251 lines
10 KiB
Python
251 lines
10 KiB
Python
# Copyright (c) OpenMMLab. All rights reserved.
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from collections import OrderedDict
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from typing import Dict, List, Optional, Sequence
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import numpy as np
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import torch
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from mmengine.evaluator import BaseMetric
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from mmengine.logging import MMLogger, print_log
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from prettytable import PrettyTable
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from mmseg.registry import METRICS
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@METRICS.register_module()
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class IoUMetric(BaseMetric):
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"""IoU evaluation metric.
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Args:
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ignore_index (int): Index that will be ignored in evaluation.
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Default: 255.
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iou_metrics (list[str] | str): Metrics to be calculated, the options
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includes 'mIoU', 'mDice' and 'mFscore'.
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nan_to_num (int, optional): If specified, NaN values will be replaced
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by the numbers defined by the user. Default: None.
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beta (int): Determines the weight of recall in the combined score.
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Default: 1.
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collect_device (str): Device name used for collecting results from
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different ranks during distributed training. Must be 'cpu' or
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'gpu'. Defaults to 'cpu'.
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prefix (str, optional): The prefix that will be added in the metric
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names to disambiguate homonymous metrics of different evaluators.
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If prefix is not provided in the argument, self.default_prefix
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will be used instead. Defaults to None.
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"""
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def __init__(self,
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ignore_index: int = 255,
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iou_metrics: List[str] = ['mIoU'],
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nan_to_num: Optional[int] = None,
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beta: int = 1,
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collect_device: str = 'cpu',
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prefix: Optional[str] = None) -> None:
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super().__init__(collect_device=collect_device, prefix=prefix)
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self.ignore_index = ignore_index
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self.metrics = iou_metrics
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self.nan_to_num = nan_to_num
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self.beta = beta
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def process(self, data_batch: dict, data_samples: Sequence[dict]) -> None:
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"""Process one batch of data and data_samples.
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The processed results should be stored in ``self.results``, which will
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be used to compute the metrics when all batches have been processed.
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Args:
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data_batch (dict): A batch of data from the dataloader.
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data_samples (Sequence[dict]): A batch of outputs from the model.
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"""
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num_classes = len(self.dataset_meta['classes'])
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for data_sample in data_samples:
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pred_label = data_sample['pred_sem_seg']['data'].squeeze()
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label = data_sample['gt_sem_seg']['data'].squeeze().to(pred_label)
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self.results.append(
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self.intersect_and_union(pred_label, label, num_classes,
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self.ignore_index))
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def compute_metrics(self, results: list) -> Dict[str, float]:
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"""Compute the metrics from processed results.
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Args:
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results (list): The processed results of each batch.
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Returns:
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Dict[str, float]: The computed metrics. The keys are the names of
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the metrics, and the values are corresponding results. The key
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mainly includes aAcc, mIoU, mAcc, mDice, mFscore, mPrecision,
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mRecall.
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"""
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logger: MMLogger = MMLogger.get_current_instance()
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# convert list of tuples to tuple of lists, e.g.
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# [(A_1, B_1, C_1, D_1), ..., (A_n, B_n, C_n, D_n)] to
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# ([A_1, ..., A_n], ..., [D_1, ..., D_n])
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results = tuple(zip(*results))
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assert len(results) == 4
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total_area_intersect = sum(results[0])
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total_area_union = sum(results[1])
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total_area_pred_label = sum(results[2])
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total_area_label = sum(results[3])
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ret_metrics = self.total_area_to_metrics(
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total_area_intersect, total_area_union, total_area_pred_label,
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total_area_label, self.metrics, self.nan_to_num, self.beta)
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class_names = self.dataset_meta['classes']
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# summary table
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ret_metrics_summary = OrderedDict({
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ret_metric: np.round(np.nanmean(ret_metric_value) * 100, 2)
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for ret_metric, ret_metric_value in ret_metrics.items()
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})
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metrics = dict()
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for key, val in ret_metrics_summary.items():
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if key == 'aAcc':
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metrics[key] = val
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else:
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metrics['m' + key] = val
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# each class table
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ret_metrics.pop('aAcc', None)
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ret_metrics_class = OrderedDict({
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ret_metric: np.round(ret_metric_value * 100, 2)
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for ret_metric, ret_metric_value in ret_metrics.items()
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})
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ret_metrics_class.update({'Class': class_names})
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ret_metrics_class.move_to_end('Class', last=False)
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class_table_data = PrettyTable()
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for key, val in ret_metrics_class.items():
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class_table_data.add_column(key, val)
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print_log('per class results:', logger)
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print_log('\n' + class_table_data.get_string(), logger=logger)
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return metrics
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@staticmethod
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def intersect_and_union(pred_label: torch.tensor, label: torch.tensor,
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num_classes: int, ignore_index: int):
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"""Calculate Intersection and Union.
