GROUPWORK_minor corrections

p2/helper.py

 # External
 import torch
-import math
 import matplotlib.pyplot as plt
 
-def generate_disc_set(nb):
+def generate_disc_set(nb, center, radius):
+    # center, convert to tensor for element-wise subtraction
+    center = torch.tensor(center)
+    # (x, y)
     input = torch.empty(nb, 2).uniform_(0, 1)
-    # y^2 = r^2 - x^2
-    target = input.add(-0.5).pow(2).sum(1).sub(1/(2*math.pi)).sign().add(-3).div(2).long()
-    return input, ~target
+    # if (x-c_x)^2 + (y-c_y)^2 - r^2 >= 0 then sign=1, 
+    # if (x-c_x)^2 + (y-c_y)^2 - r^2 < 0 then sign=-1
+    target = input.sub(center).pow(2).sum(1).sub(radius**2).sign().add(1).div(2).long()
+    return input, target
 
 # we will use this for both, at the beginning, and then to visually show the results for the test data
-def plot_figure(input, output, center=(0.5,0.5), radius=1/math.sqrt(2*math.pi)):
+def plot_figure(input, output, center, radius):
     plt.figure()
     plt.scatter(input[:,0], input[:,1], c=output, cmap='RdYlGn')
     circle = plt.Circle(center, radius, color='black', fill=False, lw=5)
     plt.gca().add_patch(circle)
     plt.gca().set_aspect('equal', adjustable='box')
-    plt.show()
+