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

Answer 1

You can try the dummies library.

R Code:

# Creating the data frame
# id <- c(1,1,1,1)
# time <- c(1,2,3,4)
# data <- data.frame(id, time)

install.packages("dummies")
library(dummies)
data <- cbind(data, dummy(data$time))

Output:

  id time data1 data2 data3 data4
   1    1     1     0     0     0
   1    2     0     1     0     0
   1    3     0     0     1     0
   1    4     0     0     0     1

Further you can rename the newly added dummy variable headers to suit your needs

R Code:

# Rename column headers
colnames(data)[colnames(data)=="data1"] <- "time_dummy_1"
colnames(data)[colnames(data)=="data2"] <- "time_dummy_2"
colnames(data)[colnames(data)=="data3"] <- "time_dummy_3"
colnames(data)[colnames(data)=="data4"] <- "time_dummy_4"

Output:

  id time time_dummy_1 time_dummy_2 time_dummy_3 time_dummy_4
   1    1            1            0            0            0
   1    2            0            1            0            0
   1    3            0            0            1            0
   1    4            0            0            0            1

Hope this helps.

Answer 2

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)