Using 'IF' operator to check if a given value in a dataframe cell belongs to a 'SET' of values

Question

I have a data.frame with names of animals

x=data.frame(c("lion","tiger","cow","vulture","hyena","leopard","deer","gazzelle"))
colnames(x)=c('animal')

#create sets of animals based on the their diet

carnivore=c("lion","tiger","leopard")
herbivore=c("cow","deer","gazzelle")
omnivore=c("vulture","hyena")

x$diet=NA   ## Add a new column where I want to enter if the animal is one of herbivore, carnivore or omnivore based on the value in x$animal

for (i in 1:(nrow(x))) {
  if (x$animal[i] 'is a subset of' "Omnivore") {
    x$diet[i] = "Omnivore"
  } else if (x$animal[i] 'is a subset of' "Carnivore") {
    x$diet[i] = "Carnivore"
  } else if (x$animal[i] 'is a subset of' "Herbivore") {
    x$diet[i] = "Herbivore"
  }
}





    

I am not quite able to write the code equivalent of 'is a subset of' in R, which I believe must have a simple solution. Any help is much appreciated

Answer 1

Your existing code needs %in% operator:

for (i in 1:(nrow(x))) {
  if (x$animal[i] %in% omnivore) {
    x$diet[i] = "Omnivore"
  } else if (x$animal[i] %in% carnivore) {
    x$diet[i] = "Carnivore"
  } else if (x$animal[i] %in% herbivore) {
    x$diet[i] = "Herbivore"
  }
}

I prefer nested ifelse() instead of forloop + if{}else{}:

x$diet <- ifelse(x$animal %in% carnivore, "Carnivore",
                 ifelse(x$animal %in% herbivore, "Herbivore",
                        ifelse(x$animal %in% omnivore, "Omnivore", "Other")))
x
#     animal      diet
# 1     lion Carnivore
# 2    tiger Carnivore
# 3      cow Herbivore
# 4  vulture  Omnivore
# 5    hyena  Omnivore
# 6  leopard Carnivore
# 7     deer Herbivore
# 8 gazzelle Herbivore