def column(data, key):
  """ get specific column

  Args:
      data (list(dict)): data object returned by csv.DictReader
      key (str): name of the column (header in first row)

  Returns:
      list(float): column data
  """
  column_data = []
  for row in data:
    column_data.append(float(row[key]))
  return column_data