Dear R-helper, I am working on a very large data frame and I am trying to add a new column and write in it with certain conditions. I have try to use this code with the data frame p :
ID = 0 p[,"newColumn"]<- ifelse (p$flagFoehn3_durr == 1, ifelse(p$Guetsch == 0, ID <<- ID ++ , ID ) , 0 ) What I am trying to do is to increment the ID when p$Guetsch == 0 and to put this result in the column. The problem is that ID does not increment itself. An other way is to use a loop for like this example : ID = 0 for (s in 1:(nrow(z))){ z[s,"newColumn"]<- if (z$flagFoehn3_durr[s] == 1){ if(z$flagFoehn3_durr[s-1] == 0){ ID <<-ID+1 }else{ ID } }else{ 0 } } This work perfectly, but the problem is that it will take me more than a month to run it. Is there a way to increment with the first code I used or a way of running the second code faster (I have more than 1 million rows) Thanks! Cheers, Damien [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.