Does anyone know how to do a multi-column sort, using column-wise permutations?
Is this the right approach? Thinking out loud here.
A multi-column sort is really a precedence sort. You only need to sort on a secondary or tertiary key if the primary key has equivalent values.
1) sort on next property 2) if any more properties groupby property else goto 4 3) foreach groupby subview go to 1 4) reassemble final indices
Result -> stable sort, I think :)
Hopefully I'm being clear. Here is a stupid diagram in the form of a tree structure:
view -> column1 -> groupby -> column 2 -> groupby -> sort -> Final indices
sort column1 sort on subview
A subview -> 1 2
B subview -> 7
8
This seems to be less work overall and might utilize metakit's tech a little better.
I have a half-baked python implementation that requires an index column (mainly because the groupby method doesn't keep track of the row index)
The best-time complexity should be less as well as the size of the sorts should decrease the further down the tree you go.
Brian
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