Uniform color distribution

Fixes #11

---

For more details, open the [Copilot Workspace session](https://copilot-workspace.githubnext.com/debrief/ExtractionHighlighter/issues/11?shareId=XXXX-XXXX-XXXX-XXXX).

data_highlight/support/color_picker.py

@@ -1,52 +1,53 @@
-import random
-import colorsys
-
-
-def color_for(hash_code, color_dict):
-    """
-    Get a color for a specific 'hash code' by either taking one we've already recorded for this hash code,
-    or generating a new random one.
-    """
-    # do we have it already?
-    if hash_code in color_dict:
-        # yes, job done
-        return color_dict[hash_code]
-    else:
-        # no, generate one
-        hue = random.random()
-        sat = 0.9 + random.random() * 0.1
-        rgb = colorsys.hsv_to_rgb(hue, sat, 0.9)
-        r = int(rgb[0] * 255)
-        g = int(rgb[1] * 255)
-        b = int(rgb[2] * 255)
-        new_col = (r, g, b)
-        # store the new color
-        color_dict[hash_code] = new_col
-        return new_col
-
-
-def hex_color_for(rgb):
-    """
-    Convert a 3-element rgb structure to a HTML color definition
-    """
-    opacity_shade = 0.3
-    return "rgba(%d,%d,%d,%f)" % (rgb[0], rgb[1], rgb[2], opacity_shade)
-
-
-def mean_color_for(color_arr):
-    """
-    find the mean of the provided colors
-
-    Args:
-        color_arr: three-element list of R, G and B components of color
-    """
-    r = 0
-    g = 0
-    b = 0
-    for color in color_arr:
-        r += color[0]
-        g += color[1]
-        b += color[2]
-
-    arr_len = len(color_arr)
-    return int(r / arr_len), int(g / arr_len), int(b / arr_len)
+import random
+import colorsys
+
+
+def color_for(hash_code, color_dict, total_colors):
+    """
+    Get a color for a specific 'hash code' by either taking one we've already recorded for this hash code,
+    or generating a new one at regular intervals in the HSV color model.
+    """
+    # do we have it already?
+    if hash_code in color_dict:
+        # yes, job done
+        return color_dict[hash_code]
+    else:
+        # no, generate one
+        hue = (len(color_dict) / total_colors) % 1.0
+        sat = 0.9
+        val = 0.9
+        rgb = colorsys.hsv_to_rgb(hue, sat, val)
+        r = int(rgb[0] * 255)
+        g = int(rgb[1] * 255)
+        b = int(rgb[2] * 255)
+        new_col = (r, g, b)
+        # store the new color
+        color_dict[hash_code] = new_col
+        return new_col
+
+
+def hex_color_for(rgb):
+    """
+    Convert a 3-element rgb structure to a HTML color definition
+    """
+    opacity_shade = 0.3
+    return "rgba(%d,%d,%d,%f)" % (rgb[0], rgb[1], rgb[2], opacity_shade)
+
+
+def mean_color_for(color_arr):
+    """
+    find the mean of the provided colors
+
+    Args:
+        color_arr: three-element list of R, G and B components of color
+    """
+    r = 0
+    g = 0
+    b = 0
+    for color in color_arr:
+        r += color[0]
+        g += color[1]
+        b += color[2]
+
+    arr_len = len(color_arr)
+    return int(r / arr_len), int(g / arr_len), int(b / arr_len)

test/test_Colors.py

@@ -1,51 +1,63 @@
-import unittest
-from data_highlight.support.color_picker import color_for, hex_color_for, mean_color_for
-
-
-class ColorTests(unittest.TestCase):
-
-    ############################
-    #### setup and teardown ####
-    ############################
-
-    def setUp(self):
-        pass
-
-    def tearDown(self):
-        pass
-
-    ####################
-    #### file tests ####
-    ####################
-
-    def test_ColorFor(self):
-        color_dict = {}
-        color1 = color_for("aaa", color_dict)
-        assert color1 is not None
-        self.assertEqual(1, len(color_dict))
-
-        color2 = color_for("bbb", color_dict)
-        assert color2 is not None
-        self.assertEqual(2, len(color_dict))
-        self.assertNotEqual(color1, color2)
-
-        color3 = color_for("aaa", color_dict)
-        self.assertEqual(2, len(color_dict), "Should not have created new dict entry")
-        self.assertEqual(color1, color3)
-
-    def test_HexConversion(self):
-        red = (255, 0, 0)
-        self.assertEqual("rgba(255,0,0,0.300000)", hex_color_for(red))
-
-    def test_MeanColor(self):
-        color1 = (100, 50, 200)
-        color2 = (50, 0, 150)
-        color3 = (150, 100, 250)
-
-        self.assertEqual((75, 25, 175), mean_color_for((color1, color2)))
-        self.assertEqual((100, 50, 200), mean_color_for((color3, color2)))
-        self.assertEqual((100, 50, 200), mean_color_for((color1, color2, color3)))
-
-
-if __name__ == "__main__":
-    unittest.main()
+import unittest
+from data_highlight.support.color_picker import color_for, hex_color_for, mean_color_for
+
+
+class ColorTests(unittest.TestCase):
+
+    ############################
+    #### setup and teardown ####
+    ############################
+
+    def setUp(self):
+        pass
+
+    def tearDown(self):
+        pass
+
+    #####################
+    #### color tests ####
+    #####################
+
+    def test_ColorFor(self):
+        color_dict = {}
+        color1 = color_for("aaa", color_dict, 10)
+        assert color1 is not None
+        self.assertEqual(1, len(color_dict))
+
+        color2 = color_for("bbb", color_dict, 10)
+        assert color2 is not None
+        self.assertEqual(2, len(color_dict))
+        self.assertNotEqual(color1, color2)
+
+        color3 = color_for("aaa", color_dict, 10)
+        self.assertEqual(2, len(color_dict), "Should not have created new dict entry")
+        self.assertEqual(color1, color3)
+
+    def test_HexConversion(self):
+        red = (255, 0, 0)
+        self.assertEqual("rgba(255,0,0,0.300000)", hex_color_for(red))
+
+    def test_MeanColor(self):
+        color1 = (100, 50, 200)
+        color2 = (50, 0, 150)
+        color3 = (150, 100, 250)
+
+        self.assertEqual((75, 25, 175), mean_color_for((color1, color2)))
+        self.assertEqual((100, 50, 200), mean_color_for((color3, color2)))
+        self.assertEqual((100, 50, 200), mean_color_for((color1, color2, color3)))
+
+    def test_UniformColorDistribution(self):
+        color_dict = {}
+        total_colors = 10
+        colors = [color_for(str(i), color_dict, total_colors) for i in range(total_colors)]
+        self.assertEqual(total_colors, len(set(colors)), "Colors are not uniformly distributed")
+
+        for i in range(total_colors - 1):
+            color1 = colors[i]
+            color2 = colors[i + 1]
+            contrast = abs(color1[0] - color2[0]) + abs(color1[1] - color2[1]) + abs(color1[2] - color2[2])
+            self.assertGreater(contrast, 50, "Adjacent colors do not have sufficient contrast")
+
+
+if __name__ == "__main__":
+    unittest.main()