title: Numpy add array of shape NxD to NxK into the first D in array NxK
body: <p>I have two arrays</p>
  <pre><code>a = np.array([[0, 0, 2, 3, 4],
                [0, 1, 2, 3, 4],
                [0, 2, 2, 3, 4]])
  </code></pre>
  <p>and</p>
  <pre><code>b = np.array([[1, 1],
                [2, 2],
                [3, 3]])
  </code></pre>
  <p>I want to one array where I am adding the values of <code>b</code> to the first two columns in <code>a</code> like this:</p>
  <pre><code>c = np.array([[1, 1, 2, 3, 4],
                [2, 3, 2, 3, 4],
                [3, 5, 2, 3, 4]])
  </code></pre>
  <p>if it helps you can think of the first two columns in <code>a</code> as the <code>x,y</code> coordinates and <code>b</code> as <code>dx, dy</code>.</p>
  <p>My current method is as follows:</p>
  <pre><code>c = np.concatenate([a[:, 0:2] + b, a[:, 2:]],1)
  </code></pre>
  <p>but I am looking for a better method</p>
  <p>Thank you</p>