R help - Apr 2003 - Writing a function

Hi r lovers,

I have written the following  function
> ClearDeltaBis
function(Matrix){
for (i in 1:3)
                        {
                        for (j in 1:2)
                                {if (is.na(Matrix[i,j]))
NA->(Matrix[i,j+1])}
                        }
Matrix
}

it looks correct but when I try to implement it on the MatCor Matrix I get
this error message
> ClearDeltaBis(MatCor)
Error: couldn't find function "(<-"

I don't understand where does it come from since I have no string like
(<-
in my code


Thanks for any help that could be provided.





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On Mon, 28 Apr 2003 vincent.stoliaroff at socgen.com wrote:
> I have written the following  function
> 
> > ClearDeltaBis
> function(Matrix){
> for (i in 1:3)
>                         {
>                         for (j in 1:2)
>                                 {if (is.na(Matrix[i,j]))
> NA->(Matrix[i,j+1])}
>                         }
> Matrix
> }
> 
> it looks correct but when I try to implement it on the MatCor Matrix I get
> this error message
> 
> > ClearDeltaBis(MatCor)
> Error: couldn't find function "(<-"
> 
> I don't understand where does it come from since I have no string like
(<-
> in my code
You do, in the line

NA->(Matrix[i,j+1])

That's an unusual way of writing

(Matrix[i,j+1]) <- NA

and you have a set of parentheses there on the LHS of the assignment.
R is looking for a function "(<-" to implement this as

Matrix[i,j+1] <- "(<-"(NA)

You don't need (or want) the parentheses.

You might want to look up how functions on the LHS of assignments are 
supposed to work in R.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

vincent.stoliaroff at socgen.com wrote:
> Hi r lovers,
> 
> I have written the following  function
> 
> 
>>ClearDeltaBis
> 
> function(Matrix){
> for (i in 1:3)
>                         {
>                         for (j in 1:2)
>                                 {if (is.na(Matrix[i,j]))
> NA->(Matrix[i,j+1])}
>                         }
> Matrix
> }
> 
> it looks correct but when I try to implement it on the MatCor Matrix I get
> this error message
> 
> 
>>ClearDeltaBis(MatCor)
> 
> Error: couldn't find function "(<-"
> 
> I don't understand where does it come from since I have no string like
(<-
> in my code
> 
> 
> Thanks for any help that could be provided.
Hint:

   NA->(Matrix[i,j+1])

is syntactically almost the same as

   (Matrix[i,j+1]) <- NA

but the latter (without the brackets) is less confusing.

Uwe Ligges