Tensorflow reshape with variable length
<p>I'm using the following reshape in my model:</p>

<pre><code>data = tf.placeholder(tf.float32, shape = (BATCH_SIZE, N_CHUNK, WIN * N_SENSOR))

data_flattened = tf.reshape(data, [BATCH_SIZE*N_CHUNK, WIN*N_SENSOR])
</code></pre>

<p>Now I want N_CHUNK to be variable (i.e. NONE in the dimension). How do I implement the reshape? Does the None dimension must be the first dimension?</p>