How to plot adjoining polygons in python given the coordinates of X and Y?

Question

I am new to plotting images in python. Kindly appreciate your help in solving my issue. I have a list which contains dictionary of objects with list of X and Y coordinates of adjoining polygons. I was able to extract X and Y coordinates but when I plot the points using Matplotlib I am not getting proper shape of polygons.

import matplotlib.pyplot as plt

shapes = [{'shape_attributes': {'name': 'polygon', 'all_points_x': [35, 28, 27, 31, 40, 51, 62, 72, 74, 71, 65, 57, 41], 'all_points_y': [74, 55, 32, 16, 4, 6, 12, 35, 56, 74, 83, 86, 81]}, 'region_attributes': {}}, None, {'shape_attributes': {'name': 'polygon', 'all_points_x': [6, 16, 24, 44, 69, 77, 81, 82, 80, 76, 69, 62, 51, 26, 9, 7], 'all_points_y': [85, 77, 78, 83, 92, 100, 106, 115, 118, 120, 122, 125, 126, 112, 98, 92]}, 'region_attributes': {}}]

shapesCordinates = []
for shape in shapes:
    if shape is not None:
        x_cor = shape['shape_attributes']['all_points_x']
        y_cor = shape['shape_attributes']['all_points_y']
        for x, y in zip(x_cor, y_cor):
            shapesCordinates.append((x, y))
print(shapesCordinates)
shapesCordinates.append(shapesCordinates[0])
xs, ys = zip(*shapesCordinates)
plt.figure()
plt.plot(xs,ys) 
plt.show()

https://matplotlib.org/3.1.1/api/_as_gen/matplotlib.patches.Polygon.html — Joe, Apr 06 '20 at 18:24
https://stackoverflow.com/questions/26935701/ploting-filled-polygons-in-python — Joe, Apr 06 '20 at 18:24

JohanC · Accepted Answer · 2020-04-06T18:54:12.713

You might want to draw your polygons one by one. plt.plot will connect all the points in the list to the next, without leaving gaps.

import matplotlib.pyplot as plt

shapes = [{'shape_attributes': {'name': 'polygon', 'all_points_x': [35, 28, 27, 31, 40, 51, 62, 72, 74, 71, 65, 57, 41], 'all_points_y': [74, 55, 32, 16, 4, 6, 12, 35, 56, 74, 83, 86, 81]}, 'region_attributes': {}}, None, {'shape_attributes': {'name': 'polygon', 'all_points_x': [6, 16, 24, 44, 69, 77, 81, 82, 80, 76, 69, 62, 51, 26, 9, 7], 'all_points_y': [85, 77, 78, 83, 92, 100, 106, 115, 118, 120, 122, 125, 126, 112, 98, 92]}, 'region_attributes': {}}]
plt.figure()
for shape in shapes:
    if shape is not None:
        x_cor = shape['shape_attributes']['all_points_x']
        y_cor = shape['shape_attributes']['all_points_y']
        plt.plot(x_cor+x_cor[:1], y_cor+y_cor[:1])
plt.show()

Thank you very much for solving my problem – mohit guru Apr 06 '20 at 19:22 — mohit guru, Apr 06 '20 at 19:22

How to plot adjoining polygons in python given the coordinates of X and Y?

1 Answers1