search for: posfut

...200", "14.9200", "14.9200", "14.9200", "14.9200" )), .Names = c("DESCRIPTION", "CREATED.DATE", "QUANTITY", "SETTLEMENT"), row.names = c(NA, 12L), class = "data.frame") Here is the line I pass : >PosFut=ddply(futures, c("DESCRIPTION","SETTLEMENT"), summarise, POSITION= sum(QUANTITY))[,c(1,3,2)] And here the result : PosFut <- structure(list(DESCRIPTION = structure(1:3, .Label = c("CORN Jul/10", "LIVE CATTLE Aug/10", "SUGAR NO.11 Jul/10"), cla...

..."14.9200", "14.9200", "14.9200" )), .Names = c("DESCRIPTION", "CREATED.DATE", "QUANTITY", "SETTLEMENT"), row.names = c(NA, 12L), class = "data.frame") I need then to apply to the df this following code line : >PosFut=ddply(futures, c("DESCRIPTION","SETTLEMENT"), summarise, POSITION= sum(QUANTITY))[,c(1,3,2)] It works perfectly in most of case, BUT I have a new problem: it can sometime occurs that my df "futures" is empty, with zero rows. futures <- structure(list(DESCRIPTION...