perl - record seperator

by: Fero45Posted on 2009-10-15 at 11:24:50ID: 25583297

Supposing you want to process the contents ;ike this
One
two
three
number of tasks=
four
five
six
seven
number of tasks=
eight

Try this:

open FILE, 'my_file' or die $!;
while(<FILE>)	{
	chomp;
# check if the line contains this string:
	if( $_ =~ m/number of tasks/ )	{
		print "\n";
		next();
	}
	print $_ . "\n";
}
 
# You should get each record separated by a blank line like this:
One
two
three
 
four
five
six
seven
 
eight

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by: bt707Posted on 2009-10-15 at 11:35:38ID: 25583403

Hi Fero45,

I can seperate the records with a blank line and do something as you show, that will work but what I'm trying to do is learn something and figure out if there is a way to just sperate the records as I was doing with:

$/=" number of tasks=";

When I do seperate the records I can then just use

$/="\n\n";

is there not anyway to do this without seperating the records with a new line?

Below is a example of what I'm doing with this one, the script below prints out what I want other than it ignores the tasks= value.

#!/usr/bin/perl -w
use strict;
$/=" number of tasks=";
 
print join(qq{\t},qw{Calendar EventsModified Num-Events TasksModified Num-Tasks Cal-Created}),qq{\n};
 
while(<>) {
    next if /^\s+$/;
    my ($owner) = (/(.*?): owner=.*?\sstatus=.*/);
    my ($eventsMod) = (/events last modified=(.*\,\s\d{4})/);
    my ($numEvents) = (/number of events=(\d+)/);
    my ($taskMod) = (/todos last modified=(.*\,\s\d{4})/);
    my ($numTask) = (/number of (tasks=\d+)/);
    my ($calCreated) = (/created=(.*\,\s\d{4})/);
print qq{$owner\t} if $owner;
print qq{$eventsMod\t} if $eventsMod;
print qq{$numEvents\t} if $numEvents;
print qq{$taskMod\t} if $taskMod;
print qq{$numTask\t} if $numTask;
print qq{$calCreated\n} if $calCreated;
 
}

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by: David_BothamPosted on 2009-10-16 at 06:19:21ID: 25589191

bt707,

From the 'perlvar' man page:

"The input record separator, newline by default. This influences Perl's idea of what a "line" is. Works like awk's RS variable, including treating empty lines as a terminator if set to the null string. (An empty line cannot contain any spaces or tabs.) You may set it to a multi-character string to match a multi-character terminator, or to undef to read through the end of file. Setting it to "\n\n" means something slightly different than setting to "", if the file contains consecutive empty lines. Setting to "" will treat two or more consecutive empty lines as a single empty line. Setting to "\n\n" will blindly assume that the next input character belongs to the next paragraph, even if it's a newline. (Mnemonic: / delimits line boundaries when quoting poetry.)

local $/; # enable "slurp" mode
local $_ = <fh>; # whole file now here
s/\n[ \t]+/ /g;

Remember: the value of $/ is a string, not a regex. awk has to be better for something. :-)"

What you are looking to do is not supported. So, it is probably best to encapsulate your End Of Record logic in a subroutine, and call it in your file loop iterator, as shown below.

David
</fh>

#!/usr/bin/perl -w
use strict;
 
# Sub to find our end of record, and return the task number.
sub end_of_record {
    my $field = shift;
 
    if ($field =~ m{task\s+number\s*=\s*(\d+)}xms) {
        return $1;
    }
    # If not EOR, always return with a bare return to ensure falseness, even if caller
    # assigns return value to an array...
    return;
}
 
 
while (my $field = <>) {
    chomp $field;
    my $task_number = end_of_record($field);
    if ($task_number) {
        print "Task Number = $task_number\n\n\n";
    }
    else {
        print "$field\n";
    }
}

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by: FishMongerPosted on 2009-10-16 at 07:06:04ID: 25589671

I'd probably use the flip-flop operator to loop over the lines in each record.

Here's a simple example.

#!/usr/bin.perl
 
use warnings;
use strict;
use Data::Dumper;
 
my %record;
my $num = 1;
 
while ( <DATA> ) {
    if (/start/ .. /end/ ) {
 
        # I'm simply putting the records into a hash
        $record{"record:$num"} .= $_;
 
        # increment the record number if we reach its end
        ++$num if /end/;
    }
}
print Dumper \%record;
 
__DATA__
start
5dbd
ajgh
jyhd
53
end
start
.,feg
brnyk4y
bdb76in
weg
end

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by: FishMongerPosted on 2009-10-16 at 07:36:49ID: 25589952

In case that flip-flop example wasn't clear enough for your needs, here's one that processes your data.

(This is untested, so it may need a slight tweak)

#!/usr/bin.perl
 
use warnings;
use strict;
 
my %record;
my @fields = qw( Calendar EventsModified Num-Events TasksModified Num-Tasks Cal-Created );
 
print join(qq{\t}, @fields, qq{\n};
 
while ( <> ) {
    chomp;
    if (/start/ .. /end/ ) {
        $record{Calendar}       = $1 if /(.*?): owner=.*?\sstatus=.*/;
        $record{EventsModified} = $1 if /events last modified=(.*\,\s\d{4})/;
        $record{Num-Events}     = $1 if /number of events=(\d+)/;
        $record{TasksModified}  = $1 if /todos last modified=(.*\,\s\d{4})/;
        $record{Num-Tasks}      = $1 if /number of (tasks=\d+)/;
        $record{Cal-Created}    = $1 if /created=(.*\,\s\d{4})/;
        
        if ( /end/ ) {
            print join("\t", @record{@fields}), "\n";
            undef %record;
        }
    }
}

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by: bt707Posted on 2009-10-16 at 07:42:41ID: 31642119

FishMonger,

Yes the 1st example was clear, was just thinking about it and looks to be just what I need and was asking for.

The other post was good but was the same as I was already doing and reverting back to separating the records with a new line, which will work but did not want to do that.

Thank you for the help, I couldn't add the whole script as I have a number of other functions in the loop which is quite long and also contains Co. info that I cannot post.

Thanks for the help to all.

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perl - record seperator

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