Hello,You have to convert y1 to class "Date" first, then do date arithmetic. The complete code would be
dat<-read.table(text=" y1, flag 24-01-2016,S 24-02-2016,R 24-03-2016,X 24-04-2016,H 24-01-2016,S 24-11-2016,R 24-10-2016,R 24-02-2016,X 24-01-2016,H 24-11-2016,S 24-02-2016,R 24-10-2016,X 24-03-2016,H 24-04-2016,S ",sep=",",header=TRUE) str(dat) # See what we have, y1 is a factor dat$y1 <- as.Date(dat$y1, format = "%d-%m-%Y") str(dat) # now y1 is a Date dat$x1 <- cumsum(dat$flag == "S") dat$z2 <- unlist(tapply(dat$y1, dat$x1, function(y) y - y[1])) dat Instead of y - y[1] you can also use ?difftime. Rui Barradas Em 14-10-2016 20:06, Val escreveu:
Thank you Rui, It Worked! How about if the first variable is date format? Like the following dat<-read.table(text=" y1, flag 24-01-2016,S 24-02-2016,R 24-03-2016,X 24-04-2016,H 24-01-2016,S 24-11-2016,R 24-10-2016,R 24-02-2016,X 24-01-2016,H 24-11-2016,S 24-02-2016,R 24-10-2016,X 24-03-2016,H 24-04-2016,S ",sep=",",header=TRUE) dat dat$x1 <- cumsum(dat$flag == "S") dat$z2 <- unlist(tapply(dat$y1, dat$x1, function(y) y - y[1])) error message In Ops.factor(y, y[1]) : ‘-’ not meaningful for factors On Thu, Oct 13, 2016 at 5:30 AM, Rui Barradas <ruipbarra...@sapo.pt> wrote:Hello, You must run the code to create x1 first, part 1), then part 2). I've tested with your data and all went well, the result is the following.dput(dat)structure(list(y1 = c(39958L, 40058L, 40105L, 40294L, 40332L, 40471L, 40493L, 40533L, 40718L, 40771L, 40829L, 40892L, 41056L, 41110L, 41160L, 41222L, 41250L, 41289L, 41324L, 41355L, 41415L, 41562L, 41562L, 41586L), flag = structure(c(3L, 2L, 4L, 1L, 3L, 2L, 2L, 4L, 1L, 3L, 2L, 4L, 1L, 3L, 2L, 2L, 2L, 2L, 4L, 2L, 4L, 4L, 1L, 3L), .Label = c("H", "R", "S", "X"), class = "factor"), x1 = c(1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 5L), z2 = c(0L, 100L, 147L, 336L, 0L, 139L, 161L, 201L, 386L, 0L, 58L, 121L, 285L, 0L, 50L, 112L, 140L, 179L, 214L, 245L, 305L, 452L, 452L, 0L)), .Names = c("y1", "flag", "x1", "z2"), row.names = c(NA, -24L), class = "data.frame") Rui Barradas Em 12-10-2016 21:53, Val escreveu:Rui, Thank You! the second one gave me NULL. dat$z2 <- unlist(tapply(dat$y1, dat$x1, function(y) y - y[1])) dat$z2 NULL On Wed, Oct 12, 2016 at 3:34 PM, Rui Barradas <ruipbarra...@sapo.pt> wrote:Hello, Seems simple: # 1) dat$x1 <- cumsum(dat$flag == "S") # 2) dat$z2 <- unlist(tapply(dat$y1, dat$x1, function(y) y - y[1])) Hope this helps, Rui Barradas Em 12-10-2016 21:15, Val escreveu:Hi all, I have a data set like dat<-read.table(text=" y1, flag 39958,S 40058,R 40105,X 40294,H 40332,S 40471,R 40493,R 40533,X 40718,H 40771,S 40829,R 40892,X 41056,H 41110,S 41160,R 41222,R 41250,R 41289,R 41324,X 41355,R 41415,X 41562,X 41562,H 41586,S ",sep=",",header=TRUE) First sort the data by y1. Then I want to create two columns . 1. the first new column is (x1): if flag is "S" then x1=1 and assign the following/subsequent rows 1 as well. When we reach to the next "S" then x1=2 and the subsequent rows will be assigned to 2. 2. the second variable (z2). Within each x1 find the difference between the first y1 and subsequent y1 values Example for the first few rows y1, flag, x1, z2 39958, S, 1, 0 z2 is calculated as z2=(39958, 39958) 40058, R, 1, 100 z2 is calculated as z2=(40058, 39958) 40105, X, 1, 147 z2 is calculated as z2=(40105, 39958) 40294, H, 1, 336 z2 is calculated as z2=(40294, 39958) 40332, S, 2, 0 z2 is calculated as z2=(40332, 40332) etc Here is the complete output for the sample data 39958,S,1,0 40058,R,1,100 40105,X,1,147 40294,H,1,336 40332,S,2,0 40471,R,2,139 40493,R,2,161 40533,X,2,201 40718,H,2,386 40771,S,3,0 40829,R,3,58 40892,X,3,121 41056,H,3,285 41110,S,4,0 41160,R,4,50 41222,R,4,112 41250,R,4,140 41289,R,4,179 41324,X,4,214 41355,R,4,245 41415,X,4,305 41562,X,4,452 41562,H,4,452 41586,S,5,0 Val ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
