develooper Front page | perl.perl6.users | Postings from July 2021

Re: XML module question?

Thread Previous | Thread Next
From:
Bruce Gray
Date:
July 17, 2021 01:46
Subject:
Re: XML module question?
Message ID:
6763F4A1-4E25-4022-B476-590A19D36F63@acm.org
David,

Aha! I am very glad to be wrong!

$ raku -MXML::Writer -ne 'print XML::Writer.serialize: :wpt[ :lat(.words[5].subst(";")), :lon(.words[8]), :time[.words.head(3).join(" ")] ];'  lat_lon.txt
<wpt lat="41.858657" lon="-91.345142"><time>11-06-2014 - 10:49:06PM</time></wpt>
<wpt lat="42.864653" lon="-92.349914"><time>11-06-2014 - 10:49:49PM</time></wpt>
<wpt lat="43.874808" lon="-93.350364"><time>11-06-2014 - 10:50:35PM</time></wpt>
<wpt lat="44.885047" lon="-94.350058"><time>11-06-2014 - 10:51:21PM</time></wpt>
<wpt lat="45.895078" lon="-95.349920"><time>11-06-2014 - 10:52:08PM</time></wpt>
<wpt lat="46.905178" lon="-96.349837"><time>11-06-2014 - 10:53:30PM</time></wpt>
<wpt lat="47.910303" lon="-97.350606"><time>11-06-2014 - 10:54:50PM</time></wpt>

I do note that XML::Writer does not show up in the search at https://modules.raku.org/t/XML ,
and is very under-documented, so that is an opportunity for someone to contribute.

-- 
Hope this helps,
Bruce Gray (Util of PerlMonks)

> On Jul 16, 2021, at 2:53 PM, David Warring <david.warring@gmail.com> wrote:
> 
> The XML::Writer module side-steps any ordering issues by directly serializing data structures to xml:
> 
> $ raku -M XML::Writer -e'say XML::Writer.serialize: :wpt[ :lat<42>, :long<69>, "blah" ]'
> <wpt lat="42" long="69">blah</wpt>
> 
> On Sat, Jul 17, 2021 at 4:48 AM Bruce Gray <robertbrucegray3@gmail.com> wrote:
> > On Jul 15, 2021, at 11:02 PM, William Michels via perl6-users <perl6-users@perl.org> wrote:
> 
> (and I re-ordered):
> 
> > Any help appreciated,
> > Thanks, Bill.
> > REFERENCE:  https://unix.stackexchange.com/q/166675/227738
> 
> 
> > I'm trying to put an answer together for SO, and I keep running into the same difficulty. Given a CSV file,
> 
> Note: input is a log file, not in CSV format.
> 
> > how can one produce an XML file with latitude and longitude values properly quoted? Every time I get proper quoting, "lat" and "lon" are scrambled (i.e. sometimes "lat" first, sometimes "lat" second). 
> ...
> > using the "make-xml()" function from the XML module, I end up scrambling "lat/lon”:
> 
> You are using the correct XML module, and you are using it correctly.
> 
> Similar to a Raku hash, the attributes in an XML start-tag are *unordered*.
> While the inconsistant ordering may be displeasing to our human eyes, any program reading XML should treat your current output identically to your desired output.
> 
> In Raku-speak, these two hashes have the same contents:
>     my %wpt1 = lat => 'A', lon => 'z';
>     my %wpt2 = lon => 'z', lat => 'A’;
> 
> Designers of XML libraries are reluctant to add the ability to force an ordering; it would lead to XML-reading programs making improper assumptions.
> Like many major XML libraries in other languages, I see no such ability in the Raku XML module.
> See:
>         https://www.w3.org/TR/REC-xml/#sec-starttags
>                 Note that the order of attribute specifications
>                 in a start-tag or empty-element tag is not significant.
>         https://stackoverflow.com/questions/57756005/writing-xml-attributes-and-namespace-declarations-in-a-specific-order
>         https://community.adobe.com/t5/coldfusion/maintain-attribute-order-in-xml-with-a-structure/m-p/3838398
> 
> > Conversely, if I manage to restrict "lat/lon" to the correct order, I lose the equals sign and proper (value) quotation.
> 
> 
> Unless you just hardcode a template and insert the lat/lon/datetime values (never a good idea), you will have to live with the varying order.
> I will point out that the XML library also does not output the multi-line indentation that the OP shows; it is irrelevant in XML.
> 
> 
> > $ raku -MXML -e 'my @xml = do for lines() {make-xml("wpt", :lat(.words[5].subst(";")), :lon(.words[8]), \("time",.words[0..2]))}; .put for @xml;’  lat_lon.txt
> 
> Minor critiques:
> That use of `@array = do for lines() {…}` is more commonly written as `@array = lines().map: {…}`
>         raku -MXML -e 'my @xml = lines().map: {make-xml("wpt", :lat(.words[5].subst(";")), :lon(.words[8]), \("time",.words[0..2]))}; .put for @xml;'  lat_lon.txt
> 
> Nothing is gained by creating an array, just to print each line of the array, so your can just `put` each time you construct an XML line.
>         raku -MXML -e 'for lines() { put make-xml("wpt", :lat(.words[5].subst(";")), :lon(.words[8]), \("time",.words[0..2])) }'  lat_lon.txt
> 
> When all the output is per-line based on the input, the `-p` or `-n` flag removes the need for `for lines`.
>         raku -MXML -ne 'put make-xml("wpt", :lat(.words[5].subst(";")), :lon(.words[8]), \("time",.words[0..2]))'  lat_lon.txt
> 
> 
> 
> > So far, I can correctly swap the date/time to the end:
> > 
> > $ raku -MXML -e 'my @reordered = do for lines() {(.words[3..*],.words[0..2])}; .put for @reordered;’  lat_lon.txt
> 
> I am sure that `-MXML` is leftover from other experiments.
> Removing `@reordered` and switching to `-n` like my critiques above, this becomes:
>         raku -ne 'put (.words[3..*],.words[0..2]);' lat_lon.txt
> To “wow” the SO crowd, you might note that @array[N..*],@array[0..N-1] has a shortcut in Raku (.rotate), making this the tightest of all the solutions I see so far:
>         raku -ne 'put .words.rotate(3);'  lat_lon.txt
> 
> -- 
> Hope this helps,
> Bruce Gray (Util of PerlMonks)
> 


Thread Previous | Thread Next


nntp.perl.org: Perl Programming lists via nntp and http.
Comments to Ask Bjørn Hansen at ask@perl.org | Group listing | About