Reading levels of a factor in r

Question

I have a problem reading my variable in R. I have data set like this :

Cloumn 1   Cloumn2
Pos           S
Pos           M
Pos           H
Pos           S
Neg           M
Neg           H 
Neg           S
Neg           M

So the first column is a factor of 2 levels, and the second column is a factor of 3 levels. When I read the file in R it reads the variables as characters and when I assign the second variable to be a factor it gives me a factor of 5 levels , but I have only three levels, can you please help me with this?

Answer 1

How are you generating the factors? If they are being read in as characters, you will need to mutate them into factors with the as_factor() or as.factor() . This gives two levels for the first column and three for the second:

library(tidyverse)

data <- tribble(~Cloumn1,   ~Cloumn2,
  "Pos", "S",
  "Pos", "M",
  "Pos", "H",
  "Pos", "S",
  "Neg", "M",
  "Neg", "H",
  "Neg", "S",
  "Neg", "M")
    
data <- data %>% 
  mutate(across(.cols = everything(), forcats::as_factor))

data$Cloumn1
  [1] Pos Pos Pos Pos Neg Neg Neg Neg
  Levels: Pos Neg

data$Cloumn2
  [1] S M H S M H S M
  Levels: S M H