title: Keras Network with 2d Array
body: <p>I have the following input array, which I want to feed to a CNN</p>
  
  <pre><code>import numpy as np 
  from keras.layers import Input, Dense, Conv2D
  #dummy data for 1d array
  width = 5
  levels = 4
  inputArray =np.random.randint(low=0, high=levels, size=20)
  inputArray_ = inputArray.reshape(-1,width) #reshape to 2d array
  </code></pre>
  
  <p>the first layer of the network is:</p>
  
  <pre><code>x = Conv2D(16, (3, 3), activation='relu', padding='same')(inputArray_)
  </code></pre>
  
  <p>I get the following error:</p>
  
  <pre><code>ValueError: Layer conv2d_13 was called with an input that isn't a symbolic tensor.   Received type: &lt;class 'numpy.ndarray'&gt;. Full input: [array([[3, 1, 1, 1, 1],
     [0, 1, 3, 1, 3],
     [0, 0, 2, 0, 0],
     [1, 3, 2, 2, 0],
     [1, 1, 2, 1, 1],
     [0, 3, 1, 3, 0],
     [3, 1, 2, 3, 2],
     [1, 2, 0, 2, 2],
     [3, 2, 2, 1, 0],
     [1, 2, 1, 3, 1],
     [0, 3, 2, 3, 0],
     [0, 3, 1, 0, 0],
     [2, 2, 0, 0, 2],
     [2, 2, 1, 0, 1],
     [3, 3, 0, 3, 1],
     [0, 0, 3, 1, 0],
     [1, 3, 1, 2, 2],
     [1, 0, 3, 2, 2],
     [3, 1, 2, 1, 2],
     [3, 0, 3, 3, 1]])]. All inputs to the layer should be tensors.
  </code></pre>