[R] Fwd: filter out many data.frames

[Uwe Ligges]

Christian Schulz wrote:
> Yes, i have recognized my stupid approach.
> Now it works but any help how i get
> the names in tList from the expand.grid combinaton's instead
> number from 1:64 would like great!
> 
> Thanks Christian
> 
> 
> 
> data <- expand.grid(class02 = c("A","B","C","D"), class04 = 
> c("A","B","C","D"),PREDICT = c("A","B","C","D"))
> tList  <- vector("list", numeric(length(data)))

No. I told you to use vector(nrow(data), mode = "list").
length(data) equal 3 in your case, and numeric(3) is 0, hence you get an 
empty list. But you want to get one intitialized with 64 elements!

Furthermore, I told you that there are better ideas than calling an 
object "data".


> tasign <- paste("tList[[n]]  <-   try(summary(dtree[dtree$class02 == 
> paste(data$class02[n]) & dtree$class04 == paste(data$class04[n]) & 
> dtree$PREDICT==paste(data$PREDICT[n]),]))")
> tasign <-  parse(text=tasign)[[1]]
>           
> for(n in 1:nrow(data)) {
>   TAsign <- do.call("substitute",list(tasign,list(n=n,X=as.name(n))))
>   eval(TAsign)
> }

So, why are you doing these complicated things?

Just using
     names(theList) <- apply(data, 1, paste, collapse="")
(you want to replace data by the corrected name) after your loop in your 
first version would be sufficient, if you are going to name the list 
elements....

Uwe Ligges


> 
> 
> 
> Am Sonntag, 16. Mai 2004 12:48 schrieb 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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