title: Insert a row and delete rows in dataframes in a dictionary using pandas
body: <p>I have a dictionary containing multiple dataframes, and my dataframes (examples df1 and df2) have the same structure the key to each dataframe in my dict is the id presents in the dataframe (so 'AA' for df1). </p>
  
  <p>I have a data frame (data_extract), not in the dictionary, I would like to add the date in that dataframe to the dataframe in the dictionary with the same id and then add a value and then delete all the dates before the one in data_extract. At the end I want something like df1_bis and df2_bis.</p>
  
  <p>I was thinking about using concat but I'm not sure it is the best idea because in my script I need to delete some rows and I thought modifying each dataframe was more efficient and logical. For the dates I thought about using the calendar day but then again I don't know if it's a good idea and how to use it.</p>
  
  <pre><code>a = pd.concat(mydict.values(), ignore_index=True)
  
  df1 = pd.DataFrame({'id': ['AA', 'AA','AA', 'AA','AA'],
                      'date' : ['01/01/2015', '07/01/2015','19/01/2015', '01/02/2015','08/02/2015'],
                      'value' :  [7,9,1,6,7],
                      'date_y' : [1,7,19,32,39]
                              })
  
  df2 = pd.DataFrame({'id': ['BB', 'BB','BB', 'BB','BB'],
                      'date' : ['09/01/2015', '17/01/2015','19/02/2015', '01/03/2015','08/03/2015'],
                      'value' :  [8,9,9,6,17],
                      'date_y' : [9,17,50,60,67],
                              })
  
  data_extract = pd.DataFrame({'id': ['AA', 'BB'],
                      'date' : ['03/02/2015', '01/02/2015']
                              })
  
  
  df1_bis = pd.DataFrame({'id': ['AA', 'AA','AA'],
                      'date' : ['01/02/2015','03/02/2015','08/02/2015'],
                      'value' :  [6,'something',7],
                      'date_y' : [32,34 ,39]
                              })
  
  df2_bis = pd.DataFrame({'id': ['BB', 'BB','BB', 'BB','BB'],
                      'date' : ['17/01/2015', '01/02/2015','19/02/2015', '01/03/2015','08/03/2015'],
                      'value' :  [9,'something',9,6,17],
                      'date_y' : [17,32, 50,60,67],
                              })
  </code></pre>