perldoc -f split

##</code><code>##

open ALL, "alltrans.csv" or die "Can not open file: $!";
while (<ALL>) {
    chomp;
    push @alltrans, [ split /,/, $_, -1 ];
}
close ALL;

##</code><code>##

my @alltrans;
chomp, push @alltrans, [ split /,/, $_, -1 ] for <ALL>;

# or

my @alltrans = map { chomp; [ split /,/, $_, -1 ] } <DATA>;