title: How to replace one column by a value in a numpy array?
body: <p>I have an array like this</p>
  
  <pre><code>import numpy as np
  
  a = np.zeros((2,2), dtype=np.int)
  </code></pre>
  
  <p>I want to replace the first column by the value <code>1</code>. I did the following:</p>
  
  <pre><code>a[:][0] = [1, 1] # not working
  a[:][0] = [[1], [1]] # not working
  </code></pre>
  
  <p>Contrariwise, when I replace the rows it worked!</p>
  
  <pre><code>a[0][:] = [1, 1] # working
  </code></pre>
  
  <p>I have a big array, so I cannot replace value by value.</p>