Reading a Flat File and Extracting Data

mantra2006 has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Reading a Flat File and Extracting Data by davorg (Chancellor) on Jan 18, 2007 at 15:14 UTC
If (as it appears) your data is in fixed width format, then you'll almost certainly find unpack to be useful - along with the "pack" tutorial. -- <http://dave.org.uk> "The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg	[reply]
Re: Reading a Flat File and Extracting Data by ferreira (Chaplain) on Jan 18, 2007 at 15:11 UTC
Take a look at AnyData, especially AnyData::Format::Fixed. This can be accessed also via a DBI interface with DBD::AnyData.	[reply]
Re: Reading a Flat File and Extracting Data by BrowserUk (Patriarch) on Jan 18, 2007 at 15:18 UTC
Use the simplest tool available unless you know you have a reason for reaching for the big guns. I've had to guess where the fields are: `c:\>p1 Perl> $line = '00UPDATE2006121509200120061215095000000000058Version 02 +.7.0.0';; Perl> @fields = unpack 'A2 A6 A10 A4 A10 A13 A*', $line;; Perl> print for @fields;; 00 UPDATE 2006121509 2001 2006121509 5000000000058 Version 02.7.0.0` [download] Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."	[reply] [d/l]
Re: Reading a Flat File and Extracting Data by Moron (Curate) on Jan 18, 2007 at 15:50 UTC
Provided the fields really are in fixed positions, the unpack idea given by BrowserUK looks very apt. If that isn't the case (for example LONGERNAME can be instead of UPDATE) , I'd make a sequence of regexp rules to match on a what-comes-next basis and iterate on it, something like: `my $fieldSpec = [ { name => "name1", pattern => '\d{2}' }, { name => "trtype", pattern => '\D+' }, { name => "timestamp", pattern => '\d{8}' }, # etc. ]; my $results = []; open my $fh, "<$file" or die $!; while( <$fh> ) { my $result = {}; for my $elt ( @$fieldspec ) { my $pat = $elt -> { pattern }; /^($pat)(.)$/ or die "unexpected format $_ at $."; $result -> { name } = $elt -> { name }; $result -> { value } = $1; $_ = $2; } push @$results, $result; }` [download] ...producing results as a reference to an array of hash in this particular example -M Free your mind*	[reply] [d/l]