default values
On Wed, 12 Mar 2008, Dwayne Blind wrote:
Dear R users,
I wrote the following toy example to explain my problem :
a=0
f=function(x,y,z) {
if (a==0) x[1]+x[2]+y
if (a!=0) x[1]+x[2]+y+z
}
f(1:2,3)
I have not specified z and I get an error.
What was the error? It works for me (so I've no idea), and returns NULL, the value of the last expression (invisibly). I think you intended f <- function(x, y, z) if (a==0) x[1]+x[2]+y else x[1]+x[2]+y+z or f <- function(x, y, z) ifelse(a==0, x[1]+x[2]+y, x[1]+x[2]+y+z)
Although a=0, R seems to want to
know z because it's in the expression x[1]+x[2]+y+z.
So I tried to put a default value :
a=0
f=function(x,y,z=0) {
if (a==0) x[1]+x[2]+y
if (a!=0) x[1]+x[2]+y+z
}
f(1:2,3)
Why isn't it working ? Sometimes everything is fine even though a parameter
is not specified.
Thanks a lot.
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