DOC: Unused `order` argument in factorize

[TomAugspurger]

def factorize(values, sort=False, order=None, na_sentinel=-1):
    """
    Encode input values as an enumerated type or categorical variable

    Parameters
    ----------
    values : ndarray (1-d)
        Sequence
    sort : boolean, default False
        Sort by values
    order :
    na_sentinel: int, default -1
        Value to mark "not found"

    Returns
    -------
    labels : the indexer to the original array
    uniques : the unique values

    note: an array of Periods will ignore sort as it returns an always sorted PeriodIndex
    """

But it isn't used anywhere. Technically this is an API change, if people aren't using kwargs. So I'll add it to the deprecation list.

[jreback]

gr8!

[jorisvandenbossche]

Wouls there be a reason it was there in the first place?

[TomAugspurger]

I haven't been able to figure that out. I was thinking maybe something to do with sorting, but there's a sort kwarg.

The docstring was added in #4944, but the order line was left untouched.

[jreback]

prob sort related
if u take it out and nothing breaks then prob ok
mostly this is used internally

[jreback]

@wesm what was the original reason for the order kw? (as about to remove it as we deprecated a while back)