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Face_recog/verifacation.py

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+"""Helper for evaluation on the Labeled Faces in the Wild dataset
+"""
+
+# MIT License
+#
+# Copyright (c) 2016 David Sandberg
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+import numpy as np
+from sklearn.model_selection import KFold
+from sklearn.decomposition import PCA
+import sklearn
+from scipy import interpolate
+import datetime
+import mxnet as mx
+
+def calculate_roc(thresholds, embeddings1, embeddings2, actual_issame, nrof_folds=10, pca=0):
+    assert (embeddings1.shape[0] == embeddings2.shape[0])
+    assert (embeddings1.shape[1] == embeddings2.shape[1])
+    nrof_pairs = min(len(actual_issame), embeddings1.shape[0])
+    nrof_thresholds = len(thresholds)
+    k_fold = KFold(n_splits=nrof_folds, shuffle=False)
+
+    tprs = np.zeros((nrof_folds, nrof_thresholds))
+    fprs = np.zeros((nrof_folds, nrof_thresholds))
+    accuracy = np.zeros((nrof_folds))
+    best_thresholds = np.zeros((nrof_folds))
+    indices = np.arange(nrof_pairs)
+    # print('pca', pca)
+
+    if pca == 0:
+        diff = np.subtract(embeddings1, embeddings2)
+        dist = np.sum(np.square(diff), 1)
+
+    for fold_idx, (train_set, test_set) in enumerate(k_fold.split(indices)):
+        # print('train_set', train_set)
+        # print('test_set', test_set)
+        if pca > 0:
+            print('doing pca on', fold_idx)
+            embed1_train = embeddings1[train_set]
+            embed2_train = embeddings2[train_set]
+            _embed_train = np.concatenate((embed1_train, embed2_train), axis=0)
+            # print(_embed_train.shape)
+            pca_model = PCA(n_components=pca)
+            pca_model.fit(_embed_train)
+            embed1 = pca_model.transform(embeddings1)
+            embed2 = pca_model.transform(embeddings2)
+            embed1 = sklearn.preprocessing.normalize(embed1)
+            embed2 = sklearn.preprocessing.normalize(embed2)
+            # print(embed1.shape, embed2.shape)
+            diff = np.subtract(embed1, embed2)
+            dist = np.sum(np.square(diff), 1)
+
+        # Find the best threshold for the fold
+        acc_train = np.zeros((nrof_thresholds))
+        for threshold_idx, threshold in enumerate(thresholds):
+            _, _, acc_train[threshold_idx] = calculate_accuracy(threshold, dist[train_set], actual_issame[train_set])
+        best_threshold_index = np.argmax(acc_train)
+#         print('best_threshold_index', best_threshold_index, acc_train[best_threshold_index])
+        best_thresholds[fold_idx] = thresholds[best_threshold_index]
+        for threshold_idx, threshold in enumerate(thresholds):
+            tprs[fold_idx, threshold_idx], fprs[fold_idx, threshold_idx], _ = calculate_accuracy(threshold,
+                                                                                                 dist[test_set],
+                                                                                                 actual_issame[
+                                                                                                     test_set])
+        _, _, accuracy[fold_idx] = calculate_accuracy(thresholds[best_threshold_index], dist[test_set],
+                                                      actual_issame[test_set])
+
+    tpr = np.mean(tprs, 0)
+    fpr = np.mean(fprs, 0)
+    return tpr, fpr, accuracy, best_thresholds
+
+
+def calculate_accuracy(threshold, dist, actual_issame):
+    predict_issame = np.less(dist, threshold)
+    tp = np.sum(np.logical_and(predict_issame, actual_issame))
+    fp = np.sum(np.logical_and(predict_issame, np.logical_not(actual_issame)))
+    tn = np.sum(np.logical_and(np.logical_not(predict_issame), np.logical_not(actual_issame)))
+    fn = np.sum(np.logical_and(np.logical_not(predict_issame), actual_issame))
+
+    tpr = 0 if (tp + fn == 0) else float(tp) / float(tp + fn)
+    fpr = 0 if (fp + tn == 0) else float(fp) / float(fp + tn)
+    acc = float(tp + tn) / dist.size
+    return tpr, fpr, acc
+
+
+def calculate_val(thresholds, embeddings1, embeddings2, actual_issame, far_target, nrof_folds=10):
+    '''
+    Copy from [insightface](https://github.com/deepinsight/insightface)
+    :param thresholds:
+    :param embeddings1:
+    :param embeddings2:
+    :param actual_issame:
+    :param far_target:
+    :param nrof_folds:
+    :return:
+    '''
+    assert (embeddings1.shape[0] == embeddings2.shape[0])
+    assert (embeddings1.shape[1] == embeddings2.shape[1])
+    nrof_pairs = min(len(actual_issame), embeddings1.shape[0])
+    nrof_thresholds = len(thresholds)
+    k_fold = KFold(n_splits=nrof_folds, shuffle=False)
+
+    val = np.zeros(nrof_folds)
+    far = np.zeros(nrof_folds)
+
+    diff = np.subtract(embeddings1, embeddings2)
+    dist = np.sum(np.square(diff), 1)
+    indices = np.arange(nrof_pairs)
+
+    for fold_idx, (train_set, test_set) in enumerate(k_fold.split(indices)):
+
+        # Find the threshold that gives FAR = far_target
+        far_train = np.zeros(nrof_thresholds)
+        for threshold_idx, threshold in enumerate(thresholds):
+            _, far_train[threshold_idx] = calculate_val_far(threshold, dist[train_set], actual_issame[train_set])
+        if np.max(far_train) >= far_target:
+            f = interpolate.interp1d(far_train, thresholds, kind='slinear')
+            threshold = f(far_target)
+        else:
+            threshold = 0.0
+
+        val[fold_idx], far[fold_idx] = calculate_val_far(threshold, dist[test_set], actual_issame[test_set])
+
+    val_mean = np.mean(val)
+    far_mean = np.mean(far)
+    val_std = np.std(val)
+    return val_mean, val_std, far_mean
+
+
+def calculate_val_far(threshold, dist, actual_issame):
+    predict_issame = np.less(dist, threshold)
+    true_accept = np.sum(np.logical_and(predict_issame, actual_issame))
+    false_accept = np.sum(np.logical_and(predict_issame, np.logical_not(actual_issame)))
+    n_same = np.sum(actual_issame)
+    n_diff = np.sum(np.logical_not(actual_issame))
+    val = float(true_accept) / float(n_same)
+    far = float(false_accept) / float(n_diff)
+    return val, far
+
+
+def evaluate(embeddings, actual_issame, nrof_folds=10, pca=0):
+    # Calculate evaluation metrics
+    thresholds = np.arange(0, 4, 0.01)
+    embeddings1 = embeddings[0::2]
+    embeddings2 = embeddings[1::2]
+    tpr, fpr, accuracy, best_thresholds = calculate_roc(thresholds, embeddings1, embeddings2,
+                                       np.asarray(actual_issame), nrof_folds=nrof_folds, pca=pca)
+#     thresholds = np.arange(0, 4, 0.001)
+#     val, val_std, far = calculate_val(thresholds, embeddings1, embeddings2,
+#                                       np.asarray(actual_issame), 1e-3, nrof_folds=nrof_folds)
+#     return tpr, fpr, accuracy, best_thresholds, val, val_std, far
+    return tpr, fpr, accuracy, best_thresholds