#!/usr/bin/env python # -*- coding: utf-8 -*- from matplotlib import pyplot from descartes import PolygonPatch from shapely.ops import polygonize from shapely.geometry import Polygon, LineString, Point from utils import SIZE, BLUE from utils import plot_coords_line from utils import plot_line from utils import set_plot_bounds # setup matplotlib figure that will display the results fig = pyplot.figure(1, figsize=SIZE, dpi=90, facecolor="white") # add a little more space around subplots fig.subplots_adjust(hspace=.5) # ################################### # first plot # display sample line and circle # ################################### # first figure upper left drawing # 121 represents the number_rows, num_cols, subplot number ax = fig.add_subplot(121) # our demonstration geometries to see the details line = LineString([(0, 1), (3, 1), (0, 0)]) polygon = Polygon(Point(1.5, 1).buffer(1)) # use of descartes to create polygon in matplotlib patch1 = PolygonPatch(polygon, fc=BLUE, ec=BLUE, alpha=0.5, zorder=1) # add circle to axis in figure ax.add_patch(patch1) # add line using our function above plot_line(ax, line) # draw the line nodes using our function plot_coords_line(ax, line) # subplot title text ax.set_title('Input line and circle') # define axis ranges as list [x-min, x-max] # added 1.5 units around object so not touching the sides x_range = [polygon.bounds[0] - 1.5, polygon.bounds[2] + 1.5] # y-range [y-min, y-max] y_range = [polygon.bounds[1] - 1.0, polygon.bounds[3] + 1.0] # set the x and y axis limits ax.set_xlim(x_range) ax.set_ylim(y_range) # assing the aspect ratio ax.set_aspect(1) ##################################### # second plot # display sample intersection # ################################### ax = fig.add_subplot(122) # convert circle polygon to linestring of circle boundary cirle_as_line = polygon.boundary # combine new boundary lines with the input set of lines result_union_lines = cirle_as_line.union(line) # re-create polygons from unioned lines new_polygons = polygonize(result_union_lines) # stores the final split up polygons new_cut_ply = [] # identify which new polygon we want to keep for poly in new_polygons: # check if new poly is inside original otherwise ignore it if poly.centroid.within(polygon): # center_pt = poly.centroid # ax.plot(center_pt.x, center_pt.y, 'o', color='#999999') print("creating new split polygon") patch3 = PolygonPatch(poly, fc='purple', alpha=0.5, zorder=2) ax.add_patch(patch3) # add only polygons that overlap original for export new_cut_ply.append(poly) else: # draw centroid of new polygon NOT inside original polygon # center_pt = poly.centroid # ax.plot(center_pt.x, center_pt.y, 'o', color='#FF1813') print("This polygon is outside of the input features") # write title of second plot ax.set_title('Line intersects circle') # define the area that plot will fit into x_range = set_plot_bounds(polygon, 1.5)['xrange'] y_range = set_plot_bounds(polygon, 1)['yrange'] ax.set_xlim(*x_range) ax.set_ylim(*y_range) ax.set_aspect(1) pyplot.show()
