[30363] in Perl-Users-Digest
Perl-Users Digest, Issue: 1606 Volume: 11
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Tue Jun 3 11:14:24 2008
Date: Tue, 3 Jun 2008 08:14:15 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Tue, 3 Jun 2008 Volume: 11 Number: 1606
Today's topics:
XML::Parser Tree Style <NiallBCarter@googlemail.com>
Re: XML::Parser Tree Style <devnull4711@web.de>
Re: XML::Parser Tree Style <NiallBCarter@googlemail.com>
Re: XML::Parser Tree Style <devnull4711@web.de>
Re: XML::Parser Tree Style <NiallBCarter@googlemail.com>
Re: XML::Parser Tree Style <1usa@llenroc.ude.invalid>
Re: XML::Parser Tree Style <NiallBCarter@googlemail.com>
Re: XML::Parser Tree Style <1usa@llenroc.ude.invalid>
Re: XML::Parser Tree Style <NiallBCarter@googlemail.com>
Re: XML::Parser Tree Style <tzz@lifelogs.com>
Re: XML::Parser Tree Style <benkasminbullock@gmail.com>
Re: XML::Parser Tree Style <NiallBCarter@googlemail.com>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Tue, 3 Jun 2008 02:49:56 -0700 (PDT)
From: NiallBCarter <NiallBCarter@googlemail.com>
Subject: XML::Parser Tree Style
Message-Id: <6424ae77-3a79-4a20-810a-05e210c6b610@d45g2000hsc.googlegroups.com>
Hi guys and gals
So I am a little new to XML::Parser but I have read the docs and PODs
and know that this module has what I need but I am a little stuck on
implementation.
I have this XML:
<?xml version='1.0' encoding='UTF-8'?>
<list name="Nialls list">
<person>
<firstname>Niall</firstname>
<lastname>Carter</lastname>
<age>24</age>
</person>
<person>
<firstname>Ruth</firstname>
<lastname>Brewster</lastname>
<age>22</age>
</person>
<person>
<firstname>Cas</firstname>
<lastname>Creer</lastname>
<age>23</age>
</person>
</list>
and I have this perl script:
#!/usr/bin/perl
use XML::Parser;
use Data::Dumper;
use strict;
use warnings;
$parser = new XML::Parser( Style => 'Tree' );
my $tree = $parser->parsefile( 'testxml.xml' );
print Dumper( $tree );
which prints the contents of the xml to the screen. However what I
really want to do is Parse through the file taking out each firstname
and putting them in an array. At the very least I would quite like to
just know how to 'get at' to a node.
The $tree - is it an array? a scalar? a variable? little confused
there you see. If it is a scalar, how do I get access to it?
Thanks in advance
------------------------------
Date: Tue, 03 Jun 2008 12:03:06 +0200
From: Frank Seitz <devnull4711@web.de>
Subject: Re: XML::Parser Tree Style
Message-Id: <6akj7hF38g0l2U2@mid.individual.net>
NiallBCarter wrote:
>
> The $tree - is it an array? a scalar? a variable? little confused
> there you see. If it is a scalar, how do I get access to it?
Did you read the doc?
http://search.cpan.org/~msergeant/XML-Parser-2.36/Parser.pm#Tree
Frank
--
Dipl.-Inform. Frank Seitz; http://www.fseitz.de/
Anwendungen für Ihr Internet und Intranet
Tel: 04103/180301; Fax: -02; Industriestr. 31, 22880 Wedel
------------------------------
Date: Tue, 3 Jun 2008 03:18:52 -0700 (PDT)
From: NiallBCarter <NiallBCarter@googlemail.com>
Subject: Re: XML::Parser Tree Style
Message-Id: <2dbeee9b-cfc1-45de-9569-6f925761a634@b1g2000hsg.googlegroups.com>
On Jun 3, 11:03 am, Frank Seitz <devnull4...@web.de> wrote:
> NiallBCarter wrote:
>
> > The $tree - is it an array? a scalar? a variable? little confused
> > there you see. If it is a scalar, how do I get access to it?
>
> Did you read the doc?
