title: How to get the key from a dataframe in pandas
body: <p>I am following the "<a href="https://tsfresh.readthedocs.io/en/latest/text/quick_start.html" rel="nofollow noreferrer">Quick Start</a>" code of tsfresh python package (<code>pip install tsfresh</code>) as follows.</p>
  
  <pre><code>from tsfresh.examples.robot_execution_failures import download_robot_execution_failures, \
      load_robot_execution_failures
  download_robot_execution_failures()
  timeseries, y = load_robot_execution_failures()
  from tsfresh import extract_features
  extracted_features = extract_features(timeseries, column_id="id", column_sort="time")
  
  import pandas as pd
  extracted_features.to_csv("file.csv")
  </code></pre>
  
  <p>The <code>extracted_features</code> is a pandas dataframe. It has an <code>id</code> column when I write it to the <code>csv</code> file as shown in the image.</p>
  
  <p><a href="https://i.stack.imgur.com/Wybp0.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Wybp0.jpg" alt="enter image description here"></a></p>
  
  <p>However, when I try to retrieve it as <code>extracted_features[["id"]]</code>, I get an error as <code>KeyError: "['id'] not in index"</code>. Is there a way to solve this issue.</p>
  
  <p>I am happy to provide more details if needed.</p>