In numpy, what does selection by [:,None] do? : <p>I'm taking the Udacity course on deep learning and I came across the following code:</p>

<pre><code>def reformat(dataset, labels):
    dataset = dataset.reshape((-1, image_size * image_size)).astype(np.float32)
    # Map 0 to [1.0, 0.0, 0.0 ...], 1 to [0.0, 1.0, 0.0 ...]
    labels = (np.arange(num_labels) == labels[:,None]).astype(np.float32)
    return dataset, labels
</code></pre>

<p>What does <code>labels[:,None]</code> actually do here?</p>
