Managing argument input value usage inside an R function

Question

My function foo is meant to compute a variable called d using one of its arguments: s, t, or f.

For example, if a user uses foo(n = 30:35, s = 1:2, t = 3:5, f = 7) I want foo to first compute d using t, then f, and then s. Thus, in the output, I expect 6 ds (i.e., 2 from t, 1 from f, and 2 from s).

I want the the first 2 ns be for t, the next n be for f, and the remaining ns be for s. Is there a way I can mange ns inside the function this way?

foo <- function(n, s = NULL, t = NULL, f = NULL){

d1 <- if(!is.null(t)) t + n else NULL
d2 <- if(!is.null(f)) f^2 + n else NULL

m <- if(!is.null(s)) s/2 + n else NULL
r <- if(!is.null(m)) m + 1 else NULL

d3 <- if(!is.null(m)) m + r else NULL

data.frame(d = c(d1, d2, d3))
}

 # Example of use:
 foo(n = 30:35, s = 1:2, t = 3:5, f = 7)

akrun · Accepted Answer · 2019-05-18 20:14:55Z

1

We can loop through the elements of 't', 'f', 's', add (+) with 'n' and get the output in a list

foo <- function(n, s = NULL, t = NULL, f = NULL){

      dts <-  if(!is.null(t)) sapply(t, `+`, n) else NULL
      dfs <- if(!is.null(f)) sapply(f^2, `+`,  n) else NULL

      ms <- if(!is.null(s)) sapply(s/2, `+`,  n) else NULL
      rs <- if(!is.null(ms)) ms + 1 else NULL

      dss <- if(!is.null(ms)) ms + rs else NULL

      list(t_out =dts, f_out = dfs, s_out = dss)
      }

 # Example of use:
foo(n = 30:35, s = 1:2, t = 3:5, f = 7)

edited May 18, 2019 at 20:14

answered May 18, 2019 at 19:56

akrun

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3 Comments

rnorouzian Over a year ago

Thanks, my real function is not going to use + I just used a simple example. But I think I can't achieve what I have in mind. Anyways, thank you so much.

akrun Over a year ago

@rnorouzian If it is a complicated funciton, use anonymous function call sapply(t, function(x) yourfunction(x, n))

rnorouzian Over a year ago

Arun, is This difficult to achieve?

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