title: tf.estimator package not installed
body: <p>My <code>tensorflow-gpu</code> was running fine before. But now it is giving me this error: </p>
  
  <pre><code>tf.estimator package not installed.
  </code></pre>
  
  <p>when import is invoked: </p>
  
  <pre><code>user@pc:~/workspace$ python
  Python 2.7.15rc1 (default, Nov 12 2018, 14:31:15) 
  [GCC 7.3.0] on linux2
  Type "help", "copyright", "credits" or "license" for more information.
  &gt;&gt;&gt; import tensorflow as tf
  tf.estimator package not installed.
  tf.estimator package not installed.
  &gt;&gt;&gt; 
  </code></pre>
  
  <p>I have googled it and installed <code>pandas</code> and <code>matplotlib</code> as suggested in <a href="https://github.com/tensorflow/tensorflow/issues/23007" rel="nofollow noreferrer">this</a> link but is still did not work. </p>
  
  <p>Any solution?</p>