shapefile and matplotlib: plot polygon collection of shapefile coordinates

Question

I'm trying to plot filled polygons of countries on the world map with matplotlib in python.

I've got a shapefile with country boundary coordinates of every country. Now, I want to convert these coordinates (for each country) into a polygon with matplotlib. Without using Basemap. Unfortunately, the parts are crossing or overlapping. Is there a workarund, maybe using the distance from point to point.. or reordering them ?

Answer 1

Ha! I found out, how.. I completely neglected, the sf.shapes[i].parts information! Then it comes down to:

#   -- import --
import shapefile
import matplotlib.pyplot as plt
import matplotlib.patches as patches
from matplotlib.patches import Polygon
from matplotlib.collections import PatchCollection
#   -- input --
sf = shapefile.Reader("./shapefiles/world_countries_boundary_file_world_2002")
recs    = sf.records()
shapes  = sf.shapes()
Nshp    = len(shapes)
cns     = []
for nshp in xrange(Nshp):
    cns.append(recs[nshp][1])
cns = array(cns)
cm    = get_cmap('Dark2')
cccol = cm(1.*arange(Nshp)/Nshp)
#   -- plot --
fig     = plt.figure()
ax      = fig.add_subplot(111)
for nshp in xrange(Nshp):
    ptchs   = []
    pts     = array(shapes[nshp].points)
    prt     = shapes[nshp].parts
    par     = list(prt) + [pts.shape[0]]
    for pij in xrange(len(prt)):
     ptchs.append(Polygon(pts[par[pij]:par[pij+1]]))
    ax.add_collection(PatchCollection(ptchs,facecolor=cccol[nshp,:],edgecolor='k', linewidths=.1))
ax.set_xlim(-180,+180)
ax.set_ylim(-90,90)
fig.savefig('test.png')

Then it will look like this: