title: Convert Q1-Q4 period strings to datetime using pandas
body: <p>Here is a sample with date format:</p>
  
  <pre><code>data = pd.DataFrame({'Quarter':['Q1_01','Q2_01', 'Q3_01', 'Q4_01', 'Q1_02','Q2_02']
                       , 'Sale' :[10, 20, 30, 40, 50, 60]})
  
  print(data)
  
  #   Quarter  Sale
  #0  Q1_01    10
  #1  Q2_01    20
  #2  Q3_01    30
  #3  Q4_01    40
  #4  Q1_02    50
  #5  Q2_02    60
  
  print(data.dtypes)
  # Quarter    object
  # Sale        int64
  </code></pre>
  
  <p>Would like to convert Quarter column into Pandas datetime format like
  '<strong>Jan-2001</strong>' or '<strong>01-2001</strong>' that can be used in <strong><em>fbProphet</em></strong> for time series analysis.</p>
  
  <p>Tried using strptime but got an error <code>TypeError: strptime() argument 1 must be str, not Series</code></p>
  
  <pre><code>from datetime import datetime
  
  data['Quarter'] = datetime.strptime(data['Quarter'], 'Q%q_%y')
  </code></pre>
  
  <p>What is the cause of the error ? Any better solution?</p>