[R] Fwd: filter out many data.frames

[Uwe Ligges]

Christian Schulz wrote:
>   X <- numeric(length(data.frame))
> before the loop maybe work, because
> my computer works and works !? 
> 
> christian
> 
> 
> ----------  Weitergeleitete Nachricht  ----------
> 
> Subject: filter out many data.frames
> Date: Sonntag, 16. Mai 2004 00:02
> From: Christian Schulz <ozric at web.de>
> To: r-help at stat.math.ethz.ch
> 
> Hi ,
> 
> i would like  filter out all combinations of a  data-mining result?
> How i have to declare X because in every loop step it have another lengths ?
> 
>   X <- numeric(length(i1,...,i64))  ?
> 
> Many thanks
> Christian
> 
> 
>  tres <- function(data.frame) {
> + data <- expand.grid(class02 = c("A","B","C","D"), class04 =
> c("A","B","C","D"),PREDICT = c("A","B","C","D"))
> +     for (i in 1:nrow(data)){
> +     X[i]<- dtree[dtree$class02 == paste(data$class02[i]) & dtree$class04 ==
> paste(data$class04[i]) & dtree$PREDICT==paste(data$PREDICT[i]),]
> +     }
> +     return(X[i])
> +     }


Eh. You really want to rewrite that code. It depends on objects 
available in its parent (or grand-parent) envrionment.
I don't see why you need all those calls to paste().
You do *not* want to call an argument data.frame nor any other object 
data, but you *do* want to use the arguments specified.

Now, if X is initialized with numeric(), X is a numeric (n x 1) vector. 
I think you need at least a matrix or better a list, if the subsetting 
stuff returns more or even less than one row.

For a list X use, e.g.,
  X <- vector(nrow(data), mode = "list")
just before the for loop.

Uwe Ligges


> 
>> tres(dtree)
> 
> 
> Error: Object "X" not found
> 
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