Hi, May be this helps: If you had showed your solution, it would be easier to compare.
res<-data.frame(lapply(sapply(MyDF[,c(2,4)],function(x) {x1<-which(c(0,diff(x))<0);x1[length(x1)==0]<-0;x1}),`[`,1)) res # TNH BIX #1 3 9 #Speed set.seed(24) MyDFNew<- data.frame(TNH=sample(0:1,1e6,replace=TRUE),BIX=sample(0:1,1e6,replace=TRUE)) system.time(res1<-data.frame(lapply(sapply(MyDFNew,function(x) {x1<-which(c(0,diff(x))<0);x1[length(x1)==0]<-0;x1}),`[`,1))) # user system elapsed # 0.364 0.000 0.363 res1 # TNH BIX #1 7 2 MyDFNew[1:10,] # TNH BIX #1 0 1 #2 0 0 #3 1 1 #4 1 1 #5 1 0 #6 1 0 #7 0 1 #8 1 1 #9 1 1 #10 0 0 A.K. Hi, Hi here i have a dataframe called MyDF. a<-c(1,1,1,1,1,0,0,0,1,1) b<-c(1,1,0,1,1,0,0,0,1,1) c<-c(1,1,1,1,1,1,1,0,1,1) d<-c(1,1,1,1,1,1,1,1,0,1) MyDF<-data.frame(DWATT=a,TNH=b,CSGV=c,BIX=d) My requirement is, here i need a function - to get for a particular row number(s), when particular column(s) value change from one-to-zero (for the first change). Suppose there is no change is happening then it should return "Zero" For example, Using MyDF, DWATT TNH CSGV BIX 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 0 0 1 1 0 0 1 1 0 0 0 1 1 1 1 0 1 1 1 1 Here i want to know, the row number where TNH-column and BIX-column values change happening from one-to-zero for the first time. Note:- Suppose there is no change is happening then it should return "Zero" Answer should be a dataframe with single row. So here answer should return a dataframe like this. TNH BIX ---- ------ 3 9 i used some ways to get a solution using loops. But there is a bulk files with bulk rows to process. So performace is most important. Could someone please suggest better ideas ? Thanks, Antony. ______________________________________________ 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.