On 30/03/20 7:55 am, David wrote:
I’m trying to write a function that will add items to two vectors, and
then to create a third vector that is of the form 1, 2, 3, …, length of
one of the newly modified vectors. My problem is that what I’ve written
doesn’t seem to return any of those modifications. How can I get the
new values to be returned? Here’s the function below. I want to add a
value, stp, to the end of the stpos vector, a value mcp to the end of
the mcpos vector, and the to create that days vector. When I call this
function with numerical values for stp and mcp, and then ask to see
stpos, mcpos, and days, nothing has been changed. How can I fix this?
Here’s the function:
> addday <- function(stp,mcp,stpos,mcpos){stpos<-c(stpos,stp)
+ mcpos<-c(mcpos,mcp)
+ days<-c(1:length(stpos))}
You are probably thinking in terms of "macro languages" rather than in R
terms.
An R function returns, essentially, the last assigned value. So your
function will return the "days" vector; all else disappears into a black
hole in cyberspace.
Something like the following should do what you want:
addday <- function(stp,mcp,stpos,mcpos){
stpos<-c(stpos,stp)
mcpos<-c(mcpos,mcp)
days<-c(1:length(stpos))
rslt <- list(stpos=stpos,mcpos=mcpos,days=days)
rslt
}
As is so often said on this list, you would do well to spend some time
reading and inwardly digesting a basic R tutorial, such as "An
Introduction to R", readily available from the R web page (under "Manuals").
HTH
cheers,
Rolf Turner
--
Honorary Research Fellow
Department of Statistics
University of Auckland
Phone: +64-9-373-7599 ext. 88276
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