from torch import tensor
from torchmetrics.detection.mean_ap import MeanAveragePrecision
preds = [dict(
    boxes=tensor([[258.0, 41.0, 606.0, 285.0]]),
    scores=tensor([0.536]),
    labels=tensor([0]),
)]
target = [dict(
    boxes=tensor([[214.0, 41.0, 562.0, 285.0]]),
    labels=tensor([0]),
)]
metric = MeanAveragePrecision()
metric.update(preds, target)
fig_, ax_ = metric.plot()