[plotting] adaptive text coloring

plotting.py

@@ -71,14 +71,16 @@ def figure_confusion_matrix(
     tick_marks = np.arange(len(class_names))
     plt.xticks(tick_marks, class_names, rotation=45)
     plt.yticks(tick_marks, class_names)
-
+    half = (cm.max() + cm.min()) / 2
     for i, j in itertools.product(range(cm.shape[0]), range(cm.shape[1])):
+        fontdict = {"color": "black" if cm[i, j] > half else "white"}
         plt.text(
             j,
             i,
             np.around(cm[i, j], decimals=2),
             horizontalalignment="center",
             size=7,
+            fontdict=fontdict,
         )
 
     plt.ylabel("True label" + " (normed)" * (normalize == "true"))