New gallery example 53 showing subplots and shading

[PaulWessel]

Description of proposed changes

The new example illustrates two useful techniques, one that is new in master:

1. How to use a simple bash loop to create a subplot with potentially a large set of near-identical panels
2. How to use the new coast -E+c|C operator for setting up DCW country clip paths

I dumbed the plots down to using the 6m global grids since any courser makes it look weak. The plot using 2m data looks like below:

Note I also fixed some typos in many of the *.def files hence the many changed files.

[maxrjones]

Nice!

[seisman]

The PS file is so large (> 10 Mb).

[PaulWessel]

I know. And that is after I dumbed it down to 6 minutes. As long as we store PS originals I am not sure what we can do about that - never show anything of high resolution? Thoughts?

[seisman]

Perhaps it's time to use the DVC workflow in the GMT project. The DVC workflow is being used in the PyGMT project. It stores all static images (PNG for PyGMT) on another server, and works pretty well for PyGMT. @meghanrjones Thoughts?

[PaulWessel]

BTW, the PNG version of the above was 11 Mb so I made a JPG (3.7M). Both at 300 dpi default psconvert output.

[maxrjones]

I agree that DVC would be a good solution to the PS size issue @seisman. It would require buy-in from all the core developers since it is one more tool to learn for them and would increase the learning curve a bit for new contributors.

[PaulWessel]

Note that if I try to be space clever and do this in a much more complicated way:

gmt grdcut @earth_relief_06m -R-1500/1500/-1500/1500+uk -JA${lon}/${lat}/6c -Gz.grd
gmt grdgradient z.grd -A-45 -Nt1 -Gint.grd
gmt coast -E${iso} -M | gmt grdmask -Rint.grd -N0.5/0/0 -Gambient.grd
gmt grdmath int.grd ambient.grd SUB = final_int.grd
gmt grdimage z.grd -R-1500/1500/-1500/1500+uk -JA${lon}/${lat}/? -Ifinal_int.grd

Then it takes way (10x) longer (due to the grdmask step) and bud does make the PS about 6 Mb (due to a single rather than two grdimage calls). I think we don't want to make things complicated when the elegant and faster solution is so much better.

[joa-quim]

You know that in my opinion the GMT repo is already too huge due to PSs ...

[PaulWessel]

@meghanrjones, I got an email from git about the DISABLE_TEST suggestions but when I click and get here I do not see anything?

[seisman]

I think we should also remove the ex53.ps file because it's not used in the tests (GMT_DISABLE_TEST) or the documentation (currently we include a static image directly).

[maxrjones]

I think we should also remove the ex53.ps file because it's not used in the tests (GMT_DISABLE_TEST) or the documentation (currently we include a static image directly).

Yes, I think this is the best intermediate solution. But I did not suggest the proper way to include the static image, so some revisions are still needed in addition to removing the ps file.

Also the tests need to be instructed to skip for GMT_DISABLE_TEST. This is the revised version that Paul suggested adding to gmtest.in L19 to skip these tests:

skip_this_test=$(grep GMT_DISABLE_TEST "$script" -c)
if [ $skip_this_test -gt 0 ]; then	# Do not run this script, probably PS is too alrge
		echo "warning: test disabled for script ${script}." >&2
		exit 0
fi

[maxrjones]

I tested that the tests pass and docs build correctly locally with the suggested line changes and the additional changes below.
In doc/rst/source/gallery.rst change

   {% for i in range(1, no_of_examples + 1) %}
   {% set i = '%02d' % i %}
   -  .. figure:: /_images/ex{{i}}.*
         :target: ./gallery/ex{{i}}.html

         :ref:`example_{{i}}`
   {% endfor %}

to

   {% for i in range(1, 53) %}
   {% set i = '%02d' % i %}
   -  .. figure:: /_images/ex{{i}}.*
         :target: ./gallery/ex{{i}}.html

         :ref:`example_{{i}}`
   {% endfor %}

   - .. figure:: https://user-images.githubusercontent.com/14077947/123172626-62ca6880-d44b-11eb-8d91-21e448930460.png
         :target: ./gallery/ex53.html

         :ref:`example_53`

• Add GMT_DISABLE_TEST lines to gmtest.in
• remove doc/examples/ex53/ex53.ps

[PaulWessel]

I see a black rectangle over the bottom half of the PNG figure in vercel...

[maxrjones]

I see a black rectangle over the bottom half of the PNG figure in vercel...

It looks OK for me.

[PaulWessel]

OK, then. Shall we squash and merge?

[seisman]

Don't forget to remove the huge PS file!

[PaulWessel]

Squash and merge when you feel ready.