Create mutually exclusive dummy variables from categorical variable in R [duplicate]

Answer 1

If your data is

id <- c(1,1,1,1)
time <- c(1,2,3,4)
df <- data.frame(id,time)

you can try

time <- as.character(time)
unique.time <- as.character(unique(df$time))
# Create a dichotomous dummy-variable for each time
x <- sapply(unique.time, function(x)as.numeric(df$time == x))

or

time.f = factor(time)
dummies = model.matrix(~time.f)