Add basic bbox helper methods (#3)

Author: vfdev-5

image_dataset_viz/__init__.py

@@ -1,4 +1,63 @@
 
-__version__ = '0.1'
+__version__ = '0.2'
+
+import numpy as np
 
 from image_dataset_viz.dataset_exporter import DatasetExporter, render_datapoint
+
+
+def bbox_to_points(bbox_xyxy):
+    """Helper method to convert bounding box as list/tuple of [x1, y1, x2, y2] into points `ndarray` of shape (N, 2)
+
+    Args:
+        bbox_xyxy (list or tuple): bounding box as list/tuple of [x1, y1, x2, y2]
+
+    Returns:
+        ndarray of points
+
+    """
+    assert isinstance(bbox_xyxy, (list, tuple)) and len(bbox_xyxy) == 4, \
+        "Argument bbox_xyxy should be a list/tuple of [x1, y1, x2, y2]"
+
+    return np.array([
+        [bbox_xyxy[0], bbox_xyxy[1]],
+        [bbox_xyxy[2], bbox_xyxy[1]],
+        [bbox_xyxy[2], bbox_xyxy[3]],
+        [bbox_xyxy[0], bbox_xyxy[3]],
+    ])
+
+
+def xywh_to_xyxy(xywh):
+    """Helper method to transform bounding box of type [x1, y1, width, height] into [x1, y1, x2, y2]
+
+    Args:
+        xywh (list or tuple): bounding box of type [x1, y1, width, height]
+
+    Returns:
+        list [x1, y1, x2, y2]
+
+    """
+    assert isinstance(xywh, (list, tuple)) and len(xywh) == 4, \
+        "Argument xywh should be a list/tuple of [x1, y1, width, height]"
+    x1, y1 = xywh[0], xywh[1]
+    x2 = x1 + max(0, xywh[2] - 1)
+    y2 = y1 + max(0, xywh[3] - 1)
+    return [x1, y1, x2, y2]
+
+
+def xyxy_to_xywh(xyxy):
+    """Helper method to transform bounding box of type [x1, y1, x2, y2] into [x1, y1, width, height]
+
+    Args:
+        xyxy (list or tuple): bounding box of type [x1, y1, x2, y2]
+
+    Returns:
+        list [x1, y1, width, height]
+
+    """
+    assert isinstance(xyxy, (list, tuple)) and len(xyxy) == 4, \
+        "Argument xyxy should be a list/tuple of [x1, y1, x2, y2]"
+    x1, y1 = xyxy[0], xyxy[1]
+    w = xyxy[2] - x1 + 1
+    h = xyxy[3] - y1 + 1
+    return [x1, y1, w, h]

tests/test_image_dataset_viz.py

@@ -0,0 +1,39 @@
+from unittest import TestCase, main
+
+import numpy as np
+
+from image_dataset_viz import bbox_to_points, xywh_to_xyxy, xyxy_to_xywh
+
+
+class TestHelperMethods(TestCase):
+
+    def test_bbox_to_points(self):
+
+        bbox = (10, 12, 34, 45)
+        true_points = np.array([
+            [10, 12],
+            [34, 12],
+            [34, 45],
+            [10, 45]
+        ])
+        points = bbox_to_points(bbox)
+
+        self.assertTrue((true_points == points).all())
+
+    def test_xywh_to_xyxy(self):
+
+        xywh = (10, 12, 34, 45)
+        true_xyxy = [10, 12, 43, 56]
+        xyxy = xywh_to_xyxy(xywh)
+        self.assertEqual(true_xyxy, xyxy)
+
+    def test_xyxy_to_xywh(self):
+
+        xyxy = [10, 12, 43, 56]
+        true_xywh = [10, 12, 34, 45]
+        xywh = xyxy_to_xywh(xyxy)
+        self.assertEqual(true_xywh, xywh)
+
+
+if __name__ == "__main__":
+    main()