Custom function for multiplying all odd values in matrix

I am trying to code a function in R which takes one argument (matrix) and multiply all odd values in it by 0.618.

This is what I got so far, but it is my first time working with R matrixes and not sure how to replace values in for loop, or if it’s better to do it after multiplying numbers.

>Solution :

Try this:

mat <- matrix(sample(80), ncol = 10)

ifelse(mat %% 2 != 0, mat * 0.618, mat)

ifelse takes three arguments:

1. the condition (in your case that the number is divisible by 2)

2. the value to assign if the condition occurs

3. the value to be assigned if the condition does not occur