title: Python pandas removing SettingWithCopyWarning
body: <p>So I made an empty dataframe using</p>
  
  <pre><code>df=data[['ID','Matrix','Name','Country', 'Units']]
  df['Value']=''
  </code></pre>
  
  <p>and I am filling it in with code like this, which finds strings containing values of 'Good', 'Bad' in <code>df.Matrix</code> and filling them with values in <code>sch[i]</code>:</p>
  
  <pre><code>df.loc[df.Matrix.str.contains('Good'),'Value'] = sch[2]
  df.loc[df.Matrix.str.contains('Bad'),'Value'] = sch[6]
  df.loc[df.Matrix.str.contains('Excellent'),'Value'] = sch[8]
  </code></pre>
  
  <p>I have been getting a bunch of errors like both of these two different ones:</p>
  
  <pre><code>C:\Python33\lib\site-packages\pandas\core\strings.py:184: UserWarning: This pattern has match groups. To actually get the groups, use str.extract.
    " groups, use str.extract.", UserWarning)
  
  C:\Users\0\Desktop\python\Sorter.py:57: SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame
    df.loc[df.Matrix.str.contains('Bad'),'Value'] = sch[6]
  </code></pre>
  
  <p>So far I am suppressing the code using</p>
  
  <pre><code>pd.options.mode.chained_assignment = None
  </code></pre>
  
  <p>If I do not suppress the error messages I will get about 20 of them. Is there another format I can change the data so that I do not get the error message?</p>
  
  <p>I am using python 3 and pandas 0.131 if it helps</p>