make it easier to get colors in a standard format from ClassConfig

These can be passed directly to matplotlib.color.ListedColorMap.

rastervision_core/rastervision/core/data/class_config.py

@@ -2,7 +2,7 @@
 
 from rastervision.pipeline.config import (Config, register_config, ConfigError,
                                           Field, validator)
-from rastervision.core.data.utils import color_to_triple
+from rastervision.core.data.utils import color_to_triple, normalize_color
 
 DEFAULT_NULL_CLASS_NAME = 'null'
 DEFAULT_NULL_CLASS_COLOR = 'black'
@@ -116,3 +116,8 @@ def ensure_null_class(self) -> None:
 
     def __len__(self) -> int:
         return len(self.names)
+
+    @property
+    def color_triples(self) -> List[Tuple[float, float, float]]:
+        color_triples = [normalize_color(c) for c in self.colors]
+        return color_triples

rastervision_core/rastervision/core/data/utils/misc.py

@@ -1,10 +1,11 @@
-from typing import List, Optional, Tuple, Union
+from typing import List, Optional, Sequence, Tuple, Union
 
 import numpy as np
 from PIL import ImageColor
 
 
-def color_to_triple(color: Optional[str] = None) -> Tuple[int, int, int]:
+def color_to_triple(
+        color: Optional[Union[str, Sequence]] = None) -> Tuple[int, int, int]:
     """Given a PIL ImageColor string, return a triple of integers
     representing the red, green, and blue values.
 
@@ -18,12 +19,14 @@ def color_to_triple(color: Optional[str] = None) -> Tuple[int, int, int]:
 
     """
     if color is None:
-        r = np.random.randint(0, 0x100)
-        g = np.random.randint(0, 0x100)
-        b = np.random.randint(0, 0x100)
-        return (r, g, b)
-    else:
+        r, g, b = np.random.randint(0, 256, size=3).tolist()
+        return r, g, b
+    elif isinstance(color, str):
         return ImageColor.getrgb(color)
+    elif isinstance(color, (tuple, list)):
+        return color
+    else:
+        raise TypeError(f'Unsupported type: {type(color)}')
 
 
 def color_to_integer(color: str) -> int:
@@ -44,6 +47,25 @@ def color_to_integer(color: str) -> int:
     return integer
 
 
+def normalize_color(
+        color: Union[str, tuple, list]) -> Tuple[float, float, float]:
+    """Convert color representation to a float 3-tuple with values in [0-1]."""
+    if isinstance(color, str):
+        color = color_to_triple(color)
+
+    if isinstance(color, (tuple, list)):
+        if all(isinstance(c, int) for c in color):
+            return tuple(c / 255. for c in color)
+        elif all(isinstance(c, float) for c in color):
+            return tuple(color)
+        else:
+            raise ValueError('RGB values must be either all ints (0-255) '
+                             'or all floats (0.0-1.0)')
+
+    raise TypeError('Expected color to be a string or tuple or list, '
+                    f'but found {type(color)}.')
+
+
 def rgb_to_int_array(rgb_array):
     r = np.array(rgb_array[:, :, 0], dtype=np.uint32) * (1 << 16)
     g = np.array(rgb_array[:, :, 1], dtype=np.uint32) * (1 << 8)