sklearn.metrics.recall_score
tp / (tp + fn)
Notes
When true positive + false negative == 0, recall returns 0 and raises UndefinedMetricWarning. This behavior can be modified with zero_division.
「TPとFNの和が0のとき、recallは0を返し、UndefinedMetricWarning」を送出
TP = 0 かつ FN = 0、すなわち、正解ラベルに正例がない
Examplesでy_true = [0, 0, 0, 0, 0, 0]
zero_division引数で1に変えられる