Added directional_offset_by function to PixCoord

regions/core/pixcoord.py

@@ -247,3 +247,23 @@ def rotate(self, center, angle):
         vec = np.matmul(rotation_matrix, vec)
 
         return self.__class__(center.x + vec[0], center.y + vec[1])
+
+    def directional_offset_by(self, separation, angle):
+        """
+        Computes coordinates at the given offset from this coordinate.
+
+        Parameters
+        ----------
+        separation : `numpy.array`
+            The separation in pixels.
+        angle : `~astropy.coordinates.Angle`
+            The rotation angle.
+
+        Returns
+        -------
+        coord : `PixCoord`
+            The offseted coordinates.
+        """
+        offset_x = self.x + separation * np.cos(angle)
+        offset_y = self.y + separation * np.sin(angle)
+        return PixCoord(offset_x, offset_y)

regions/core/tests/test_pixcoord.py

@@ -286,3 +286,15 @@ def test_pixcoord_subtraction():
 
     with pytest.raises(ValueError):
         point1 - PixCoord([1, 1, 1], [2, 2, 2])
+
+
+def test_pixcoord_offset_scalar():
+    point = PixCoord(3, 4)
+    new_point = point.directional_offset_by(1, 90 * u.deg)
+    assert_allclose(new_point.xy, (3, 5))
+
+
+def test_pixcoord_offset_array():
+    point = PixCoord([3, 3], [4, 4])
+    new_point = point.directional_offset_by(1, 90 * u.deg)
+    assert_allclose(new_point.xy, ([3, 3], [5, 5]))