def split_data(data, training_size=0.8):
  """
  data: Pandas Dataframe
  training_size: proportion of the data to be used for training
  This function splits the data into training_set and test_set based on the given training_size
  Return: train_set and test_set as pandas DataFrame
  """
  return data[:int(training_size*len(data))], data[int(training_size*len(data)):]