Add random colors generator for instance plotting (#244)

torch_em/util/util.py

@@ -5,6 +5,8 @@
 import numpy as np
 import torch
 import torch_em
+import matplotlib.pyplot as plt
+from matplotlib import colors
 
 # this is a fairly brittle way to check if a module is compiled.
 # would be good to find a better solution, ideall something like
@@ -246,3 +248,13 @@ def model_is_equal(model1, model2):
         if p1.data.ne(p2.data).sum() > 0:
             return False
     return True
+
+
+
+def get_random_colors(labels):
+    """Function to generate a random color map for a label image
+    """
+    n_labels = len(np.unique(labels)) - 1
+    cmap = [[0, 0, 0]] + np.random.rand(n_labels, 3).tolist()
+    cmap = colors.ListedColormap(cmap)
+    return cmap