As a result of some computations using data.table wherein the computations require using "i" to select certain rows, the results of the computations only reside in those certain rows. Further computations require that the computation results be in each row by group. A much simplified example follows.
help_request_120116.R <http://r.789695.n4.nabble.com/file/n4726956/help_request_120116.R> Not being familiar with the nabble upload feature, I have also done a cut and paste. # adding data to data.table column library(data.table) dt1 <- data.table(group = rep(1:5, each = 3),b = rep(1:3,times = 5), var = c(NA,NA,NA,20,NA,NA,21,NA,NA,NA,NA,NA,22,NA,NA), var1 = c(NA,NA,NA,20,NA,NA,20,NA,NA,NA,NA,NA,20,NA,NA)) dt1 # Result Wanted # group b var var1 #1: 1 1 NA 20 #2: 1 2 NA 20 #3: 1 3 NA 20 #4: 2 1 20 20 #5: 2 2 NA 20 #6: 2 3 NA 20 #7: 3 1 21 20 #8: 3 2 NA 20 #9: 3 3 NA 20 #10: 4 1 NA 20 #11: 4 2 NA 20 #12: 4 3 NA 20 #13: 5 1 22 20 #14: 5 2 NA 20 #15: 5 3 NA 20 I have searched the web, books, vignette, FAQs and fumbled around trying this and that for the last week or so with no success. The solution is probably very simple and I hate to waste your time with something this basic, but I just cannot get my head wrapped around how to this. BTW, love the package, use setkey and by all the time. Carl Sutton ----- Carl Sutton -- View this message in context: http://r.789695.n4.nabble.com/filing-a-column-with-a-number-from-another-column-by-group-tp4726956.html Sent from the datatable-help mailing list archive at Nabble.com. _______________________________________________ datatable-help mailing list datatable-help@lists.r-forge.r-project.org https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help