>
> http://search.cpan.org/~msergeant/XML-Parser-2.36/Parser.pm#Tree
Many many times. So the tree parse is an array reference but does not
describe how to get the information out of it. I am very surprised by
the lack of tutorials about this. Many of them use handlers and event
(or stream) processing which I clearly want to stay away from.
I have previously used XML::Simple and thought that I could use:
my $var =3D $tree->{person}->{firstname}
but that (i think I am correct in saying) is how you access a Hash?
>
> Frank
> --
> Dipl.-Inform. Frank Seitz;http://www.fseitz.de/
> Anwendungen f=FCr Ihr Internet und Intranet
> Tel: 04103/180301; Fax: -02; Industriestr. 31, 22880 Wedel
------------------------------
Date: Tue, 03 Jun 2008 12:29:29 +0200
From: Frank Seitz <devnull4711@web.de>
Subject: Re: XML::Parser Tree Style
Message-Id: <6akkovF38g0l2U3@mid.individual.net>
NiallBCarter wrote:
> On Jun 3, 11:03 am, Frank Seitz <devnull4...@web.de> wrote:
>>
>>Did you read the doc?
>>
>>http://search.cpan.org/~msergeant/XML-Parser-2.36/Parser.pm#Tree
>
> Many many times. So the tree parse is an array reference but does not
> describe how to get the information out of it. I am very surprised by
> the lack of tutorials about this. Many of them use handlers and event
> (or stream) processing which I clearly want to stay away from.
> I have previously used XML::Simple and thought that I could use:
> my $var = $tree->{person}->{firstname}
> but that (i think I am correct in saying) is how you access a Hash?
Yes, the representation is a little complicated.
Maybe this module makes it easier for you:
http://search.cpan.org/~ebohlman/XML-Parser-EasyTree-0.01/EasyTree.pm
Frank
--
Dipl.-Inform. Frank Seitz; http://www.fseitz.de/
Anwendungen für Ihr Internet und Intranet
Tel: 04103/180301; Fax: -02; Industriestr. 31, 22880 Wedel
------------------------------
Date: Tue, 3 Jun 2008 04:04:59 -0700 (PDT)
From: NiallBCarter <NiallBCarter@googlemail.com>
Subject: Re: XML::Parser Tree Style
Message-Id: <4a82009c-97f5-4bf6-a20e-f157932bcaa9@y21g2000hsf.googlegroups.com>
On Jun 3, 11:29 am, Frank Seitz <devnull4...@web.de> wrote:
> NiallBCarter wrote:
> > On Jun 3, 11:03 am, Frank Seitz <devnull4...@web.de> wrote:
>
> >>Did you read the doc?
>
> >>http://search.cpan.org/~msergeant/XML-Parser-2.36/Parser.pm#Tree
>
> > Many many times. So the tree parse is an array reference but does not
> > describe how to get the information out of it. I am very surprised by
> > the lack of tutorials about this. Many of them use handlers and event
> > (or stream) processing which I clearly want to stay away from.
> > I have previously used XML::Simple and thought that I could use:
> > my $var = $tree->{person}->{firstname}
> > but that (i think I am correct in saying) is how you access a Hash?
>
> Yes, the representation is a little complicated.
> Maybe this module makes it easier for you:
>
> http://search.cpan.org/~ebohlman/XML-Parser-EasyTree-0.01/EasyTree.pm
>
I have looked into EasyTree and it does not satisfy my demands later
on. I also do not manage the computer I work on and so installing
extra modules is not simple and very time consuming. I would rather
stick to XML::Parser.
Any help on how to access the data out of the array?
------------------------------
Date: Tue, 03 Jun 2008 11:49:22 GMT
From: "A. Sinan Unur" <1usa@llenroc.ude.invalid>
Subject: Re: XML::Parser Tree Style
Message-Id: <Xns9AB24F91D3B1Easu1cornelledu@127.0.0.1>
NiallBCarter <NiallBCarter@googlemail.com> wrote in news:6424ae77-3a79-
4a20-810a-05e210c6b610@d45g2000hsc.googlegroups.com:
> and I have this perl script:
>
> #!/usr/bin/perl
>
> use XML::Parser;
> use Data::Dumper;
> use strict;
> use warnings;
>
> $parser = new XML::Parser( Style => 'Tree' );
> my $tree = $parser->parsefile( 'testxml.xml' );
>
> print Dumper( $tree );
When you post code, it is assumed that it is the code you have run and
tested. When you include use strict in the code you posted, you lead
people to assume that the code you have posted compiles under use
strict.
