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I'm trying to follow this notebook, problem is it's written for Py 2.7 and I'm trying to port it to Py 3.6. Luckily someone had ported the midi library to Py 3 https://github.com/louisabraham/python3-midi and I was successfully able to use this to parse the midi files into a numpy array. Now my problem is I'm receiving these errors


TypeError                                 Traceback (most recent call last)

<ipython-input-62-f35c20bfe55b> in <module>()

      1 #backward pass, x samples drawn from prob distribution defn by (hk,w,bv)

----> 2 x_sample=gibbs_sample(2)

      3 print(x_sample)

      4 #h sampled from prob distrib defn by (x,w,bh)

      5 h=sample(tf.sigmoid(tf.matmul(x, W) + bh))

<ipython-input-57-943cbc813622> in gibbs_sample(k)

     13     #Gibbs sample(done for k iterations) is used to approximate the distribution of the RBM(defined by W, bh, bv)

     14     ct=tf.constant(0)

---> 15     [_, _, x_sample]=control_flow_ops.while_loop(lambda count, num_iter, *args: count < num_iter,gibbs_step, [ct, tf.constant(k), x], 1, False)

     16     #to stop tensorflow from propagating gradients back through the gibbs step

     17     x_sample=tf.stop_gradient(x_sample)

c:\users\ali\appdata\local\programs\python\python36\lib\site-packages\tensorflow\python\ops\control_flow_ops.py in while_loop(cond, body, loop_vars, shape_invariants, parallel_iterations, back_prop, swap_memory, name, maximum_iterations)

   3051       raise TypeError("body must be callable.")

   3052     if parallel_iterations < 1:

-> 3053       raise TypeError("parallel_iterations must be a positive integer.")


   3055     if maximum_iterations is not None:

TypeError: parallel_iterations must be a positive integer.

I'm also getting strange errors with the shape of the numpy array in the training step

size_tr=tf.cast(tf.shape(x)[0], tf.float32)


W_upd=tf.multiply(eta, tf.subtract(tf.matmul(tf.transpose(x), h), tf.matmul(tf.transpose(x_sample), h_sample)))

bv_upd=tf.multiply(eta, tf.reduce_sum(tf.subtract(x, x_sample), 0, True))

bh_upd=tf.multiply(eta, tf.reduce_sum(tf.subtract(h, h_sample), 0, True))

updt=[W.assign_add(W_upd), bv.assign_add(bv_upd), bh.assign_add(bh_upd)]




for epoch in tqdm(range(epochs)):

            for song in songs:


                #reshaping song into chunks of timestep size


                chunks = int(np.floor(chunks))


                dur = int(np.floor(dur))


                song=np.reshape(song, [chunks, song.shape[1]*timesteps])

                #Train the RBM on batch_size examples at a time

                for i in range(1, len(song), batch_size): 


                    sess.run(updt, feed_dict={x: tr_x})

Error is:

    InvalidArgumentError (see above for traceback): You must feed a value for placeholder tensor 'x_7' with dtype float and shape [?,2340]

         [[Node: x_7 = Placeholder[dtype=DT_FLOAT, shape=[?,2340], _device="/job:localhost/replica:0/task:0/device:CPU:0"]()]]

1 Answer

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by (33.1k points)

The error which you are getting means that  sess.run() call depends on a placeholder which is not been fed. There is only one placeholder, x  in your code and "x_7" in the error  suggests that the placeholder x has been created multiple times.

So, use  tf.reset_default_graph() and then re-execute each of the cells in your notebook in order from top to bottom.By doing this, the error will be fixed.

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