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+import matplotlib.pyplot as plt
+import numpy as np
+import sklearn
+import sklearn.datasets
+import sklearn.linear_model
+
+def plot_decision_boundary(model, X, y):
+ # Set min and max values and give it some padding
+ x_min, x_max = X[0, :].min() - 1, X[0, :].max() + 1
+ y_min, y_max = X[1, :].min() - 1, X[1, :].max() + 1
+ h = 0.01
+ # Generate a grid of points with distance h between them
+ xx, yy = np.meshgrid(np.arange(x_min, x_max, h), np.arange(y_min, y_max, h))
+ # Predict the function value for the whole grid
+ Z = model(np.c_[xx.ravel(), yy.ravel()])
+ Z = Z.reshape(xx.shape)
+ # Plot the contour and training examples
+ plt.contourf(xx, yy, Z, cmap=plt.cm.Spectral)
+ plt.ylabel('x2')
+ plt.xlabel('x1')
+ plt.scatter(X[0, :], X[1, :], c=y, cmap=plt.cm.Spectral)
+
+
+def sigmoid(x):
+ """
+ Compute the sigmoid of x
+
+ Arguments:
+ x -- A scalar or numpy array of any size.
+
+ Return:
+ s -- sigmoid(x)
+ """
+ s = 1/(1+np.exp(-x))
+ return s
+
+def load_planar_dataset():
+ np.random.seed(1)
+ m = 400 # number of examples
+ N = int(m/2) # number of points per class
+ D = 2 # dimensionality
+ X = np.zeros((m,D)) # data matrix where each row is a single example
+ Y = np.zeros((m,1), dtype='uint8') # labels vector (0 for red, 1 for blue)
+ a = 4 # maximum ray of the flower
+
+ for j in range(2):
+ ix = range(N*j,N*(j+1))
+ t = np.linspace(j*3.12,(j+1)*3.12,N) + np.random.randn(N)*0.2 # theta
+ r = a*np.sin(4*t) + np.random.randn(N)*0.2 # radius
+ X[ix] = np.c_[r*np.sin(t), r*np.cos(t)]
+ Y[ix] = j
+
+ X = X.T
+ Y = Y.T
+
+ return X, Y
+
+def load_extra_datasets():
+ N = 200
+ noisy_circles = sklearn.datasets.make_circles(n_samples=N, factor=.5, noise=.3)
+ noisy_moons = sklearn.datasets.make_moons(n_samples=N, noise=.2)
+ blobs = sklearn.datasets.make_blobs(n_samples=N, random_state=5, n_features=2, centers=6)
+ gaussian_quantiles = sklearn.datasets.make_gaussian_quantiles(mean=None, cov=0.5, n_samples=N, n_features=2, n_classes=2, shuffle=True, random_state=None)
+ no_structure = np.random.rand(N, 2), np.random.rand(N, 2)
+
+ return noisy_circles, noisy_moons, blobs, gaussian_quantiles, no_structure