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# Copyright 2017 The TensorFlow Authors. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# ==============================================================================
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"""Functions for computing metrics like precision, recall, CorLoc and etc."""
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from __future__ import division
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import numpy as np
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def compute_precision_recall(scores, labels, num_gt):
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"""Compute precision and recall.
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Args:
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scores: A float numpy array representing detection score
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labels: A float numpy array representing weighted true/false positive labels
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num_gt: Number of ground truth instances
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Raises:
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ValueError: if the input is not of the correct format
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Returns:
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precision: Fraction of positive instances over detected ones. This value is
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None if no ground truth labels are present.
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recall: Fraction of detected positive instance over all positive instances.
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This value is None if no ground truth labels are present.
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"""
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if not isinstance(labels, np.ndarray) or len(labels.shape) != 1:
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raise ValueError("labels must be single dimension numpy array")
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if labels.dtype != np.float and labels.dtype != np.bool:
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raise ValueError("labels type must be either bool or float")
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if not isinstance(scores, np.ndarray) or len(scores.shape) != 1:
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raise ValueError("scores must be single dimension numpy array")
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if num_gt < np.sum(labels):
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raise ValueError("Number of true positives must be smaller than num_gt.")
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if len(scores) != len(labels):
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raise ValueError("scores and labels must be of the same size.")
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if num_gt == 0:
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return None, None
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sorted_indices = np.argsort(scores)
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sorted_indices = sorted_indices[::-1]
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true_positive_labels = labels[sorted_indices]
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false_positive_labels = (true_positive_labels <= 0).astype(float)
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cum_true_positives = np.cumsum(true_positive_labels)
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cum_false_positives = np.cumsum(false_positive_labels)
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precision = cum_true_positives.astype(float) / (
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cum_true_positives + cum_false_positives)
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recall = cum_true_positives.astype(float) / num_gt
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return precision, recall
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def compute_average_precision(precision, recall):
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"""Compute Average Precision according to the definition in VOCdevkit.
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Precision is modified to ensure that it does not decrease as recall
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decrease.
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Args:
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precision: A float [N, 1] numpy array of precisions
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recall: A float [N, 1] numpy array of recalls
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Raises:
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ValueError: if the input is not of the correct format
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Returns:
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average_precison: The area under the precision recall curve. NaN if
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precision and recall are None.
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"""
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if precision is None:
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if recall is not None:
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raise ValueError("If precision is None, recall must also be None")
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return np.NAN
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if not isinstance(precision, np.ndarray) or not isinstance(
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recall, np.ndarray):
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raise ValueError("precision and recall must be numpy array")
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if precision.dtype != np.float or recall.dtype != np.float:
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raise ValueError("input must be float numpy array.")
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if len(precision) != len(recall):
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raise ValueError("precision and recall must be of the same size.")
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if not precision.size:
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return 0.0
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if np.amin(precision) < 0 or np.amax(precision) > 1:
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raise ValueError("Precision must be in the range of [0, 1].")
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if np.amin(recall) < 0 or np.amax(recall) > 1:
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raise ValueError("recall must be in the range of [0, 1].")
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if not all(recall[i] <= recall[i + 1] for i in range(len(recall) - 1)):
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raise ValueError("recall must be a non-decreasing array")
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recall = np.concatenate([[0], recall, [1]])
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precision = np.concatenate([[0], precision, [0]])
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# Preprocess precision to be a non-decreasing array
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for i in range(len(precision) - 2, -1, -1):
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precision[i] = np.maximum(precision[i], precision[i + 1])
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indices = np.where(recall[1:] != recall[:-1])[0] + 1
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average_precision = np.sum(
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(recall[indices] - recall[indices - 1]) * precision[indices])
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return average_precision
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def compute_cor_loc(num_gt_imgs_per_class,
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num_images_correctly_detected_per_class):
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"""Compute CorLoc according to the definition in the following paper.
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https://www.robots.ox.ac.uk/~vgg/rg/papers/deselaers-eccv10.pdf
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Returns nans if there are no ground truth images for a class.
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Args:
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num_gt_imgs_per_class: 1D array, representing number of images containing
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at least one object instance of a particular class
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num_images_correctly_detected_per_class: 1D array, representing number of
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images that are correctly detected at least one object instance of a
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particular class
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Returns:
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corloc_per_class: A float numpy array represents the corloc score of each
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class
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"""
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return np.where(
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num_gt_imgs_per_class == 0, np.nan,
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num_images_correctly_detected_per_class / num_gt_imgs_per_class)
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def compute_median_rank_at_k(tp_fp_list, k):
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"""Computes MedianRank@k, where k is the top-scoring labels.
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Args:
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tp_fp_list: a list of numpy arrays; each numpy array corresponds to the all
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detection on a single image, where the detections are sorted by score in
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descending order. Further, each numpy array element can have boolean or
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float values. True positive elements have either value >0.0 or True;
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any other value is considered false positive.
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k: number of top-scoring proposals to take.
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Returns:
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median_rank: median rank of all true positive proposals among top k by
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score.
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"""
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ranks = []
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for i in range(len(tp_fp_list)):
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ranks.append(
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np.where(tp_fp_list[i][0:min(k, tp_fp_list[i].shape[0])] > 0)[0])
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concatenated_ranks = np.concatenate(ranks)
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return np.median(concatenated_ranks)
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def compute_recall_at_k(tp_fp_list, num_gt, k):
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"""Computes Recall@k, MedianRank@k, where k is the top-scoring labels.
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Args:
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tp_fp_list: a list of numpy arrays; each numpy array corresponds to the all
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detection on a single image, where the detections are sorted by score in
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descending order. Further, each numpy array element can have boolean or
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float values. True positive elements have either value >0.0 or True;
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any other value is considered false positive.
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num_gt: number of groundtruth anotations.
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k: number of top-scoring proposals to take.
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Returns:
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recall: recall evaluated on the top k by score detections.
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"""
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tp_fp_eval = []
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for i in range(len(tp_fp_list)):
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tp_fp_eval.append(tp_fp_list[i][0:min(k, tp_fp_list[i].shape[0])])
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tp_fp_eval = np.concatenate(tp_fp_eval)
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return np.sum(tp_fp_eval) / num_gt
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