So I'm trying to learn R and using a number of resources including a book called "Discovering Statistics using R" and a bunch of other cool eBooks.
I understand a great method in programming is the Euclid's Algorithm.
Implementing it in a loop can be achieved like this:
gcd(x,y) //assuming x is the largest value
//do
r = x%y;
x = y;
y = r;
//while r != 0;
return x;
After several searches on Google, SO and Youtube refreshing my memory of gcd algorithms, I wasn't able to find one that doesn't use a loop. Even recursive methods seem to use loops.
How can this be achieved in R without the use of loops or if statements?
Thanks in advance.
Using the statement "without loops or the if statement" literally, here is a recursive version that uses ifelse:
gcd <- function(x,y) {
r <- x%%y;
return(ifelse(r, gcd(y, r), y))
}
One might not expect it, but this is actually vectorized:
gcd(c(1000, 10), c(15, 10))
[1] 5 10
A solution using if would not handle vectors of length greater than 1.