3 different ways to format a table.

format_table.py

from itertools import starmap


def format_table(table, delim='|'):
    """
    :param list table: 2D list, with inner lists of strings as rows.
    :param str delim: Used to define table cell borders.
    :return list: Containing formatted string elements representing each row,
                  ready to be written to a file.
    """
    assert len(set(len(row) for row in table)) == 1, "'table' param has rows of differing lengths"
    col_widths = [len(max(col, key=len)) for col in zip(*table)]
    left_justify = lambda cell, width: '{{:<{}}}'.format(width).format(cell)
    justify_cells = lambda cells: starmap(left_justify, zip(cells, col_widths))
    make_row = lambda cells: ' {} '.format(delim).join(justify_cells(cells))
    make_line = lambda cells: '{0} {1} {0}\n'.format(delim, make_row(cells))
    return [make_line(row) for row in table]


def format_table_with_map(table, delim='|'):
    col_widths = [len(max(col, key=len)) for col in zip(*table)]
    rows_with_widths = map(lambda row: zip(row, col_widths), table)
    justified_cells = map(
        lambda row: starmap(lambda cell, width: '{{:<{}}}'.format(width).format(cell), row),
        rows_with_widths)
    joined_rows = map(lambda row: ' {} '.format(delim).join(row), justified_cells)
    return list(map(lambda row: '{0} {1} {0}\n'.format(delim, row), joined_rows))


def format_table_list_comp(table, delim='|'):
    col_widths = [len(max(col, key=len)) for col in zip(*table)]
    padded_delim = ' {} '.format(delim)
    left_justify = lambda cell, width: '{{:<{}}}'.format(width).format(cell)
    return [
        '{0} {1} {0}\n'.format(
            delim,
            padded_delim.join([left_justify(cell, width) for cell, width in zip(row, col_widths)]))
        for row in table
    ]


def format_table_pythonic(table, delim='|'):
    col_widths = [max(map(len, col)) for col in zip(*table)]
    left_justified_cell_templates = [' {:<%d} ' % width for width in col_widths]
    row_template = '{0}{1}{0}\n'.format(delim, delim.join(left_justified_cell_templates))
    return [row_template.format(*row) for row in table]

col_widths = [max(map(len, col)) for col in zip(*table)]