My questions is self-explained by the example, but in short: I would to dcast the data frame and add 1 and NA depending on the matched that are in the original data frame. I tried reshape2::dcast(cars~colour), but this is not the output I wanted.
in
> data.frame(cars=c("car1","car2","car4"), colour=c("red","blue","black"))
cars colour
1 car1 red
2 car2 blue
3 car4 black
out
car1 car2 car4
red 1 NA NA
blue NA 1 NA
black NA NA 1
You can try the base R table function here -
df <- data.frame(cars=c("car1","car2","car4"), colour=c("red","blue","black"))
tab <- table(df)
tab
# colour
#cars black blue red
# car1 0 0 1
# car2 0 1 0
# car4 1 0 0
To get it similar to your expected output you may adjust the code -
tab <- df |> rev() |> table() |> as.data.frame.matrix()
tab[tab == 0] <- NA
tab
# car1 car2 car4
#black NA NA 1
#blue NA 1 NA
#red 1 NA NA