Filling shapefile polygons with a color in matplotlib

Question

I am searching way to fill polygons of a shapefile based on a value. So far from basemap tutorial (http://basemaptutorial.readthedocs.io/en/latest/shapefile.html) i \'ve fou

Answer 1

It seems you want to produce a choropleth plot in basemap.
To this end you need a colormap cmap and a normalization norm in order to map values to colors, cmap(norm(val)). For each shape one may than set the Polygon's color to the respective color from the dictionary, in this case cmap(norm(dict1[info['ID_2']])).

Inside the PatchCollection the match_original=True needs to be set to keep the colors from the original polygons.

At the end it may be useful to produce a colormap from the colormap and the normalization.

import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap
from matplotlib.patches import Polygon
from matplotlib.collections import PatchCollection
import numpy as np

fig= plt.figure()
ax= fig.add_subplot(111)
m=Basemap(projection='cyl',llcrnrlat=34.5,llcrnrlon=19,
                           urcrnrlat=42,urcrnrlon=28.5,resolution='h')
m.drawmapboundary(fill_color='aqua')
m.fillcontinents(color='w',lake_color='aqua')
m.drawcoastlines()
m.readshapefile('data/nomoi/nomoi','nomoi')

dict1={14464: 1.16, 14465: 1.35, 14466: 1.28, 14467: 1.69, 14468: 1.81, 14418: 1.38}
colvals = dict1.values()

cmap=plt.cm.RdYlBu
norm=plt.Normalize(min(colvals),max(colvals))

patches   = []

for info, shape in zip(m.nomoi_info, m.nomoi):
    if info['ID_2'] in list(dict1.keys()):
        color=cmap(norm(dict1[info['ID_2']]))
        patches.append( Polygon(np.array(shape), True, color=color) )

pc = PatchCollection(patches, match_original=True, edgecolor='k', linewidths=1., zorder=2)
ax.add_collection(pc)

#colorbar
sm = plt.cm.ScalarMappable(cmap=cmap, norm=norm)
sm.set_array(colvals)
fig.colorbar(sm, ax=ax)

plt.show()