fix afterpoint of numbers with thousand separators resulting in correct decimal alignment

[alexandergazo]

Fixes #130. It arrises as the function _afterpoint fails to recognize numbers with thousand separators. This happens because the function _afterpoint relies on the function _isnumber which relies on the built-in function float.__init__ which fails on thousand-separated numbers.

I did not change the function _isnumber as numbers such as "123,123" are to be aligned as plain text, resulting from the issue #110 and subsequent pulls and tests (test/test_regression.py::test_string_with_comma_between_digits_without_floatfmt_grouping_option).

The solution is therefore implemented in the function _afterpoint by checking not only _isnumber but also a new function __isnumber_with_thousands_separator which validates floats or ints with thousand separators in [byte]string form. This is done by regex r"^(([+-]?[0-9]{1,3})(?:,([0-9]{3}))*)?(?(1)\.[0-9]*|\.[0-9]+)?$" which simply optionally matches signs, then the leading group, then separated thousands, and then the decimal part. A decimal part is required if the non-decimal part is empty.

The tests were implemented only for the function tabulate._align_column.

[Erotemic]

Any chance this could be merged soon? I just ran into this issue, and it would be nice to have it fixed.

I took a look at the code and it seemed fine to me. I also checked out the branch and verified that the solution works in my case.

Using the current "main" branch:

In [2]:     import tabulate
   ...:     data = [
   ...:         [13213.2, 3213254.23, 432432.231,],
   ...:         [432432., 432.3, 3.2]
   ...:     ]
   ...:     print(tabulate.tabulate(data, headers=['a', 'b'], floatfmt=',.02f'))
   ...:     print(tabulate.tabulate(data, headers=['a', 'b'], floatfmt='.02f'))
   ...: 
                          a              b
----------  ---------------  -------------
 13,213.20  3,213,254.23     432,432.23
432,432.00           432.30           3.20
                    a          b
---------  ----------  ---------
 13213.20  3213254.23  432432.23
432432.00      432.30       3.20

Using this branch:

In [3]:     import tabulate
   ...:     data = [
   ...:         [13213.2, 3213254.23, 432432.231,],
   ...:         [432432., 432.3, 3.2]
   ...:     ]
   ...:     print(tabulate.tabulate(data, headers=['a', 'b'], floatfmt=',.02f'))
   ...:     print(tabulate.tabulate(data, headers=['a', 'b'], floatfmt='.02f'))
                       a           b
----------  ------------  ----------
 13,213.20  3,213,254.23  432,432.23
432,432.00        432.30        3.20
                    a          b
---------  ----------  ---------
 13213.20  3213254.23  432432.23
432432.00      432.30       3.20