added checkerboard component

stimuli/components/components.py

@@ -215,3 +215,23 @@ def square_wave(
     ]
     stim[:, index] = low if start == "low" else high
     return (stim, pixels_per_cycle)
+
+
+def checkerboard(
+        ppd=10,
+        board_shape=(8, 8),
+        check_size=1.0,
+        vcheck1=0.0,
+        vcheck2=1.0,
+        ):
+
+    check_size_px = degrees_to_pixels(check_size, ppd)
+    nchecks_height, nchecks_width = board_shape
+
+    img = np.ndarray((nchecks_height, nchecks_width))
+
+    for i, j in np.ndindex((nchecks_height, nchecks_width)):
+        img[i, j] = vcheck1 if i % 2 == j % 2 else vcheck2
+
+    img = img.repeat(check_size_px, axis=0).repeat(check_size_px, axis=1)
+    return img