Well, that is certainly not true of the code above. Please do not
intentionally mislead your readers by posting code you have not run
yourself. Do not add in use strict as a cosmetic touch. Do read the
posting guidelines and follow them.
...
> which prints the contents of the xml to the screen. However what I
> really want to do is Parse through the file taking out each firstname
> and putting them in an array.
Well, why don't you do what you really want then?
> At the very least I would quite like to
> just know how to 'get at' to a node.
That is a different question.
> The $tree - is it an array? a scalar? a variable? little confused
> there you see. If it is a scalar, how do I get access to it?
What did you see when you looked at the output of Dumper $tree?
Here is your fish:
#!/usr/bin/perl
use XML::Parser;
use Data::Dumper;
use strict;
use warnings;
my $parser = new XML::Parser( Style => 'Stream' );
$parser->parse( \*DATA );
my $in_firstname = 0;
sub StartTag { $in_firstname = 1 if $_ eq '<firstname>' }
sub EndTag { $in_firstname = 0 if $_ eq '</firstname>' }
sub Text { print "$_\n" if $in_firstname }
__DATA__
<?xml version='1.0' encoding='UTF-8'?>
<list name="Nialls list">
<person>
<firstname>Niall</firstname>
<lastname>Carter</lastname>
<age>24</age>
</person>
<person>
<firstname>Ruth</firstname>
<lastname>Brewster</lastname>
<age>22</age>
</person>
<person>
<firstname>Cas</firstname>
<lastname>Creer</lastname>
<age>23</age>
</person>
</list>
> Thanks in advance
Sinan
--
A. Sinan Unur <1usa@llenroc.ude.invalid>
(remove .invalid and reverse each component for email address)
comp.lang.perl.misc guidelines on the WWW:
http://www.rehabitation.com/clpmisc/
------------------------------
Date: Tue, 3 Jun 2008 05:56:16 -0700 (PDT)
From: NiallBCarter <NiallBCarter@googlemail.com>
Subject: Re: XML::Parser Tree Style
Message-Id: <389dd854-2da8-47f1-9453-3ceb768aae9c@k37g2000hsf.googlegroups.com>
> Well, why don't you do what you really want then?
>
> > At the very least I would quite like to
> > just know how to 'get at' to a node.
>
> That is a different question.
>
> > The $tree - is it an array? a scalar? a variable? little confused
> > there you see. If it is a scalar, how do I get access to it?
>
> What did you see when you looked at the output of Dumper $tree?
>
> Here is your fish:
>
> #!/usr/bin/perl
>
> use XML::Parser;
> use Data::Dumper;
> use strict;
> use warnings;
>
> my $parser = new XML::Parser( Style => 'Stream' );
> $parser->parse( \*DATA );
>
> my $in_firstname = 0;
>
> sub StartTag { $in_firstname = 1 if $_ eq '<firstname>' }
>
> sub EndTag { $in_firstname = 0 if $_ eq '</firstname>' }
>
> sub Text { print "$_\n" if $in_firstname }
>
Well, many thanks but you did not answer a single question of mine.
You are correct, the script I put did not run. this was my fault it
was meant to be:
#!/usr/bin/perl
use strict;
use warnings;
use XML::Parser;
use Data::Dumper;
my $p = new XML::Parser( Style => 'Tree' );
my $inputfile = "testxml.xml";
my $tree = $p->parsefile($inputfile);
print Dumper( $tree );
> What did you see when you looked at the output of Dumper $tree?
When this runs I see:
$VAR1 = [
'list',
[
{
'name' => 'Nialls list'
},
0,
'
',
'person',
[
{},
0,
'
',
'firstname',
[
{},
0,
'Niall'
],
0,
etc etc
This is an array reference - or so it says in the documentation.
> Well, why don't you do what you really want then?
I am not sure how or why you thought this comment helpful. Funnily
enough I have spent a lot of time having to teach myself perl and
these modules piecing together bits of help from people. This doesn't
really help does it?
> That is a different question.
So as I originally stated, could anyone help me to try to use the Tree
Style to parse out the value contained in the firstname element?
Thanks for all the replies
------------------------------
Date: Tue, 03 Jun 2008 13:39:40 GMT
From: "A. Sinan Unur" <1usa@llenroc.ude.invalid>
Subject: Re: XML::Parser Tree Style
Message-Id: <Xns9AB2624501284asu1cornelledu@127.0.0.1>
NiallBCarter <NiallBCarter@googlemail.com> wrote in news:389dd854-2da8-
47f1-9453-3ceb768aae9c@k37g2000hsf.googlegroups.com:
>
>> Well, why don't you do what you really want then?
>>
>> > At the very least I would quite like to
>> > just know how to 'get at' to a node.
>>
>> That is a different question.
>>
>> > The $tree - is it an array? a scalar? a variable? little confused
>> > there you see. If it is a scalar, how do I get access to it?
>>
>> What did you see when you looked at the output of Dumper $tree?
>>
>> Here is your fish:
>>
>> #!/usr/bin/perl
>>
>> use XML::Parser;
>> use Data::Dumper;
>> use strict;
>> use warnings;
>>
>> my $parser = new XML::Parser( Style => 'Stream' );
>> $parser->parse( \*DATA );
>>
>> my $in_firstname = 0;
>>
>> sub StartTag { $in_firstname = 1 if $_ eq '<firstname>' }
>>
>> sub EndTag { $in_firstname = 0 if $_ eq '</firstname>' }
>>
>> sub Text { print "$_\n" if $in_firstname }
>>
> Well, many thanks but you did not answer a single question of mine.
Yes it did. It showed you the answer to
>>> However what I really want to do is Parse through the
>>> file taking out each firstname and putting them in an
>>> array.
You only need a small modification to the code above to accomplish that.
You ought to be able to figure out that modification.
> When this runs I see:
> $VAR1 = [
> 'list',
> [
> {
> 'name' => 'Nialls list'
> },
> 0,
> '
> ',
> 'person',
> [
> {},
> 0,
> '
> ',
> 'firstname',
> [
> {},
> 0,
> 'Niall'
> ],
> 0,
> etc etc
> This is an array reference - or so it says in the documentation.
Yes it is. And you can access individual elements just as with any other
array reference. Then you can access individual elements contained in
that reference so on and so forth.
What is the point though? First of all, doing so requires the tree
representation of the whole file to be constructed in memory which is
wasteful and will likely cause trouble if the file is large. Second, it
is tedious to write code for that style. But, if you want, you can.
For example:
print $tree->[1]->[4]->[4]->[2], "\n";
should print Niall.
> So as I originally stated, could anyone help me to try to use the Tree
> Style to parse out the value contained in the firstname element?
Why do you want to use the tree style to parse out the text of one type
of element?
> Thanks for all the replies
You are very welcome.
Sinan
--
A. Sinan Unur <1usa@llenroc.ude.invalid>
(remove .invalid and reverse each component for email address)
comp.lang.perl.misc guidelines on the WWW:
http://www.rehabitation.com/clpmisc/
------------------------------
Date: Tue, 3 Jun 2008 06:54:40 -0700 (PDT)
From: NiallBCarter <NiallBCarter@googlemail.com>
Subject: Re: XML::Parser Tree Style
Message-Id: <d07ef9ec-3ff3-46cd-b9f5-fca8a00c4aad@t54g2000hsg.googlegroups.com>
> Yes it is. And you can access individual elements just as with any other
> array reference. Then you can access individual elements contained in
> that reference so on and so forth.
>
> What is the point though? First of all, doing so requires the tree
> representation of the whole file to be constructed in memory which is
> wasteful and will likely cause trouble if the file is large. Second, it
> is tedious to write code for that style. But, if you want, you can.
