Re^3: How to split file for threading?

If you can search the whole line without breaking it up, this:


for my $line (<INFILE>) {
    chomp $line;
    my @splitline = split("\t", $line);
    #my $poskey = $splitline[0] . ":" . $splitline[1];

    for (@splitline){
        if (/^$ARGV[1]/){
            $filter_count++;
            push(@rawfile,$line);
        }
    }
}
[download]

can become this:

while (my $line = <INFILE>) {
    chomp $line;
    if ($line =~ /^$ARGV[1]/){
        $filter_count++;
        push(@rawfile,$line);
    }
}
[download]

-stevieb

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Re^4: How to split file for threading? by afoken (Chancellor) on Jun 23, 2015 at 16:40 UTC
`while (my $line = <INFILE>) { chomp $line; if ($line =~ /^$ARGV[1]/){ $filter_count++; push(@rawfile,$line); } }` [download] A little bit more fine-tuning: If the line does not match, there is no point in chomping it. So move `chomp` into the `if` block. (This assumes the search pattern has no problems with the trailing line-end character(s) in `$line`.) Using a variable inside the regexp forces perl to recompile it several times (I think). `my $pattern=qr/^$ARGV[1]/;` in front of the `while` loop and using `$line=~$pattern` in `if` would avoid that. If the search is for a keyword at the first character of the line, and not a pattern, using a regexp may be slower than a simple string operation. Try using `if (index($line,$ARGV[1])==0)` or `if (substr($line,0,length($ARGV[1])) eq $ARGV[1])` instead. Hint: Use Devel::NYTProf to locate hot spots in your code. Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply] [d/l] [select]
Re^4: How to split file for threading? by diyaz (Beadle) on Jun 23, 2015 at 15:52 UTC
thank you!	[reply]