On Wed, Sep 30, 2020 at 2:44 AM Steven D'Aprano <st...@pearwood.info> wrote:
> On Sun, Sep 27, 2020 at 07:59:18AM -0300, Sebastian Kreft wrote: > > > Hi Steven, could you share some examples of what you have in mind. > Having a > > more concrete example of an API that would benefit from > mixed-subscripting > > would allow us to better understand its usefulness. > > I have an experimental Matrix class: > > https://en.wikipedia.org/wiki/Matrix_(mathematics) > > There are (at least) three indexing operations needed: > > - row > - column > - individual cell > > The first two support get, set and delete; the last supports > only get and set. > > One obvious API would be a keyword to disambiguate between the first two > cases: > > matrix[3, 4] # unambiguously a cell reference > matrix[3] # ambiguous, forbidden > matrix[3, axis='row'] # unambiguously a row > matrix[3, axis='col'] # unambiguously a column > Have you considered using matrix[row=3], matrix[col=3]? In that case it would be a keyword only access. What advantages do you see with your current API? Or alternatively, using numpy's current syntax matrix[3, :], matrix[:, 3] (maybe `...` could be another option, if `:` is too magic) > > These could be supported for all of get, set and delete (except for > cells) operations. A quick sketch of the implementation with minimal > error checking for brevity: > > > def __setitem__(self, index, value, *, axis=None): > if isinstance(index, tuple): > # Operate on a cell. > if axis is not None: > raise TypeError('cell ops don't take axis keyword') > i, j = index > ... # bind a single cell > > elif isinstance(index, int): > if axis == 'row': > ... # bind the row > elif axis == 'col': > ... # bind the column > else: > raise ValueError('bad axis') > > else: > raise TypeError > > > -- > Steve > _______________________________________________ > Python-ideas mailing list -- python-ideas@python.org > To unsubscribe send an email to python-ideas-le...@python.org > https://mail.python.org/mailman3/lists/python-ideas.python.org/ > Message archived at > https://mail.python.org/archives/list/python-ideas@python.org/message/CGMHA4LIE6EIFJWLQ5SEMLQWPKRCIY2V/ > Code of Conduct: http://python.org/psf/codeofconduct/ > -- Sebastian Kreft
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