python - 通过热图填充多边形

Question

我需要使用热图填充我的多边形。对于多边形的来源，我使用 shapefile 。 这是我的代码:

import shapefile
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.patches as patches
import matplotlib.cm as mcm
import matplotlib.image as mpimg 
from matplotlib.patches import Polygon
from matplotlib.collections import PatchCollection
import pylab as plb   


fig     = plt.figure()
ax      = fig.add_subplot(111)
ax.set_frame_on(False)

sf = shapefile.Reader("./data/boundary-polygon")
recs    = sf.records()
shapes  = sf.shapes()
print shapes[1].__dict__
Nshp    = len(shapes)
cns     = []
for nshp in xrange(Nshp):
    cns.append(recs[nshp][1])
cns = np.array(cns)
cm    = mcm.get_cmap('Dark2')
cccol = cm(1.*np.arange(Nshp)/Nshp)
#   facecolor=cccol[nshp,:],

for nshp in xrange(Nshp):
    ptchs   = []
    pts     = np.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]], alpha=1))
    ax.add_collection(PatchCollection(ptchs,facecolors=((1, 1, 1, 1),),alpha=0.1 ,linewidths=1))
ax.set_xlim(54,67)
ax.set_ylim(50,57)

我要改facecolors=((1, 1, 1, 1),)至facecolors=<image_of_my_heat_map> 。任何有关此问题的帮助将不胜感激。

Answer 1

只需将多边形设置为您想要的任何颜色:

ptchs=[]
for pij in xrange(len(prt)):
    ptchs.append(Polygon(pts[par[pij]:par[pij+1]], alpha=1, color=your_color))

然后使用 Warg match_orginal 创建 PatchCollection:

ax.add_collection(PatchCollection(ptchs, match_orginal=True, alpha=0.1 ,linewidths=1))

另请参阅Why is matplotlib.PatchCollection messing with color of the patches?