Support for grouped ds in bind
Opened this issue · 3 comments
bind function:
bind doesn't support grouped ds as mentioned here:
https://clojurians.zulipchat.com/#narrow/stream/151763-beginners/topic/tablecloth.3A.20adding.20sum.20to.20bottom.20of.20column/near/244847145
--I would be happy to provide a PR
Great. I'll take a look at this at the end of the week.
Ok! I'm ready for a discussion (we can move it to Zulip)
bind (along with all the joins and other functions combining two and more datasets) doesn't work on grouped dataset now. During initial implementation I left it since there are some deeper issues to solve. Here is the summary.
We have to consider 4 different input combinations (X - an operation, eg. bind, ds - regular dataset, gds - grouped dataset):
(X left-ds right-ds)(X gds ds)(X ds gds)(X left-gds right-gds)
Ad.1 - this is implemented, function returns a new dataset
Ad.2. - this can be implemented the naive way, bind separatelly for each group using the same ds. Returns grouped dataset.
Ad.3. - I have no idea here :) The safest would be raise an exception. The second option is to ungroup gds and bind two regular datasets.
Ad.4. - The most complicated part. Possible option is: bind only matching groups, using left-gds as a main dataset. If there is no matching group in the right-gds, leave this group unchanged.
What do you think?
Note: this can apply for every function in join-concat namespace.