On Dec 10, 2007 8:24 AM, Tim Bowden <[EMAIL PROTECTED]> wrote:
>
> On Mon, 2007-12-10 at 13:14 +0000, Beginner wrote:
> > Hi,
> >
> > I have a huge XML file, 1.7GB, 53080215 lines. I am trying to extract
> > an attribute from each record (code=). I several problems one of
> > which is the size of the file is making it painful to test my scripts
> > and methods for parsing.
> >
> > I would like to extract a few hundred records (by any means) so I can
> > experiment. I think XPath is the way to go here. The file
> > (currently) sits on a *nix system but I was going to do the parsing
> > to on a Win32 workstation rather than steal all the memory on a
> > server.
> If your data file is on a *nix system, use
> head -200 filename > sample_filename to take the first 200 records.
snip
Unfortunately that won't work with structured data like XML. You best
bet is to use something like XML::Twig to grab the top level records
and output them to a new file. for instance, say we have an XML file
that looks like this
<root>
<records set="1">
<record>foo</record>
<record>bar</record>
<record>baz</record>
</records>
<records set="2">
<record>quux</record>
</records>
<records set="3">
<record>foofoo</record>
<record>foobar</record>
</records>
</root>
and we only want the first two sets of records. We could use this
code to produce a new file with only those records
#!/usr/bin/perl
use strict;
use warnings;
use XML::Twig;
my $i;
my $t = XML::Twig->new(
twig_handlers => {
records => sub {
exit if ++$i > 2;
$_->print;
$_->flush;
}
}
);
print "<root>";
$t->parsefile("t.xml");
print "</root>";
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