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Did you read the help page for 'outer'?
?outer
It says
'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.
I don't think your logl function is vectorized according to your summary
of what you did.
Pete Dorothy wrote:> 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=10^(-1))
> y=seq(0.1,0.5,by=10^(-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.
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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.
On 3/4/2008 5:41 PM, Bill.Venables at csiro.au wrote:> 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.What problems have you seen? Duncan Murdoch
No problems with it working. The main problem I have observed is unrealistic expectations. People write an *essentially* non-vectorized function and expect Vectorize to produce a version of it which will out-perform explicit loops every time. No magic bullets in this game. Bill. 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: Duncan Murdoch [mailto:murdoch at stats.uwo.ca] Sent: Wednesday, 5 March 2008 9:36 AM To: Venables, Bill (CMIS, Cleveland) Cc: r-help at r-project.org Subject: Re: [R] vector manipulations On 3/4/2008 5:41 PM, Bill.Venables at csiro.au wrote:> Your problem is that your function log1( , ) is not vectorized with > respect to its arguments. For a function to work in outer(...) itmust> 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 intoa> vectorized one, but the results are not always entirely satisfactoryin> my experience.What problems have you seen? Duncan Murdoch