def _write_annotations(
self,
centers_and_annot: List[Tuple[Point, Optional[str]]],
collection: mpl_collections.Collection,
ax: plt.Axes,
) -> None:
"""Writes annotations to the center of cells. Internal."""
for (center, annotation), facecolor in zip(centers_and_annot, collection.get_facecolors()):
# Calculate the center of the cell, assuming that it is a square
# centered at (x=col, y=row).
if not annotation:
continue
x, y = center
face_luminance = vis_utils.relative_luminance(facecolor)
text_color = 'black' if face_luminance > 0.4 else 'white'
text_kwargs = dict(color=text_color, ha="center", va="center")
text_kwargs.update(self._config.get('annotation_text_kwargs', {}))
ax.text(x, y, annotation, **text_kwargs)
def relative_luminance(color: np.ndarray) -> float:
return vis_utils.relative_luminance(color)