title: How to store the information returned from the value_counts() function
body: <p>I have the following dataframe:</p>
  
  <pre><code>      import pandas as pd
        import numpy as np
  
        df_Station_Weather = pd.DataFrame({'ID': [102, 102, 558, 115, 115, 501, 501, 10, 10, 10, 10], 
                                           'Code_Instrument': ['SEN_wider1898', 'SEN_UV', 
                                                               'SEN_wider1898', 'SEN_wider1898', 
                                                               'SEN_rain1015', 'SEN_01', 'SEN_01', 
                                                               'SEN_AD', 'SEN_AD', 'SEN_AD', 
                                                               'SEN_AD']})
  
        print(df_Station_Weather)
  
        ID    Code_Instrument
        102   SEN_wider1898
        102   SEN_UV
        558   SEN_wider1898
        115   SEN_wider1898
        115   SEN_rain1015
        501   SEN_01
        501   SEN_01
        10    SEN_AD
        10    SEN_AD
        10    SEN_AD
        10    SEN_AD
  </code></pre>
  
  <p>I would like to count the number of specific Instruments. So, I did the following:</p>
  
  <pre><code>     list_Instrument = df_Station_Weather['Code_Instrument'].value_counts()
  </code></pre>
  
  <p>I would like to select only the bottom three of the count.  So, I did the following:</p>
  
  <pre><code>      list_Instrument_2 = list_Instrument.head(3)
  </code></pre>
  
  <p>I need to create an array containing the name of the ID of the three largest. It is in this part that I am in doubt.</p>
  
  <p>I tried to build the array with the code:</p>
  
  <pre><code>      array = np.array(list_Instrument_2)
  </code></pre>
  
  <p>However, this created array stores the count values, but I would like it to store the name of the Code_Instrument.</p>
  
  <pre><code>      #Output:
        print(array)
        &gt; array([4, 3, 2], dtype=int64)
  
       # Desired output
       array([SEN_AD, SEN_wider1898, SEN_01]
  </code></pre>
  
  <p>Thank you.</p>