CODEWITHSUNDEEP
perl
Baiju
Baiju

Reputation: 1

Perl: Grep unique value

Basically I wanted to emulate the piped grep operation as we do in shell script, (grep pattern1 |grep pattern2) in my Perl code to make the result unique.

Below code is working, bust just wanted to know this is the right approach. Please note, I don't want to introduce a inner loop here, just for the grep part.

foreach my $LINE ( @ARRAY1 ) {
    @LINES = split /\s+/, $LINE;
    @RESULT= grep ( /$LINES[0]/, ( grep /$LINES[1]/, @ARRAY2 ) );

...

Upvotes: 0

Views: 404

Answers (3)

sandeep
sandeep

Reputation: 152

There are different ways to grep/extract unique values from array in perl.

##2) Best of all
my %hash = map { $_ , 1 } @array;
my @uniq = keys %hash;
print "\n Uniq Array:", Dumper(\@uniq);

##3) Costly process as it involves 'greping'
my %saw;
my @out = grep(!$saw{$_}++, @array);
print "\n Uniq Array: @out \n";

Upvotes: 0

Borodin
Borodin

Reputation: 126722

There is no need to cascade calls to grep -- you can simply and the conditions together

It's also worth saying that you should be using lower-case letters for your identifiers, and split /\s+/ should almost always be split ' '

Here's what I would write

for my $line ( @array1 ) {
    my @fields = split ' ', $line;
    my @result = grep { /$fields[0]/ and /$fields[1] } @array2;

    ...

}

Upvotes: 1

mpapec
mpapec

Reputation: 50637

This is basically same thing what you're doing, "for every @ARRAY2 element, check whether it matches ALL elements from @LINES" (stop as soon as any of the @LINES element does not match),

use List::Util "none";
my @RESULT= grep { my $s = $_; none { $s !~ /$_/ } @LINES } @ARRAY2;

# index() is faster for literal values
my @RESULT= grep { my $s = $_; none { index($s, $_) <0 } @LINES } @ARRAY2;

Upvotes: 1

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