http://qs321.pair.com?node_id=707243


in reply to greater efficiency required (ls, glob, or readdir?)

For efficiency you want something like this: 

my $dir = '/Path/to/a/data/directory';

opendir my $DH, $dir or die "Cannot open '$dir' $!";

my %hash;
while ( my $file = readdir $DH ) {
    next if $file =~ /~$/;
    open my $FH, '<', "$dir/$file" or die "Cannot open '$dir/$file' $!
+";
    while ( my $line = <$FH> ) {
        next if /^#/ || !/\S/;
        my ( $key, @values ) = split /\t/;
        $hash{ $file }{ $key } = \@values;
    }
}

[download]

Update: I realised that the while loop is incorrect, it should be: 

    while ( my $line = <$FH> ) {
        next if $line =~ /^#/ || $line !~ /\S/;
        my ( $key, @values ) = split /\t/, $line;
        $hash{ $file }{ $key } = \@values;
    }

[download]

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Re^2: greater efficiency required (ls, glob, or readdir?)
by linuxer (Curate) on Aug 27, 2008 at 19:09 UTC

    what about skipping the directory entries?

    my $dir = '/Path/to/a/data/directory';

opendir my $DH, $dir or die "Cannot open '$dir' $!";

my %hash;
while ( my $file = readdir $DH ) {

    next if $file =~ /~$/;
    next if -d "$dir/$file";                       # should also skip 
+'.' and '..' entries

    # read and process file
}

    [download]

    update: fix path issue "$dir/$file"

[reply]
[d/l]
Re^2: greater efficiency required (ls, glob, or readdir?)
by jperlq (Acolyte) on Aug 27, 2008 at 20:09 UTC
    Thanks, I got your version to work with very few changes. 
        my $dir = '/path/to/data/directory';  
    my %hash;
    opendir my $DH, $dir or die "cannot open '$dir' $!";
    while (my $file = readdir $DH ) {
        next if $file =~ /~$/;
        next if -d $file;
        open my $FH, "<", "$dir/$file" or die "Cannot open '$dir/$file
+' $!";
        while ( my $line = <$FH> ) {
            next if /^#/ || !length($line);
            my ($key, @values ) = split(/\t/, $line);
            $hash{ $file }{ $key } = \@values;
        }
    }

    [download]
    It even seems to work quite a bit faster than the ls/cat combo.
[reply]
[d/l]

      You need to change: next if -d $file; to next if -d "$dir/$file";

      You need to change: next if /^#/ || !length($line); to next if $line =~ /^#/ || !length($line);

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[d/l]
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