I need to add unique elements in an array from inputs which contain several duplicate values.
How do I avoid pushing duplicate values into an Perl array?
3 Answers
push(@yourarray, $yourvalue) unless grep{$_ == $yourvalue} @yourarray;
This checks if the value is present in the array before pushing. If the value is not present it will be pushed.
If the value is not numeric you should use eq instead of ==.
2 Comments
Aquaholic
Above Answer is right, but it does not work if $_ is used in above/below statement, like chomp($_) while reading from a file. The following: " push(@yourarray, $yourvalue) unless $yourvalue ~~ @yourarray; " works perfectly.
You simply need to use hash like this:
my %hash;
$hash{$key} = $value; # you can use 1 as $value
...
This will automatically overwrite duplicate keys.
When you need to print it, simply use:
foreach my $key (keys %hash) {
# do something with $key
}
If you need to sort keys, use
foreach my $key (sort keys %hash) ...
1 Comment
mvp
Wow, this must be new record: answer accepted 4 years later :)
by using ~~ we can minimum perl version is 5.10.1
use v5.10.1;
use strict;
use warnings;
my @ARRAY1 = qw/This is array of backup /;
my @ARRAY2;
my $value = "version.xml";
sub CheckPush($$) {
my $val = shift (@_);
my $array_ref = shift (@_);
unless ($val ~~ @$array_ref) {
print "$val is going to push to array\n";
push(@$array_ref, $val);
}
return (@$array_ref);
}
@ARRAY1 = CheckPush($value, \@ARRAY1);
print "out\n";
foreach (@ARRAY1) {
print "$_\n";
}
@ARRAY2 = CheckPush ($value, \@ARRAY2);
print "out2\n";
foreach (@ARRAY2) {
print "$_\n";
}
2 Comments
Codr
In short:
push(@yourarray, $yourvalue) unless $yourvalue ~~ @yourarray;
brian d foy
Note that smart match was downgraded to experimental since it often acted contrary to what people expected, and had other issues.
List::MoreUtilsuniq function if you are not opposed to the CPAN.