DisconnectedInputError.py

# -*- coding: utf-8 -*-

import numpy as np
from keras.models import Model
from keras.layers import Input
from keras.layers.core import Dense
import keras.backend as K
from keras.optimizers import RMSprop

learn_rate = 0.00005
batch_size = 512
lamb = 10

def get_gradient_norm(model, y_pred):
    weights = model.trainable_weights
    gradients = model.optimizer.get_gradients(K.mean(y_pred), weights)
    acc = K.sum(K.square(gradients[0]))
    for g in gradients:
        s = K.sum(K.square(g))
        if acc == None:
            acc = s
        else:
            acc = s + acc
    return K.sqrt(acc)

# this loss function, mainly defined through the function above,
# appears to be the culprit. I don't see what is wrong with it however
def make_w_reg_loss(model):
    lvar = K.variable(lamb, name="Lambda")

    def foo(y_true, y_pred):
        gnorm = get_gradient_norm(model, y_pred)
        return lvar * K.square(gnorm - 1)
        
    return foo

def make_critic():
    inp = Input(shape=(2,), name='critic input')
    x = Dense(128, activation="tanh")(inp)
    x = Dense(128, activation="tanh")(x)
    x = Dense(1)(x)
    
    model = Model(inp, x, name="Toy Critic")
    return model

toy_data = np.zeros((7 * 100, 2))

critic = make_critic()

critic.compile(loss=make_w_reg_loss(critic), optimizer=RMSprop(learn_rate))

# not supposed to learn anything, just don't explode please?
X_real_batch = toy_data[np.random.choice(toy_data.shape[0], size=batch_size)]
reg_loss = critic.train_on_batch(X_real_batch, -np.ones(X_real_batch.shape[0]))


print reg_loss

Exception

Traceback (most recent call last):

  File "<ipython-input-31-ba6d4d1a6ec9>", line 1, in <module>
    runfile('/UltraKeks/Dev/nn/wgan/minimal_disconnect.py', wdir='/UltraKeks/Dev/nn/wgan')

  File "/home/cclausen/anaconda2/lib/python2.7/site-packages/spyder/utils/site/sitecustomize.py", line 866, in runfile
    execfile(filename, namespace)

  File "/home/cclausen/anaconda2/lib/python2.7/site-packages/spyder/utils/site/sitecustomize.py", line 94, in execfile
    builtins.execfile(filename, *where)

  File "/UltraKeks/Dev/nn/wgan/minimal_disconnect.py", line 54, in <module>
    reg_loss = critic.train_on_batch(X_real_batch, -np.ones(X_real_batch.shape[0]))

  File "/home/cclausen/anaconda2/lib/python2.7/site-packages/keras/engine/training.py", line 1619, in train_on_batch
    self._make_train_function()

  File "/home/cclausen/anaconda2/lib/python2.7/site-packages/keras/engine/training.py", line 1001, in _make_train_function
    self.total_loss)

  File "/home/cclausen/anaconda2/lib/python2.7/site-packages/keras/optimizers.py", line 197, in get_updates
    grads = self.get_gradients(loss, params)

  File "/home/cclausen/anaconda2/lib/python2.7/site-packages/keras/optimizers.py", line 47, in get_gradients
    grads = K.gradients(loss, params)

  File "/home/cclausen/anaconda2/lib/python2.7/site-packages/keras/backend/theano_backend.py", line 1108, in gradients
    return T.grad(loss, variables)

  File "/home/cclausen/anaconda2/lib/python2.7/site-packages/theano/gradient.py", line 539, in grad
    handle_disconnected(elem)

  File "/home/cclausen/anaconda2/lib/python2.7/site-packages/theano/gradient.py", line 526, in handle_disconnected
    raise DisconnectedInputError(message)

DisconnectedInputError:  
Backtrace when that variable is created:

  File "/home/cclausen/anaconda2/lib/python2.7/site-packages/spyder/utils/site/sitecustomize.py", line 866, in runfile
    execfile(filename, namespace)
  File "/home/cclausen/anaconda2/lib/python2.7/site-packages/spyder/utils/site/sitecustomize.py", line 94, in execfile
    builtins.execfile(filename, *where)
  File "/UltraKeks/Dev/nn/wgan/minimal_disconnect.py", line 48, in <module>
    critic = make_critic()
  File "/UltraKeks/Dev/nn/wgan/minimal_disconnect.py", line 41, in make_critic
    x = Dense(1)(x)
  File "/home/cclausen/anaconda2/lib/python2.7/site-packages/keras/engine/topology.py", line 528, in __call__
    self.build(input_shapes[0])
  File "/home/cclausen/anaconda2/lib/python2.7/site-packages/keras/layers/core.py", line 833, in build
    constraint=self.bias_constraint)
  File "/home/cclausen/anaconda2/lib/python2.7/site-packages/keras/engine/topology.py", line 364, in add_weight
    weight = K.variable(initializer(shape), dtype=K.floatx(), name=name)
  File "/home/cclausen/anaconda2/lib/python2.7/site-packages/keras/backend/theano_backend.py", line 146, in variable
    strict=False)