I am trying to create a Collatz sequence with while loop in R. What am i doing wrong in this while loop here?

Question

I am trying to create a Collatz sequence with while loop in R.

vector <-  NULL
n <- 10
while (n != 1) {
  if (n %% 2 == 0) {
    n <- n / 2
  } else {
    n <- (n * 3) + 1
  }
  vector <- c(vector, cbind(n))
  print(vector)
}

After running the code, I got:

[1] 5
[1]  5 16
[1]  5 16  8
[1]  5 16  8  4
[1]  5 16  8  4  2
[1]  5 16  8  4  2  1

How do I do it such that it only shows the last row? What went wrong in my code? Thanks for any help on this.

Answer 1

You have several ways to deal with print(vector)

• add if condition before print(vector) , ie,

vector <-  NULL
n <- 10
while (n != 1) {
  if (n %% 2 == 0) {
    n <- n / 2
  } else {
    n <- (n * 3) + 1
  }
  vector <- c(vector, cbind(n))
  if (n==1)  print(vector)
}

• move it outside while loop, ie,

vector <-  NULL
n <- 10
while (n != 1) {
  if (n %% 2 == 0) {
    n <- n / 2
  } else {
    n <- (n * 3) + 1
  }
  vector <- c(vector, cbind(n))
}
print(vector)