Given integer arrays y_true and y_pred with labels in [0, C), return
(cm, macro_f1):
cm is the (C, C) matrix where cm[i, j] counts samples of true class i
predicted as jmacro_f1 is the unweighted mean of per-class F1Input
y_true = [0 1 2 1 0]
y_pred = [0 2 2 1 0]
C = 3
Output
(array([[2, 0, 0],
[0, 1, 1],
[0, 0, 1]]), 0.7777777777777777)