How to write simple geometric shapes into numpy arrays?

Question

I would like to generate a numpy array of 200x200 elements in size and put into it a circle centered into 100,100 coordinates, radius 80 and stroke width of 3 pixels. How to do this in python 2.7 without involving file operations? Possibly using geometry or imaging libraries to allow generalisation to other shapes.

Answer 1

Hi seeker,

the question has two parts first is the drawing part then the saving part. since the question omits saving to file we need to figure out another way to save

part 1 create the circle using Matplotlib

part 2 save the figure object into a numpy array.

first you will need to import the two python libraries

import matplotlib.pyplot as plt

import numpy as np

for part 1 of the solution use Circle from matplotlib and set the center, radius, and linewidth in the function call and you also need to set your coordinates so you get the correct display 200*200 area. show your drawing to make sure it's correct

fig=plt.figure()

ax=fig.gca(xlim=(0,200),ylim=(0,200))

ax.add_artist(plt.Circle((100,100),radius=80,lw=3,fill=False))

fig.canvas.draw()

look at this example code for saving the canvas into a numpy array and think how would the shape be saved as well!

data = np.frombuffer(fig.canvas.tostring_rgb(), dtype=np.uint8)