Add spiral dataset

app.py

@@ -88,10 +88,24 @@ def get_varied(n_clusters):
     return normalize(X), labels
 
 
+def get_spiral(n_clusters):
+    # from https://scikit-learn.org/stable/auto_examples/cluster/plot_agglomerative_clustering.html
+    t = 1.5 * np.pi * (1 + 3 * np.random.rand(1, N_SAMPLES))
+    x = t * np.cos(t)
+    y = t * np.sin(t)
+    X = np.concatenate((x, y))
+    X += 0.7 * np.random.randn(2, N_SAMPLES)
+    X = X.T
+
+    labels = np.zeros(N_SAMPLES, dtype=int)
+    return normalize(X), labels
+
+
 DATA_MAPPING = {
     'regular': get_regular,
     'circles': get_circles,
     'moons': get_moons,
+    'spiral': get_spiral,
     'noise': get_noise,
     'anisotropic': get_anisotropic,
     'varied': get_varied,