# -*- coding: utf-8 -*-
"""Methods for loading and visualizion of shapefiles.
Created on Wed May 17 10:26:10 2017
@author: elena
"""
import fiona
from descartes.patch import PolygonPatch
from shapely.geometry import MultiPolygon, mapping, shape
# visualization
def plot_coords(ax, ob):
x, y = ob.xy
ax.plot(x, y, 'o', color='#999999', zorder=1)
[docs]def show_multipolygon(multipolygon, axis, show_coords, extent, color, alpha,
title):
"""Visualize multipolygon in plot."""
for polygon in multipolygon:
if show_coords:
plot_coords(axis, polygon.exterior)
patch = PolygonPatch(
polygon, facecolor=color, edgecolor=color, alpha=alpha, zorder=2)
axis.add_patch(patch)
xmin, ymin, xmax, ymax = extent
xrange = [xmin, xmax]
yrange = [ymin, ymax]
axis.set_xlim(*xrange)
# axis.set_xticks(range(*xrange))
axis.set_ylim(*yrange)
# axis.set_yticks(range(*yrange))
axis.set_aspect(1)
axis.set_title(title)
return axis
[docs]def load_shapefile2multipolygon(filename):
"""Load a shapefile as a MultiPolygon."""
with fiona.open(filename) as file:
multipolygon = MultiPolygon(shape(p['geometry']) for p in file)
bounds = file.bounds
return multipolygon, bounds
[docs]def save_multipolygon2shapefile(multipolygon, shapefilename):
"""Save a MultiPolygon to a shapefile."""
# define the schema
schema = {
'geometry': 'Polygon',
'properties': {
'id': 'int'
},
}
# write to a shapefile
with fiona.open(shapefilename, 'w', 'ESRI Shapefile', schema) as file:
for i, poly in enumerate(multipolygon, start=1):
file.write({
'geometry': mapping(poly),
'properties': {
'id': i
},
})