Add loss and metrics

src/loss.py

@@ -0,0 +1,17 @@
+import tensorflow as tf
+from metrics import IOU
+
+
+class jaccard_loss(tf.keras.losses.Loss):
+
+    def __init__(self,
+                 smooth=100
+                 ):
+        super().__init__()
+        self.smooth = smooth
+
+    def call(self,
+             y_true,
+             y_pred):
+        iou = IOU(y_true, y_pred, self.smooth)
+        return (1 - iou) * self.smooth

src/metrics.py

@@ -0,0 +1,16 @@
+from keras import backend as K
+
+
+def IOU(y_true,
+        y_pred,
+        smooth=1e-7):
+    '''
+    Taken from https://github.com/keras-team/keras-contrib/blob/master/keras_contrib/losses/jaccard.py
+    '''
+    intersection = K.sum(K.abs(y_true * y_pred), axis=-1)
+    sum_ = K.sum(K.abs(y_true) + K.abs(y_pred), axis=-1)
+
+    jacc = (intersection + smooth) / \
+        (sum_ - intersection + smooth)
+
+    return jacc