I want to make sure I understand you correctly. In the example data.table below, are you looking for d[J(2.1), roll = 1, mult = "all"] to return the same rows (from 'b') as d[J(2), mult = "all"]?
d = data.table(a = c(1,2,2), b = c(1:3), key = 'a') I think that's an interesting feature to have, but it's not obvious that it'll work well with the rest of data.table. A few questions I have - would you want the 'a' column to be the same as currently, i.e. get two rows with a=2.1 in both? What about d[J(c(2.1,2.2)), roll = 1, mult = "all"] - what would that do? What would you set the param defaults to get back current behavior (which arguably is encountered much more frequently)? On Fri, Jun 21, 2013 at 2:16 AM, statquant3 <[email protected]> wrote: > I wrote a post on S.O > > http://stackoverflow.com/questions/17216843/rolling-joins-in-data-table-with-multiple-matches/17219629?noredirect=1#comment24955451_17219629 > > It seems that when "roll" is specified in Y[X, roll=rollValue] even if > there > are several lines of Y that matches one row of X, just one is selected. > I was looking for window joins like in kdb: > http://code.kx.com/wiki/Reference/wj et I was thinking that because all > the > roll logic is already there, may be it would be a good feature to get all > rows matched when roll is specified. > > What do you think ? > > > > -- > View this message in context: > http://r.789695.n4.nabble.com/About-roll-in-data-table-tp4670023.html > Sent from the datatable-help mailing list archive at Nabble.com. > _______________________________________________ > datatable-help mailing list > [email protected] > https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help >
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