While loop for returning vector of Fibonacci numbers

[newt]

Hi,
I'd like to create a function fun(x) that returns a vector of Fibonacci numbers that are smaller or equal to x (assuming x is also a Fibonacci number). I've defined x as 21 so I would like to get back a vector containing numbers 1, 1, 2, 3, 5, 8, 13, 21. I've managed to write a code that looks like this:

> storage <- c()
> x <- 21
> storage[1] <- 1
> storage[2] <- 1
> fun <- function(x){
+ while(storage[2] <= x){
+ storage<-c(storage, storage[2])
+ temp <- storage[1] + storage[2]
+ storage[1] <- storage[2]
+ storage[2] <- temp
+ }
+ }

So I formed an empty vector and defined its first two values. Then, using while loop I tried to define the new vector and new values for storage[1] and [2] with a help of temporary (temp) variable. But the problem is that this code only gives me back a vector (1,1). What would be the easiest way to fix this? Thank you for your help!

[nirgrahamuk]

Advanced R is a great free book, for taking your R to the next level.
https://adv-r.hadley.nz/function-operators.html
Fibonnaci is used as an example of a function that can benefit from memoisation, even ignoring that though, the implementation is very elegant.

fib <- function(n) {
  if (n < 2) return(1)
  fib(n - 2) + fib(n - 1)
}

I see though that this doesn't directly answer your question as you asked for a vector and not simply the number. I'll get back to this when I have some time.

[nirgrahamuk]

 
 fib <- function(x){
   storage <- c()
   storage[[1]] <- 1
   storage[[2]] <- 1
   while(tail(storage,1) < x){
     next_val <- sum(tail(storage,2) )
      storage <- c(storage,next_val)
   }
   return(storage)
 }
 
result <- fib(21)

result
[1]  1  1  2  3  5  8 13 21 

edit note, i dropped the equal sign in the while loop condition so on checking and getting the tail value equal to the desired x the while loop wont run (before doing this it would have calculated the next value after 21

[newt]

Thank you so much! This was really helpful.

[nirgrahamuk]

you're welcome, head and tail are super useful functions. I often use them to peek at top and bottom rows of unfamiliar datasets.