title: Delete a column from TFRecord Dataset (for feature selection)
body: <p>I am trying to implement a Feature Selection component with the following plan in mind:</p>
  <h3>The implementation</h3>
  <ul>
  <li>Component takes and <code>InputArtifact[Example]</code> as input</li>
  <li>Since the data is stored in the form of TFRecords in the URI of the input artifact, I convert it into compatible numpy dictionaries and use sklearn to come up with the list of features selected</li>
  <li>I delete the required features from the input example <strong>directly</strong> to produce put it in <code>OutputArtifact[Example]</code> (which has the same structure but fewer columns)</li>
  </ul>
  <p>I am done with the first and second point, but am not able to figure out how to delete the selected columns directly in the TFRecord Dataset itself (which I am getting using <code>tf.data.TFRecordDataset(train_uri, compression_type='GZIP')</code>)</p>