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Args:
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pred_label (torch.tensor): Prediction segmentation map
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or predict result filename. The shape is (H, W).
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label (torch.tensor): Ground truth segmentation map
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or label filename. The shape is (H, W).
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num_classes (int): Number of categories.
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ignore_index (int): Index that will be ignored in evaluation.
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Returns:
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torch.Tensor: The intersection of prediction and ground truth
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histogram on all classes.
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torch.Tensor: The union of prediction and ground truth histogram on
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all classes.
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torch.Tensor: The prediction histogram on all classes.
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torch.Tensor: The ground truth histogram on all classes.
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"""
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mask = (label != ignore_index)
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pred_label = pred_label[mask]
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label = label[mask]
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intersect = pred_label[pred_label == label]
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area_intersect = torch.histc(
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intersect.float(), bins=(num_classes), min=0,
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max=num_classes - 1).cpu()
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area_pred_label = torch.histc(
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pred_label.float(), bins=(num_classes), min=0,
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max=num_classes - 1).cpu()
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area_label = torch.histc(
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label.float(), bins=(num_classes), min=0,
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max=num_classes - 1).cpu()
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area_union = area_pred_label + area_label - area_intersect
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return area_intersect, area_union, area_pred_label, area_label
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@staticmethod
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def total_area_to_metrics(total_area_intersect: np.ndarray,
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total_area_union: np.ndarray,
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total_area_pred_label: np.ndarray,
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total_area_label: np.ndarray,
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metrics: List[str] = ['mIoU'],
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nan_to_num: Optional[int] = None,
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beta: int = 1):
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"""Calculate evaluation metrics
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Args:
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total_area_intersect (np.ndarray): The intersection of prediction
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and ground truth histogram on all classes.
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total_area_union (np.ndarray): The union of prediction and ground
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truth histogram on all classes.
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total_area_pred_label (np.ndarray): The prediction histogram on
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all classes.
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total_area_label (np.ndarray): The ground truth histogram on
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all classes.
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metrics (List[str] | str): Metrics to be evaluated, 'mIoU' and
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'mDice'.
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nan_to_num (int, optional): If specified, NaN values will be
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replaced by the numbers defined by the user. Default: None.
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beta (int): Determines the weight of recall in the combined score.
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Default: 1.
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Returns:
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Dict[str, np.ndarray]: per category evaluation metrics,
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shape (num_classes, ).
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"""
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def f_score(precision, recall, beta=1):
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"""calculate the f-score value.
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Args:
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precision (float | torch.Tensor): The precision value.
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recall (float | torch.Tensor): The recall value.
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beta (int): Determines the weight of recall in the combined
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score. Default: 1.
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Returns:
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[torch.tensor]: The f-score value.
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"""
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score = (1 + beta**2) * (precision * recall) / (
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(beta**2 * precision) + recall)
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return score
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if isinstance(metrics, str):
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metrics = [metrics]
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allowed_metrics = ['mIoU', 'mDice', 'mFscore']
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if not set(metrics).issubset(set(allowed_metrics)):
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raise KeyError(f'metrics {metrics} is not supported')
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all_acc = total_area_intersect.sum() / total_area_label.sum()
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ret_metrics = OrderedDict({'aAcc': all_acc})
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for metric in metrics:
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if metric == 'mIoU':
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iou = total_area_intersect / total_area_union
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acc = total_area_intersect / total_area_label
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ret_metrics['IoU'] = iou
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ret_metrics['Acc'] = acc
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elif metric == 'mDice':
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dice = 2 * total_area_intersect / (
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total_area_pred_label + total_area_label)
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acc = total_area_intersect / total_area_label
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ret_metrics['Dice'] = dice
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ret_metrics['Acc'] = acc
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elif metric == 'mFscore':
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precision = total_area_intersect / total_area_pred_label
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recall = total_area_intersect / total_area_label
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f_value = torch.tensor([
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f_score(x[0], x[1], beta) for x in zip(precision, recall)
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])
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ret_metrics['Fscore'] = f_value
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ret_metrics['Precision'] = precision
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ret_metrics['Recall'] = recall
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ret_metrics = {
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metric: value.numpy()
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for metric, value in ret_metrics.items()
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}
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if nan_to_num is not None:
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ret_metrics = OrderedDict({
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metric: np.nan_to_num(metric_value, nan=nan_to_num)
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for metric, metric_value in ret_metrics.items()
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})
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return ret_metrics
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