm1080886.pl #!/usr/bin/perl use strict; use warnings; use Data::Dumper; my @hd = ( [] ); my $a = [0.25]; my $b = [0.25, 0.5]; push @hd, $a; push @hd, $b; print Dumper(\@hd); exit; __END__ $ ./pm1080886.pl $VAR1 = [ [], [ '0.25' ], [ '0.25', '0.5' ] ];