title: TypeError: ufunc 'invert' not supported for input types,
body: <p>I have cloned the repository for U-net with tensorflow.</p>
  <pre><code>labels = np.zeros((ny, nx, self.n_class), dtype=np.float32)
  labels[..., 1] = label
  labels[..., 0] = ~label
  </code></pre>
  <p>I get an error in the 3rd line saying:</p>
  <p><strong>TypeError</strong>: ufunc '<strong>invert</strong>' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''<strong>safe</strong>''</p>
  <p>How do I debug this?</p>