Dear colleagues, I have a data set that looks roughly like this; mydat<-data.frame(state=c(rep("Alabama", 5), rep("Delaware", 5), rep("California", 5)), news=runif(15, min=0, max=8), cum.news=rep(0, 15))
For each state, I'd like to cumulatively sum the value of "news" and make that put that value in cum.news. I'm trying as follows but I get really weird results. One thing is that it keeps counting 0's as 1. for (i in levels(mydat$state)) { mydat[mydat$state==i, ]$cum.news<-sapply(mydat[mydat$state==i, ]$news, function(x) sum(1:x)) } I can sort of get the same sapply function to do what I want when working on a test string test<-1:10 sapply(test, function(x) sum(1:x)) Any thoughts? Simon Kiss ********************************* Simon J. Kiss, PhD Assistant Professor, Wilfrid Laurier University 73 George Street Brantford, Ontario, Canada N3T 2C9 Cell: +1 905 746 7606 ______________________________________________ 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.