[R] vector manipulations

Bill.Venables at csiro.au
2008-03-04T22:41:28Z

Your problem is that your function log1( , ) is not vectorized with
respect to its arguments.  For a function to work in outer(...) it must
accept vectors for its first two arguments and it must produce a
parallel vector of responses.

To quote the help information for outer:

"FUN is called with these two extended vectors as arguments. Therefore,
it must be a vectorized function (or the name of one), expecting at
least two arguments."

Sometimes Vectorize can be used to make a non-vectorized function into a
vectorized one, but the results are not always entirely satisfactory in
my experience.  See

?Vectorize


Bill Venables
CSIRO Laboratories
PO Box 120, Cleveland, 4163
AUSTRALIA
Office Phone (email preferred): +61 7 3826 7251
Fax (if absolutely necessary):  +61 7 3826 7304
Mobile:                         +61 4 8819 4402
Home Phone:                     +61 7 3286 7700
mailto:Bill.Venables at csiro.au
http://www.cmis.csiro.au/bill.venables/

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Pete Dorothy
Sent: Wednesday, 5 March 2008 3:38 AM
To: r-help at r-project.org
Subject: [R] vector manipulations

Hello,

I have simulated a set of data which i called "nir" (a vector).

I have created a function "logl" which calculates the log-likelihood.

logl is a function of 2 real parameters : "beta" and "zeta"
(of length
1).

This function works perfectly well when I try for example
"logl(0.1,0.2)"

Now if I try :

x <- seq(0.1, 0.5, by = 0.1)
y <- seq(0.1, 0.5, by = 0.1)
z <- outer(x, y, logl)"

I get an error.

The problem seems to be that inside "logl", the following expression
is
calculated : "sum( log( beta+(nir-1)*zeta )  )". So it is a vector
manipulation. The error tells me that "nir" is not the size of
"zeta".
Yet
usually it is no problem since "length(zeta)=1".

When I replace "sum( log( beta+(nir-1)*zeta ) )" by a loop, I get no
mistake. But I think it slows down the program.

Do you have an idea where the problem is ?

Thank you very much.

	[[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.