title: How to add a column to array?
body: <p>I have an array:
  <a href="https://i.stack.imgur.com/vFnJx.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vFnJx.png" alt="enter image description here"></a></p>
  
  <p>Then I used talib to calculate the EMA by <code>x=talib.EMA(ar[:,[2][0]].astype(np.double), 2)</code>, I am not sure if this is the right way though, because I need <code>[0]</code> after specify all rows of column 2, then I get:</p>
  
  <p><a href="https://i.stack.imgur.com/ieI61.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ieI61.png" alt="enter image description here"></a></p>
  
  <p>How can I add it to the last column of orginal array so it looks like this? </p>
  
  <p><a href="https://i.stack.imgur.com/Mmsmu.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Mmsmu.png" alt="enter image description here"></a>
  Thanks</p>