add a column to a csv file with some robust handling

add_column_to_csv.py

import csv, os


def add_csv_column(filename: str, column_name: str, data: list) -> None:
    """
    Add a column of data to an existing csv file

    pads with empty string if data size does not match target csv

    :param filename: path to csv file
    :param column_name: name of new column
    :param data: list of data
    """
    path, file = os.path.split(filename)
    tempfile = os.path.join(path, '~' + file)
    with open(filename, 'r') as csvinput, open(tempfile, 'w') as csvoutput:
        writer = csv.writer(csvoutput, lineterminator='\n')
        reader = csv.reader(csvinput)
        all = []
        row = next(reader)
        row.append(column_name)
        all.append(row)
        data.reverse()
        number_of_cols = len(row[0])

        for row in reader:
            row.append(data.pop() if data else '')
            all.append(row)

        while data:
            all.append(([''] * number_of_cols) + [data.pop()])
        writer.writerows(all)
        os.remove(filename)
        os.rename(tempfile, filename)