keras focal loss theano backend

focal_loss_theano

y_true = 2
y_pred = 0.2

if(K.backend()=="tensorflow"):
    import tensorflow as tf
    sess= tf.Session()
    with tf.device('/cpu:0'):
        pt = tf.where(tf.equal(y_true, 1), y_pred, 1 - y_pred)
    print(sess.run(pt))
if(K.backend()=="theano"):
    import theano as th
    x = th.tensor.dscalar('x')
    y = th.tensor.dscalar('y')
    pt = th.tensor.where(th.tensor.eq(x, 1), y, 1 - y)
    f = th.function([x, y], pt)
    print(f(y_true, y_pred))