CODEWITHSUNDEEP
rfunctionloops
eNTROPY
eNTROPY

Reputation: 11

Loop vector return in R

I'm writing a function that should calculate the following of a vector of numbers (1 - x)^2. However, my function returns zeros and I don't know why:

ban <- function(x){
  res <- vector(mode = "numeric", length(x))
  for(i in x) 
    { res[i] <- (1 - res[i])^2}
  return(res)
}

input: ban(c(0.5, 0.6)) gives output: [1] 0 0. Why is the output zeros?

Upvotes: 0

Views: 850

Answers (1)

kath
kath

Reputation: 7724

Your res-vector is initialized with zeros. You can see that with: 

vector(mode = "numeric", length = length(c(0.5, 0.6)))
# [1] 0 0

Further in your for-loop you loop over x and use this to access the entries in res. But your x-vector contains non-integer values so the access does not work: 

res <- c(1, 2)
res[0.5]
# numeric(0)

In R you can do calculations on vectors like that

x <- c(0.5, 0.6)

(1-x)^2
# [1] 0.25 0.16

so you don't need a for-loop here.

Upvotes: 2

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