How to cumulatively multiply vector without using cumprod in r?

Question

I need to create a function cprod -> that takes a numeric vector as an argument and returns a cumulative vector of the same length. So, if I have cprod(c(1,2,3)), the returning vector should be c (1, 1 * 2, 1 * 2 * 3) = c (1, 2, 6).

Can this be done without cumprod? Maybe with prod or for-loop?

Answer 1

One option could be:

Reduce(`*`, x, accumulate = TRUE)

[1] 1 2 6

Answer 2

It doesn't use cumprod...

x <- c(1,2,3)
exp(cumsum(log(x)))

#> [1] 1 2 6

Answer 3

Try this with a loop:

#Code
v1 <- c(1,2,3)
#Empty vector
v2 <- numeric(length(v1))
#Loop
for(i in 1:length(v1))
{
  #Move around each element
  e1 <- v1[1:i]
  #Compute prod
  vp <- prod(e1)
  #Save
  v2[i] <- vp
}

Output:

v2
[1] 1 2 6