Print the miou in the segmentation training demo.

demo/semantic_segmentation/train.py

 import paddle
+import numpy as np
 import paddlehub as hub
 from paddlehub.finetune.trainer import Trainer
-
 from paddlehub.datasets import OpticDiscSeg
 from paddlehub.vision.segmentation_transforms import Compose, Resize, Normalize
+from paddlehub.vision.utils import ConfusionMatrix
 
 if __name__ == "__main__":
-    transform = Compose([Resize(target_size=(512, 512)), Normalize()])
-    train_reader = OpticDiscSeg(transform)
+    train_transforms = Compose([Resize(target_size=(512, 512)), Normalize()])
+    eval_transforms = Compose([Normalize()])
+    train_reader = OpticDiscSeg(train_transforms)
+    eval_reader = OpticDiscSeg(eval_transforms, mode='val')
 
     model = hub.Module(name='ocrnet_hrnetw18_voc', num_classes=2)
     scheduler = paddle.optimizer.lr.PolynomialDecay(learning_rate=0.01, decay_steps=1000, power=0.9, end_lr=0.0001)
-    optimizer = paddle.optimizer.Adam(learning_rate=scheduler, parameters=model.parameters())
-    trainer = Trainer(model, optimizer, checkpoint_dir='test_ckpt_img_ocr', use_gpu=True)
-    trainer.train(train_reader, epochs=20, batch_size=4, eval_dataset=train_reader, log_interval=10, save_interval=4)
\ No newline at end of file
+    optimizer = paddle.optimizer.Momentum(learning_rate=scheduler, parameters=model.parameters())
+    trainer = Trainer(model, optimizer, checkpoint_dir='test_ckpt_img_seg', use_gpu=True)
+    trainer.train(train_reader, epochs=10, batch_size=4, log_interval=10, save_interval=4)
+
+    cfm = ConfusionMatrix(eval_reader.num_classes, streaming=True)
+    model.eval()
+    for imgs, labels in eval_reader:
+        imgs = imgs[np.newaxis, :, :, :]
+        preds = model(paddle.to_tensor(imgs))[0]
+        preds = paddle.argmax(preds, axis=1, keepdim=True).numpy()
+        labels = labels[np.newaxis, :, :, :]
+        ignores = labels != eval_reader.ignore_index
+        cfm.calculate(preds, labels, ignores)
+    _, miou = cfm.mean_iou()
+    print('miou: {:.4f}'.format(miou))

paddlehub/vision/utils.py

@@ -21,6 +21,7 @@ import PIL
 import numpy as np
 import matplotlib as plt
 import paddle.nn.functional as F
+from scipy.sparse import csr_matrix
 
 
 def is_image_file(filename: str) -> bool:
@@ -290,3 +291,129 @@ def reverse_transform(pred: paddle.Tensor, ori_shape: List[int], transforms: Lis
         else:
             raise Exception("Unexpected info '{}' in im_info".format(item[0]))
     return pred
+
+
+class ConfusionMatrix(object):
+    """
+    Confusion Matrix for segmentation evaluation.
+
+    Args:
+        num_classes (int): Number of categories of the confusion matrix.
+        streaming (bool): Whether to use streaming mode. If the value is set to True, the data will be
+                          accumulated every time the `calculate` interface is called. Default to False.
+    """
+
+    def __init__(self, num_classes: int, streaming: bool = False):
+        self.confusion_matrix = np.zeros([num_classes, num_classes], dtype='int64')
+        self.num_classes = num_classes
+        self.streaming = streaming
+
+    def calculate(self, pred, label, ignore=None):
+        # If not in streaming mode, clear matrix everytime when call `calculate`
+        if not self.streaming:
+            self.zero_matrix()
+
+        mask = np.array(ignore) == 1
+
+        label = np.asarray(label)[mask]
+        pred = np.asarray(pred)[mask]
+        one = np.ones_like(pred)
+        # Accumuate ([row=label, col=pred], 1) into sparse matrix
+        spm = csr_matrix((one, (label, pred)), shape=(self.num_classes, self.num_classes))
+        spm = spm.todense()
+        self.confusion_matrix += spm
+
+    def zero_matrix(self):
+        """ Clear confusion matrix """
+        self.confusion_matrix = np.zeros([self.num_classes, self.num_classes], dtype='int64')
+
+    def mean_iou(self) -> float:
+        iou_list = []
+        avg_iou = 0
+        # TODO: use numpy sum axis api to simpliy
+        vji = np.zeros(self.num_classes, dtype=int)
+        vij = np.zeros(self.num_classes, dtype=int)
+        for j in range(self.num_classes):
+            v_j = 0
+            for i in range(self.num_classes):
+                v_j += self.confusion_matrix[j][i]
+            vji[j] = v_j
+
+        for i in range(self.num_classes):
+            v_i = 0
+            for j in range(self.num_classes):
+                v_i += self.confusion_matrix[j][i]
+            vij[i] = v_i
+
+        for c in range(self.num_classes):
+            total = vji[c] + vij[c] - self.confusion_matrix[c][c]
+            if total == 0:
+                iou = 0
+            else:
+                iou = float(self.confusion_matrix[c][c]) / total
+            avg_iou += iou
+            iou_list.append(iou)
+        avg_iou = float(avg_iou) / float(self.num_classes)
+        return np.array(iou_list), avg_iou
+
+    def accuracy(self) -> float:
+        total = self.confusion_matrix.sum()
+        total_right = 0
+        for c in range(self.num_classes):
+            total_right += self.confusion_matrix[c][c]
+        if total == 0:
+            avg_acc = 0
+        else:
+            avg_acc = float(total_right) / total
+
+        vij = np.zeros(self.num_classes, dtype=int)
+        for i in range(self.num_classes):
+            v_i = 0
+            for j in range(self.num_classes):
+                v_i += self.confusion_matrix[j][i]
+            vij[i] = v_i
+
+        acc_list = []
+        for c in range(self.num_classes):
+            if vij[c] == 0:
+                acc = 0
+            else:
+                acc = self.confusion_matrix[c][c] / float(vij[c])
+            acc_list.append(acc)
+        return np.array(acc_list), avg_acc
+
+    def kappa(self) -> float:
+        vji = np.zeros(self.num_classes)
+        vij = np.zeros(self.num_classes)
+        for j in range(self.num_classes):
+            v_j = 0
+            for i in range(self.num_classes):
+                v_j += self.confusion_matrix[j][i]
+            vji[j] = v_j
+
+        for i in range(self.num_classes):
+            v_i = 0
+            for j in range(self.num_classes):
+                v_i += self.confusion_matrix[j][i]
+            vij[i] = v_i
+
+        total = self.confusion_matrix.sum()
+
+        # avoid spillovers
+        # TODO: is it reasonable to hard code 10000.0?
+        total = float(total) / 10000.0
+        vji = vji / 10000.0
+        vij = vij / 10000.0
+
+        tp = 0
+        tc = 0
+        for c in range(self.num_classes):
+            tp += vji[c] * vij[c]
+            tc += self.confusion_matrix[c][c]
+
+        tc = tc / 10000.0
+        pe = tp / (total * total)
+        po = tc / total
+
+        kappa = (po - pe) / (1 - pe)
+        return kappa