R for loops and if statements, can't save output as vector

Question

Trying to replace output vector with string value of small, medium or large.

I am able to print out a string of 200 (1by1) vectors containing small/medium/large but not save that as a vector. What am I missing in the for loop?

output<- rep(NA, 200)  
size <- sample(1:5000, 200) 

myfun<- function(){ 
for (i in size) {   if (i < 300) {   print(output[i] <- "small")   }

else if (i >= 300 & i<3000) {   print(output[i] <- "medium") } 

else if (i>= 3000) {   print(output[i]<- "large")   } } } 

output<- myfun()