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Legends for feature artists #1500

Open

poplarShift wants to merge 12 commits into SciTools:main from poplarShift:legend

poplarShift commented Mar 29, 2020 •

edited

Fixes #334.

Enables legends for FeatureArtists by implementing a legend handler and registering it with matplotlib.

This necessitated factoring out some of the code in the FeatureArtists' draw method to make it accessible to the new HandlerFeature legend handler.

As for tests, I haven't looked into how to test legend handling in matplotlib. Can do that though if you think this PR is useful!

Example:

import matplotlib.pyplot as plt
import cartopy.crs as ccrs
import cartopy.feature as cfeature

ax = plt.axes(projection=ccrs.PlateCarree())
ax.set_extent([80, 170, -45, 30])

states_provinces = cfeature.NaturalEarthFeature(
    category='cultural',
    name='admin_1_states_provinces_lines',
    scale='50m',
    facecolor='none')

land = ax.add_feature(cfeature.LAND, facecolor='wheat', edgecolor='black')
prov = ax.add_feature(states_provinces, edgecolor='gray', ls=':')
plt.legend(handles=[land, prov], labels=['Land', 'Province borders'], loc='lower left')

PS:
cb3de4f draws all legend artists as Polygons, which looks as below, will also respect facecolor options and is much simpler even for LineStrings but may look non-intuitive when facecolor=none.

cb3de4f adds another if/else clause based on facecolor to decide between Rectangle and Line2D for the legend artist, which looks like

PPS:
I have a vague feeling that the legend artists could have been based off of HandlerPathCollection since that is what the FeatureArtist is drawing but I could not find a way to make the right submethods available to the handler since the actual artist is not based off PathCollection.

poplarShift added 4 commits

March 29, 2020 15:53


          factor out stylized paths

2e4e34b


          factor out geometry operations

5fef68d


          simplify passed arguments

b146558


          legend handler for feature artist

5a8bd09

stickler-ci reviewed

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SciTools-assistant added the Blocked: CLA needed label


          stickler-ci

a4abc72

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          more stickler

bd6a831

poplarShift mentioned this pull request

Shape elements cannot display legends holoviz/geoviews#450

Open

poplarShift added 2 commits

March 30, 2020 06:43


          remove comment

049d018


          draw linestrings like polygons

cb3de4f

stickler-ci reviewed

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poplarShift added 4 commits

March 30, 2020 07:01


          decide between Rectangle and Line2D based on facecolor

288a8f0


          allow never as facecolor arg

495d96d


          draw polygons as rectangles regardless

3d58461


          return one artist per path as in path collection handler

0976f53

Author

poplarShift commented Apr 30, 2020 •

edited

I've also submitted the CLA now.

dopplershift added this to the 0.19 milestone

QuLogic modified the milestones: 0.19, 0.20

QuLogic reviewed

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lib/cartopy/mpl/feature_artist.py


		def get_stylised_paths(self, geoms, feature_crs, projection, **kwargs):

Member

QuLogic Sep 8, 2021

Make this private.

lib/cartopy/mpl/feature_artist.py

-                          c.set_clip_path(ax.patch)
-                          c.set_figure(ax.figure)
-                          c.draw(renderer)
+                  def get_geometry(self):

Member

QuLogic Sep 8, 2021

And this too.

lib/cartopy/mpl/feature_artist.py

Comment on lines +232 to +233

		warnings.warn('''Unable to determine extent.
		Defaulting to global.''')

Member

QuLogic Sep 8, 2021

This warning should definitely not have a newline and a bunch of whitespace in it. Use plain strings, not a multiline string.

lib/cartopy/mpl/feature_artist.py

+                      for style in stylised_paths.keys():
+                          style = dict(style)
+                          facecolor = style.get('facecolor', 'none')
+                          if facecolor not in ('none', 'never') or type(geom) is Polygon:

Member

QuLogic Sep 8, 2021

Use isinstance

lib/cartopy/mpl/feature_artist.py

+                                  width=width, height=height,
+                                  **style
+                              )
+                          elif type(geom) in (LineString, LinearRing):

Member

QuLogic Sep 8, 2021

Use isinstance

dopplershift modified the milestones: 0.20, 0.21

QuLogic modified the milestones: 0.21, 0.22

SciTools-assistant removed the Blocked: CLA needed label

dopplershift modified the milestones: 0.22, Next Release

CLAassistant commented Apr 8, 2024

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

QuLogic modified the milestones: Next Release, Next Next Release

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