>
> For example:
>
> print $tree->[1]->[4]->[4]->[2], "\n";
>
> should print Niall.
>
> > So as I originally stated, could anyone help me to try to use the Tree
> > Style to parse out the value contained in the firstname element?
>
> Why do you want to use the tree style to parse out the text of one type
> of element?
>
Thanks for the replies, I very much appreciate it Sinan.
The grand picture is this:
I have three perl scripts which generate KML. One of these KML scripts
contain the tag <gml:Point>
<gml:pos>123456,123456</gml:pos>
</gml:point>
where 123456 is the Eastings and Northings of the location.
What I will need to do is parse through the KML, get the Easting and
Northing coordinates out, use them as values in an SQL statement which
returns me Latitude and Longitude values which I then want to put back
into the KML document in place of <Point>
<coordinates>,,0</coordinates>
</Point>
The space between coordinates should contain: $Lon,$lat,0
Currently I want to keep this as simple as possible and add
functionality as I learn it which is why I am boiling down to a
minimum at the moment.
Niall
I then need to merge all three KML documents into one. These KML
documents contain series of Placemarks
I have been playing with XML:Simple - which by all accounts from
anyone is just not complicated enough and also libXML which looks
quite promising.
In teh meantime as a fallback I thought hat if I could put an element
value into an array I could then construct my KML document from values
held in an array.Hope this clears things up for you (probably not) but
as I said I am a newbie who is trying to get his head around perl let
alone extra modules!
Rgds,
Niall
------------------------------
Date: Tue, 03 Jun 2008 09:03:04 -0500
From: Ted Zlatanov <tzz@lifelogs.com>
Subject: Re: XML::Parser Tree Style
Message-Id: <86prqy8vl3.fsf@lifelogs.com>
On Tue, 3 Jun 2008 04:04:59 -0700 (PDT) NiallBCarter <NiallBCarter@googlemail.com> wrote:
N> I have looked into EasyTree and it does not satisfy my demands later
N> on. I also do not manage the computer I work on and so installing
N> extra modules is not simple and very time consuming. I would rather
N> stick to XML::Parser.
N> Any help on how to access the data out of the array?
Your problem is not with XML::Parser.
Read `perldoc perlref' and understand how Perl array and hash references
work. It's essential you do that if you want to be any good at Perl.
Ted
------------------------------
Date: Tue, 3 Jun 2008 13:59:39 +0000 (UTC)
From: Ben Bullock <benkasminbullock@gmail.com>
Subject: Re: XML::Parser Tree Style
Message-Id: <g23iob$84a$1@ml.accsnet.ne.jp>
On Tue, 03 Jun 2008 05:56:16 -0700, NiallBCarter wrote:
> Well, many thanks but you did not answer a single question of mine.
That's the Way of the World here, you have to get everything right first time.
But A. Sinan Unur made several valid points about your post, so perhaps you
could try to swallow this particular bitter pill in case it does you some good.
> This is an array reference - or so it says in the documentation.
I think your problem is nothing to do with the XML parser, it's that you don't
understand Perl's references. They are quite hard to understand, but the basic
idea is like this:
my @array = (1,2,3);
my $ref = \@array; # take a reference
my $array_ref = [1,2,3];
my @get_array_back = @{ $array_ref }; # now is the same as @array
Perhaps you can find some more documentation on the internet. If you are
really desperate or a masochist, you could try "perldoc perlreftut" and
"perldoc perlref". But the best way to learn about these is to footle around
with trivial programs and see what happens.
> So as I originally stated, could anyone help me to try to use the Tree
> Style to parse out the value contained in the firstname element?
