Transform variable number of rows per subject to column variables?
On 9/20/05, Bing Ho <2bingho at stanford.edu> wrote:
Hello, I am very new to R, but I am having trouble with my dataset. I have a data frame where a subject has a variable number of multiple observations for each row, which I wish the transform these observations to column variables. An example of the data frame ID TEST.A TEST.B 1 10 1 1 13 2 1 11 1 2 15 2 2 17 3 And I wish to transform it to the following: ID TEST.A1 TEST.A2 TEST.A3 TEST.B1 TEST.B2 TEST.B3 1 10 13 11 1 2 1 2 15 17 NA 2 3 NA In other words, for the variable number of repeated follow up studies, a new column variable for each subject, but they are grouped by the original test.
First manufacture a "time" column and then use reshape: tt <- sequence(rle(DF$ID)$lengths) reshape(cbind(tt, DF), idvar = "ID", timevar = "tt", direction = "wide") Another possibility is to use the reshape package: library(reshape) DF.d <- deshape(cbind(tt, DF), id = 1:2) # same tt as above reshape(DF.d, ID ~ variable + tt)