title: create legend for markercolor and size
body: <p>I've created the following figure:</p>
  <p><a href="https://i.stack.imgur.com/ZiCZh.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ZiCZh.png" alt="enter image description here" /></a></p>
  <p>With following code:</p>
  <pre><code>matplotlib.rcParams.update({'font.size': 10})
  
  fig = plt.figure(figsize=(16, 9), dpi=300, facecolor='white')
  ax = plt.subplot(111, projection=ccrs.PlateCarree())
  ax.set_extent(extent)
  
  # cartopy layers
  country_10m = cartopy.feature.NaturalEarthFeature('cultural', 'admin_0_countries', '10m')
  ax.add_feature(country_10m, edgecolor='w', linewidth=0.75, facecolor='#EEEFEE', label='country border')
  ax.coastlines(resolution='10m', color='#EEEFEE', linewidth=0.75)
  ax.imshow(np.tile(np.array([[[191, 210, 217]]], dtype=np.uint8), [2, 2, 1]), origin='lower', transform=cartopy.crs.PlateCarree(), extent=extent)
  
  ax.scatter(gdf_ldb.x, gdf_ldb.y, c= gdf_ldb.Color, s= gdf_ldb.Markersize, zorder=30) 
  # ax.scatter(gdf_ports_filt.longitude, gdf_ports_filt.latitude, s= 10, color= 'k', zorder= 30)
  
  ax.gridlines(crs=ccrs.PlateCarree(), draw_labels=True, linewidth=1, color='gray', alpha=0.5, linestyle='-')
  ax.text(-0.08, 0.5, 'latitude [°]', va='bottom', ha='center',rotation='vertical', rotation_mode='anchor',transform=ax.transAxes);
  ax.text(0.5, -0.09, 'longitude [°]', va='bottom', ha='center', rotation='horizontal', rotation_mode='anchor', transform=ax.transAxes);
  </code></pre>
  <p>How do I create a legend for the markersize as well for the color, so like this:</p>
  <p><a href="https://i.stack.imgur.com/gHrTl.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/gHrTl.png" alt="enter image description here" /></a></p>
  <p>With x, x1, and x2 representing the values of the markersizes.</p>
  <p>gdf_ldb looks like:</p>
  <pre><code>    x   y   Type    Color   Markersize  geometry
  prograding_feature_polygon_29   12.857701   56.648035   Updrift grey    3.0 POINT (12.85770 56.64804)
  prograding_feature_polygon_57   17.781445   54.808079   Updrift grey    3.0 POINT (17.78144 54.80808)
  prograding_feature_polygon_58   17.438390   54.754518   Updrift grey    3.0 POINT (17.43839 54.75452)
  prograding_feature_polygon_63   4.708077    52.880322   Updrift grey    3.0 POINT (4.70808 52.88032)
  prograding_feature_polygon_72   3.953364    51.842299   Updrift grey    3.0 POINT (3.95336 51.84230)
  ... ... ... ... ... ... ...
  retreating_feature_polygon_2018 -10.148432  53.415224   Double Updrift  grey    3.0 POINT (-10.14843 53.41522)
  retreating_feature_polygon_2019 -9.954510   54.197329   Double Updrift  grey    3.0 POINT (-9.95451 54.19733)
  retreating_feature_polygon_2119 15.095564   37.389535   Double Updrift  grey    3.0 POINT (15.09556 37.38953)
  retreating_feature_polygon_2120 14.317893   37.025026   Double Updrift  grey    3.0 POINT (14.31789 37.02503)
  retreating_feature_polygon_2121 13.952111   37.101009   Updrift grey    3.0 POINT (13.95211 37.10101)
  
  
  
  Thanks in advance,
  
  Dante
  </code></pre>