From 8b8907a6df84e3a95c4ab1b809eec402e80c6fcf Mon Sep 17 00:00:00 2001
From: Tony607 <Tony607@users.noreply.github.com>
Date: Mon, 11 Nov 2019 18:01:42 +0800
Subject: [PATCH] add losses.py

---
 losses.py | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 losses.py

diff --git a/losses.py b/losses.py
new file mode 100644
index 0000000..e575fab
--- /dev/null
+++ b/losses.py
@@ -0,0 +1,68 @@
+from tensorflow.keras.losses import binary_crossentropy
+import tensorflow.keras.backend as K
+import tensorflow as tf 
+
+epsilon = 1e-5
+smooth = 1
+
+def dsc(y_true, y_pred):
+    smooth = 1.
+    y_true_f = K.flatten(y_true)
+    y_pred_f = K.flatten(y_pred)
+    intersection = K.sum(y_true_f * y_pred_f)
+    score = (2. * intersection + smooth) / (K.sum(y_true_f) + K.sum(y_pred_f) + smooth)
+    return score
+
+def dice_loss(y_true, y_pred):
+    loss = 1 - dsc(y_true, y_pred)
+    return loss
+
+def bce_dice_loss(y_true, y_pred):
+    loss = binary_crossentropy(y_true, y_pred) + dice_loss(y_true, y_pred)
+    return loss
+
+def confusion(y_true, y_pred):
+    smooth=1
+    y_pred_pos = K.clip(y_pred, 0, 1)
+    y_pred_neg = 1 - y_pred_pos
+    y_pos = K.clip(y_true, 0, 1)
+    y_neg = 1 - y_pos
+    tp = K.sum(y_pos * y_pred_pos)
+    fp = K.sum(y_neg * y_pred_pos)
+    fn = K.sum(y_pos * y_pred_neg) 
+    prec = (tp + smooth)/(tp+fp+smooth)
+    recall = (tp+smooth)/(tp+fn+smooth)
+    return prec, recall
+
+def tp(y_true, y_pred):
+    smooth = 1
+    y_pred_pos = K.round(K.clip(y_pred, 0, 1))
+    y_pos = K.round(K.clip(y_true, 0, 1))
+    tp = (K.sum(y_pos * y_pred_pos) + smooth)/ (K.sum(y_pos) + smooth) 
+    return tp 
+
+def tn(y_true, y_pred):
+    smooth = 1
+    y_pred_pos = K.round(K.clip(y_pred, 0, 1))
+    y_pred_neg = 1 - y_pred_pos
+    y_pos = K.round(K.clip(y_true, 0, 1))
+    y_neg = 1 - y_pos 
+    tn = (K.sum(y_neg * y_pred_neg) + smooth) / (K.sum(y_neg) + smooth )
+    return tn 
+
+def tversky(y_true, y_pred):
+    y_true_pos = K.flatten(y_true)
+    y_pred_pos = K.flatten(y_pred)
+    true_pos = K.sum(y_true_pos * y_pred_pos)
+    false_neg = K.sum(y_true_pos * (1-y_pred_pos))
+    false_pos = K.sum((1-y_true_pos)*y_pred_pos)
+    alpha = 0.7
+    return (true_pos + smooth)/(true_pos + alpha*false_neg + (1-alpha)*false_pos + smooth)
+
+def tversky_loss(y_true, y_pred):
+    return 1 - tversky(y_true,y_pred)
+
+def focal_tversky(y_true,y_pred):
+    pt_1 = tversky(y_true, y_pred)
+    gamma = 0.75
+    return K.pow((1-pt_1), gamma)