That's easy:
#!/usr/bin/perl
use strict;
use warnings;
use XML::Parser;
use Data::Dumper;
my $xml=<<EOF;
<?xml version='1.0' encoding='UTF-8'?>
<list name="Nialls list">
<person>
<firstname>Niall</firstname>
<lastname>Carter</lastname>
<age>24</age>
</person>
<person>
<firstname>Ruth</firstname>
<lastname>Brewster</lastname>
<age>22</age>
</person>
<person>
<firstname>Cas</firstname>
<lastname>Creer</lastname>
<age>23</age>
</person>
</list>
EOF
my $p = new XML::Parser( Style => 'Tree' );
my $inputfile = "testxml.xml";
my $tree = $p->parse($xml);
my $stuff = Dumper( $tree );
$stuff =~ s/\s//g;
while ($stuff =~/firstname.*?(\w+)'\]/g) {
print "$1\n";
}
Works for me.
------------------------------
Date: Tue, 3 Jun 2008 07:34:59 -0700 (PDT)
From: NiallBCarter <NiallBCarter@googlemail.com>
Subject: Re: XML::Parser Tree Style
Message-Id: <0a1c6382-4c2b-400a-afc0-9468a1413cf2@z66g2000hsc.googlegroups.com>
> That's the Way of the World here, you have to get everything right first time.
> But A. Sinan Unur made several valid points about your post, so perhaps you
> could try to swallow this particular bitter pill in case it does you some good.
Thanks for the wise words. You are right, it is bitter but has done
good.
> I think your problem is nothing to do with the XML parser, it's that you don't
> understand Perl's references. They are quite hard to understand, but the basic
> idea is like this:
>
> my @array = (1,2,3);
> my $ref = \@array; # take a reference
> my $array_ref = [1,2,3];
> my @get_array_back = @{ $array_ref }; # now is the same as @array
>
> Perhaps you can find some more documentation on the internet. If you are
> really desperate or a masochist, you could try "perldoc perlreftut" and
> "perldoc perlref". But the best way to learn about these is to footle around
> with trivial programs and see what happens.
I have (tried to have) read perlref and perlreftut. They are not easy
but I think I get the basic concepts. I will have a footle around and
try to do some examples on teh internet.
I get that $stuff and $tree are not arrays but rather refs to arrays
(right?) and fair enough. I get what's going on and seem to do well so
far. Until I get to:
$stuff =~ s/\s//g;
and:
> while ($stuff =~/firstname.*?(\w+)'\]/g) {
> print "$1\n";
From what I can gather (I have come across these before when politely
asked to STFW)
it is regarding a search and replace function?
Within my while loop there can I not just place the value in an array
so that I can take that array off to another part of my perl script
and make something of it?
Thanks for the laymans explanation - it is exactly what I needed.
>
> > So as I originally stated, could anyone help me to try to use the Tree
> > Style to parse out the value contained in the firstname element?
>
> That's easy:
>
> #!/usr/bin/perl
>
> use strict;
> use warnings;
>
> use XML::Parser;
> use Data::Dumper;
> my $xml=<<EOF;
> <?xml version='1.0' encoding='UTF-8'?>
> <list name="Nialls list">
> <person>
> <firstname>Niall</firstname>
> <lastname>Carter</lastname>
> <age>24</age>
> </person>
> <person>
> <firstname>Ruth</firstname>
> <lastname>Brewster</lastname>
> <age>22</age>
> </person>
> <person>
> <firstname>Cas</firstname>
> <lastname>Creer</lastname>
> <age>23</age>
> </person>
> </list>
> EOF
> my $p = new XML::Parser( Style => 'Tree' );
> my $inputfile = "testxml.xml";
> my $tree = $p->parse($xml);
>
> my $stuff = Dumper( $tree );
> $stuff =~ s/\s//g;
> while ($stuff =~/firstname.*?(\w+)'\]/g) {
> print "$1\n";
>
> }
>
> Works for me.
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
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To submit articles to comp.lang.perl.announce, send your article to
clpa@perl.com.
#To request back copies (available for a week or so), send your request
#to almanac@ruby.oce.orst.edu with the command "send perl-users x.y",
#where x is the volume number and y is the issue number.
#For other requests pertaining to the digest, send mail to
#perl-users-request@ruby.oce.orst.edu. Do not waste your time or mine
#sending perl questions to the -request address, I don't have time to
#answer them even if I did know the answer.
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End of Perl-Users Digest V11 Issue 1606
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