Use the Natural Earth datasets rather than geodataset datasets in geopandas gallery examples

[seisman]

Currently, our LineStrings example uses the "eea large_rivers" sample data provided by geodatasets package. The EEA dataset is relatively large (339 KB) and its download link (https://www.eea.europa.eu/data-and-maps/data/wise-large-rivers-and-large-lakes/zipped-shapefile-with-wise-large-rivers-vector-line/zipped-shapefile-with-wise-large-rivers-vector-line/at_download/file) occasionally times out during documentation builds, causing unnecessary failures.

I find that the Natural Earth datasets (https://www.naturalearthdata.com) are better and usually have smaller file sizes. And the mirror URL https://naciscdn.org/naturalearth/ is even more stable.

We can improve both the LineString and choropleth map examples using the Natural Earth data.

[yvonnefroehlich]

Agree that the failing documentation builds are not optimal.

If we do not use the datasets provided by geopandas anymore I think we can remove the optional dependence added in PR #3719. And this issue is superseeding issue #2786.

But we want to keep two seperat examples, or should they be combined into one example (or even tutorial) to show the usage of all three geometries (points, lines, polygons). At least the chorophlet example can be simplied when the high-level method is implemented.

[yvonnefroehlich]

I adjusted the code of our geopandas example used for the paper and could open PRs for updating these two gallery examples; there it's easier to discuss the codes in detail. The maps look promising.

Edit: Codes and images are moved to the PRs

• Polyongs (population, Africa): Example for geopandas polygon geometry: Use the Natural Earth dataset, change to Africa #4228
• Lines (rivers, South America) Example for geopandas line geometry: Use Natural Earth dataset, change to South America #4229
• Points (cities, Europe): Add gallery example for geopandas point geometry (cities in Europe from Natural Earth) #4231

[seisman]

But we want to keep two seperat examples, or should they be combined into one example (or even tutorial) to show the usage of all three geometries (points, lines, polygons). At least the chorophlet example can be simplied when the high-level method is implemented.

I feel it's a good idea to have a tutorial for geopandas support in PyGMT, similar to the example to be included in the paper. It also makes sense to have a separate example for choropleth.