Exclude elements of a list that are in another array

Question

I'd like to create an array like this @exclude = ("[INFO] Reading file", "[INFO] All file(s) read"); which contains items that I would like to ignore while looping through another array

The other array is @nyuulog which I've ready into from a file and looks similar to this:

[INFO] Uploading 37 article(s) from 3 file(s) totalling 23.98 MiB```
[INFO] Reading file 157.1.1.par2...
[INFO] Reading file 159.1.1.rar...
[INFO] Reading file 159.1.1.vol0+1.par2...
[INFO] All file(s) read...
[INFO] Finished uploading 23.98 MiB in 00:00:16.083 (1527.03 KiB/s). Raw upload: 2613.34 KiB/s

So I'm using this:

foreach $line(@nyuulog) {print $txtfile("$line\n");}

which writes all of the lines but I'm wanting to not write lines out to the filehandle that contains an element in the @exclude array.

Is there an easy way to do this? I've tried numerous attempts at using grep or the new Perl ~~ command (which I don't think applies in this situation) and can't get the right combination of commands.

Any help or pointing me in the right direction - would be greatly appreciated.

Thank you

Answer 1

Construct a look-up hash for what's to be excluded, and filter the array with it

my %excl = map { $_ => 1 } @exclude;

my @filtered = grep { not $excl{$_} } @original; 

This is about as efficient as list processing can be, O(N) , and hopefully clear and easy.

Can also have it in a do block to avoid an extra variable ( %excl ) floating around

my @filtered = do { 
    my %excl = map { $_ => 1 } @exclude;
    grep { not $excl{$_} } @original;
};

Answer 2

Try this:

my $FilterRe = join("|", map({"(^\Q$_\E)"} @exclude));
my @Filtered = grep({!/$FilterRe/} @nyuulog);

Inspired by a question on perlmonks .