title: AttributeError: 'Str' Object Has No Attribute 'Mean_validation_score' in python
body: <p>This error occurs in my code: AttributeError: 'str' object has no attribute 'mean_validation_score'. What can I do to resolve it?</p>
  
  <pre><code>GridMean = [result.mean_validation_score for result in 
  gridA.cv_results_]
  print(GridMean)
  plt.plot(k_values, GridMean)
  plt.xlabel('Value of "K" for KNN')
  plt.ylabel('CrossValidated Accuracy')
  </code></pre>