Wrong point location in inset

[eyalshimony]

Description of the problem

When plotting a point in an inset, it is drawn in the wrong geographic location.

Full code that generated the error

import pygmt

region = [-117.628, -117.478, 35.605, 35.801]
fig = pygmt.Figure()
pygmt.makecpt(
    cmap='etopo1',
    series='0/2800/200',
    continuous=True
)
topo_data = "@earth_relief_01s"
fig.grdimage(
    grid=topo_data,
    region=region,
    projection='M4i',
    shading=True,
    frame=True
)

with fig.inset(position="jTR+w3c", box="+pblack"):
    # Use a plotting function to create a figure inside the inset
    fig.coast(
        region=[-125, -110, 30, 45],
        projection="M3c",
        land="gray",
        borders=[1, 2],
        shorelines="1/thin",
        water="white"
    )
    fig.plot(x=-117.55, y=35.7, size=[0.2], style="c", color="black")
fig.show()

System information

Please paste the output of python -c "import pygmt; pygmt.show_versions()":

PyGMT information:
version: v0.6.0
System information:
python: 3.10.0 (tags/v3.10.0:b494f59, Oct 4 2021, 19:00:18) [MSC v.1929 64 bit (AMD64)]
executable: C:\Users\eyals\AppData\Local\Programs\Python\Python310\python.exe
machine: Windows-10-10.0.19044-SP0
Dependency information:
numpy: 1.21.2
pandas: 1.3.3
xarray: 0.19.0
netCDF4: 1.5.7
packaging: 21.0
ghostscript: 9.54.0
gmt: 6.3.0
GMT library information:
binary dir: C:/Users/eyals/AppData/Local/Programs/Python/Python310
cores: 4
grid layout: rows
library path: c:/programs/gmt6/bin/gmt_w64.dll
padding: 2
plugin dir: c:/programs/gmt6/bin/gmt_plugins
share dir: c:/programs/gmt6/share
version: 6.3.0

[weiji14]

Hi @eyalshimony, thanks for trying PyGMT! So it's a bit unintuitive, but it's best not to set the projection width in the inset plot. Try this instead:

with fig.inset(position="jTR+w3c", box="+pblack"):
    # Use a plotting function to create a figure inside the inset
    fig.coast(
        region=[-125, -110, 30, 45],
        projection="M?c",
        land="gray",
        borders=[1, 2],
        shorelines="1/thin",
        water="white"
    )
    fig.plot(x=-117.55, y=35.7, size=[0.2], style="c", frame="afg", color="black")

Specifically, use projection="M?c" instead of projection="M3c", which means the size is scaled automatically to the inset box. This should produce:

You may need to adjust the width in fig.inset(position="jTR+w3c", ...) to make the box be the correct size.

[eyalshimony]

Thanks for the quick response!

It may be helpful for other users if you'll correct the example in https://www.pygmt.org/v0.3.0/tutorials/inset.html accordingly.

[weiji14]

Thanks for the quick response!

It may be helpful for other users if you'll correct the example in https://www.pygmt.org/v0.3.0/tutorials/inset.html accordingly.

Yes that would be a good idea. Would you like to try making a quick change at https://github.com/GenericMappingTools/pygmt/edit/main/examples/tutorials/advanced/insets.py?

[eyalshimony]

I submitted the change

[eyalshimony]

I am sorry, I checked it and it actually ruins some stuff in the example. Most importantly, the highlighting stops working. I do not know enough about this in order to fix it, so I think it is best be left to the experts.

[michaelgrund]

I submitted the change

Where did you submit it? Just take a look at our contributing guide on how to create a PR for fixing issues 😉.

[weiji14]

I see you've made the change at https://github.com/eyalshimony/pygmt/tree/patch-1. If you click on the 'Contribute' button and then Open Pull Request, we'll be able to see it.

[eyalshimony]

Yes, I understood it afterwards but as I said above changing the projection along your recommendations ruins the highlighting. I have no idea why, so I think it would be better if you'd fix it.

[weiji14]

Hmm yeah, I just tried using M?c for that example but don't understand why the red highlight is incorrect either 😅 You're still welcome to open the Pull Request if you'd like, that way it will be faster for someone to check it and give suggestions on what to do. But I understand if you're short on time.

[seisman]

I'm reopening the issue to track the potential issue in https://github.com/GenericMappingTools/pygmt/blob/main/examples/tutorials/advanced/insets.py