Sapply returning matrix instead of vector-CodePudding

I have a function

myfunction <- function(x,y){
      x y
}

and I want to pass x and y vectors to it and get a vector of their same length which is just the sum of their elements.

For some reason when I use

 sapply(x,myfunction,y)

I get a matrix instead of a vector. What am I doing wrong? Am I using the wrong function?

Example:

x = c(1,2,3,4) 
y = c(2,4,6,8)
sapply(x,myfunction,y)
>     [,1] [,2] [,3] [,4]
      [1,]    3    4    5    6
      [2,]    5    6    7    8
      [3,]    7    8    9   10
      [4,]    9   10   11   12

when my desired output is a vector (3,6,9,12).

CodePudding user response：

Arithmetic operations are vectorized, so the function can be applied directly

 myfunction(x, y)
[1]  3  6  9 12

With sapply, the X input argument is used by x thus, each element of x is looped while the y remains the whole vector, thus when we apply the function, it returns the output with the same length as 'y' for each element of 'x' and also as sapply use simplify = TRUE by default, it returns a matrix. If we need to use *apply function (and assuming the example is a simplified case), then we may need either mapply or Map which does loop over the corresponding elements of both inputs and apply the function on each element separately

mapply(myfunction, x, y)
[1]  3  6  9 12