Re: geographic plotting

[Manfred S. <man...@gm...>]

Am 04.03.20 um 16:07 schrieb Allin Cottrell:
> On Wed, 4 Mar 2020, Manfred Schwarb wrote:
>
>>> This may be putting the cart before the horse, but...
>>> Do you think it would be helpful to teach gnuplot to read shape files?
>>> I imagine it would be possible to test for the presence of shapelib.so
>>> and provide a binary input mode:
>>>
>>>    splot <data> binary filetype=shapelib  with polygons
>>>
>>> I have never worked with this libary so I don't know if it is organized
>>> in such a way that this would be possible.
>>
>> I do it using the gdal software and some shell magic:
>>   # ogr2ogr -f "GMT" gaga.gmt gaga.shp
>>   # grep -v "^#" gaga.gmt | sed 's/>//' > gaga.txt
>
> That's also the approach taken by Bob Mesibov at
> https://www.datafix.com.au/BASHing/2018-10-31.html
>

Well, you don't need 2 blank lines for separation, a single blank line is enough.

More to the topic, I think the shape format is proprietary, complicated, spread over
multiple files, limited (number of fields, length of field names, file size,...),
so in one word: "legacy".
So I don't think it is an appropriate format for interfacing with gnuplot.
I made positive experiences with GeoJSON, it is a simple, very versatile format,
and I think most GIS programs can read and write this format, so why not
use some geojson routine and put it into gnuplot?

Cheers,
Manfred


> I'm hopeful that libshape can do the job without requiring the whole
> of gdal. Libshape was developed by Frank Warmerdam, the guy who
> initially developed gdal, and is used by gdal's OGR library.
>
> Allin Cottrell
>