title: name 'StandardScaler' is not defined
body: <p>I have installed <code>scikit-learn 0.23.2</code> via <code>pip3</code>, however, I get this error from my code</p>
  <pre><code>Traceback (most recent call last):
    File &quot;pca_iris.py&quot;, line 12, in &lt;module&gt;
      X = StandardScaler().fit_transform(X)
  NameError: name 'StandardScaler' is not defined
  </code></pre>
  <p>I searched the web and saw similar topics, however the version is correct and I don't know what to do further. The line <code>import sklearn</code> is in the top of the script.</p>
  <p>Any thought?</p>