title: Cannot read f1-score from csv file
body: <p>i am reading classification_report file after doing 10 fold cv</p>
  <pre><code>for i in _all_files:
      print(i)
      df = pd.read_csv(i)
  
  
      saved_column = df.f1-score
      a = saved_column[5]
      li.append(a)
  </code></pre>
  <p>I want to add f1-score and find mean. But I am getting below error:</p>
  <pre><code>AttributeError: 'DataFrame' object has no attribute 'f1'
  </code></pre>
  <p>I am able to fetch accuracy, precision and recall score using above code but bot f2-score.</p>