Pretty print list of strings like BSD `ls`

fmtstrings_like_ls.py

import math
import itertools
import shutil

# https://gist.github.com/kkew3/8bb9aa225a6c82ae5e1a0fa609c9a65a
import cjkjust


def calc_layout(n_strings, total_width, column_width, width_between_cols):
    # expected_ncols * column_width +
    #     (expected_ncols - 1) * width_between_cols <= total_width
    #
    #   -> expected_ncols <= (total_width + width_between_cols) /
    #                        (column_width + width_between_cols)
    #
    # Therefore, expected_ncols is at most the floor of the RHS
    expected_ncols = math.floor((total_width + width_between_cols) /
                                (column_width + width_between_cols))
    expected_ncols = max(expected_ncols, 1)
    actual_nrows = math.ceil(n_strings / expected_ncols)
    actual_ncols = (n_strings - 1) // actual_nrows + 1
    return actual_nrows, actual_ncols


def pprint(strings, total_width=None, width_between_cols=1, file=None) -> None:
    """
    Pretty print list of strings like ``ls``.

    :param strings: list of strings
    :param total_width: the disposable total width, default to terminal width
    :param width_between_cols: width between columns, default to 1
    :param file: file handle to which to print, default to stdout
    """
    total_width = total_width or shutil.get_terminal_size().columns
    assert total_width >= 1, total_width
    assert width_between_cols >= 1, width_between_cols

    if not strings:
        return

    column_width = max(map(cjkjust.cjklen, strings))
    nrows, ncols = calc_layout(
        len(strings), total_width, column_width, width_between_cols)
    columns = [[] for _ in range(ncols)]
    for i, s in enumerate(strings):
        columns[i // nrows].append(s)

    for row in itertools.zip_longest(*columns):
        padded_row = (cjkjust.cjkljust(s or '', column_width) for s in row)
        print((' ' * width_between_cols).join(padded_row), file=file)