[R] scope of variables in R

[Sigbert Klinke]

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Hi,

A) you should give and return the variables through input/output
parameter of the functions, e.g.

pwtset <- function(n, inout) {
  if (n < 100){
    inout$ncof <- n
  } else {
    inout$ncof <- n -100
  }
  ...
  return(inout)
}

ford <- function(inout) {
  ...
  n     <- 104
  inout <- pwtset(n, inout)
  print(inout$ncof)
  ...
  return (inout)
}

inout <- list(ncof=0, ioff=0, joff=0, sig=0.0)
inout <- ford(inout)
...

B) If you really need access to the global variables then use "assign"
and "get"

pwtset <- function(n) {
  if (n < 100){
    ncof <- n
  } else {
    ncof <- n -100
  }
  assign ("ncof", ncof, envir=.GlobalEnv)
  ...
  return(inout)
}

ford <- function(inout) {
  ...
  n     <- 104
  inout <- pwtset(n, inout)
  ncof  <- get("ncof", envir=.GlobalEnv)
  print(ncof)
  ...
}

...
ford()
...

This programing style has a serious disadvantage: Debugging can become
very difficult, since the value of ncof in .GlobalEnv might not be what
you expect.

Yours sincerely

Sigbert
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