Create ocean bathymetry example #2195
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This time the page built successfully on circleci: bathymetry example |
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Several changes: I realized this fits better under lines_and_polygons, so moved the file there. There is also now more text at top introducing the example, and the colorbar now has an arrow to indicate the depth can go below -10,000 m. Link to current version I should also bring up the earlier commit adding bbox=None to the BasicReader class. This was because the circleci docs builder is not using fiona and passing a bbox as in this example threw an error. Since the two classes are treated interchangeably, I would not expect this to cause an error. Therefore, now the behavior is that passing a bbox will not cause an error but will be silently ignored unless you are using FionaReader. Is this reasonable, or maybe that situation should raise a warning instead noting that the bounding box will not be used? |
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| # Construct colormap: | ||
| # Depth levels in the colorbar are spaced as in the data | ||
| norm = matplotlib.colors.Normalize(vmin=-10000, vmax=0) # in meters |
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Would it be better to quantize this and use BoundaryNorm() here since you have explicit levels?
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Thanks for this comment @greglucas . I have switched it to use BoundaryNorm. This ended up helping better link the data to the colorbar.
| # Add custom colorbar | ||
| axi = fig.add_axes([0.85, 0.1, 0.025, 0.8]) | ||
| ax.add_feature(cfeature.BORDERS, linestyle=':') | ||
| matplotlib.colorbar.ColorbarBase(ax=axi, |
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Can you use fig.colorbar() here instead since I think that is more typical than going for the base classes in an example.
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Thanks for providing those comments. When working through them, I found the color displayed for depth=0 was not matching the colorbar, which is fixed now. Hopefully things are squared away now but please let me know if you see any other issues. |
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Thanks @lgolston! |
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Thanks a lot for all this work, it’s great to see it being finished!
Am 14.07.2023 um 22:03 schrieb Greg Lucas ***@***.***>:
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Rationale
In a previous pull request (#1916) @mattphysics created a notebook for plotting ocean bathymetry using Natural Earth data, but it was not finished. I have here converted it to converted it to a script, reduced the length in some places, and propose adding it to the example gallery.
Implications
The shapereader.natural_earth interface does not work on this particular file, since the .zip contains multiple shapefiles corresponding to different depths. I think it is a nice example using cartopy's shapereader.Reader interface. The axis extent is set to [90, 160, -15, 60] to help speed up the script versus plotting the whole world.
