Return the matrix representation of the genetic map.

    :arg inputfile: the path to the input file from which to retrieve the
        genetic map.
    :arg sheet_name: the excel sheet containing the data on which to
        retrieve the genetic map.

def get_map_matrix(inputfile, sheet_name):
    """ Return the matrix representation of the genetic map.

    :arg inputfile: the path to the input file from which to retrieve the
        genetic map.
    :arg sheet_name: the excel sheet containing the data on which to
        retrieve the genetic map.

    """
    matrix = read_excel_file(inputfile, sheet_name)
    output = [['Locus', 'Group', 'Position']]
    for row in matrix:
        if row[0] and not re.match(r'c\d+\.loc[\d\.]+', row[0]):
            output.append([row[0], row[1], row[2]])
    return output