title: How to insert certain values to a tensor in tensorflow?
body: <p>I want to convert</p>
  <pre><code>from = [
      [1],[2],[3],[4],
  ]
  </code></pre>
  <p>shape (4, 1)</p>
  <p>this tensor</p>
  <pre><code>to = [
      [1,1],[2,2],[3,3],[4,4],
  ]
  </code></pre>
  <p>shape (4, 2)</p>
  <p>this tensor.</p>