Hi, I have a data table with a number of variables and I wish to do some function on each variable, my data table looks like this:
type att1 att2 att3 att4 black 1 2 2 1 white 0 2 1 0 green 4 2 1 0 black 1 1 1 1 green 2 1 2 2 I would like to sum on each attribute by type, so my function will be: dt[,att1type := sum(att1),by = type] The problem is that I want to taht in a loop and don't know how to run on all the columns. dt[,att1type := sum(dt[[i]]),by = type] or dt[,att1type := sum(dt[i]),by = type] doesn't work. Thanks, Kostia -- View this message in context: http://r.789695.n4.nabble.com/Running-on-variables-in-data-table-tp4677480.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
