import keras.backend as K
smooth = 1.

#dice coefficient
def dice_coef(y_true, y_pred):
    y_true_f = K.flatten(y_true)
    y_pred_f = K.flatten(y_pred)
    intersection = K.sum(y_true_f * y_pred_f)
    return (2. * intersection + smooth) / (K.sum(y_true_f) + K.sum(y_pred_f) + smooth)
#dice loss 
def dice_coef_loss(y_true, y_pred):
  return (1-dice_coef(y_true, y_pred)
