[R] variable names

[Luis Miguel Almeida da Silva]

It worked! thank you

	-----Original Message----- 
	From: Torsten Hothorn [mailto:hothorn at ci.tuwien.ac.at] 
	Sent: Tue 22/07/2003 15:16 
	To: Luis Miguel Almeida da Silva 
	Cc: r-help at stat.math.ethz.ch 
	Subject: RE: [R] variable names
	
	

	On Tue, 22 Jul 2003, Luis Miguel Almeida da Silva wrote:
	
	> I didn't noticed that fact. I've already found a way to do that
	> 
	> x <- 1:40
	> colnames(df.treino) <- paste("Ncp",x,sep=".")
	> 
	> and this generates names that I can relate with the variables. Thanks anyway
	> 
	> The problem is that I use rpart in a loop and the class labels are in the last column. For the above example I would "type"
	> 
	> rpart(Ncp.40~.,data=df.treino)
	> 
	> But in the next step of the loop I can have only 35 variables and the class labels would be at the Ncp.36. So I have to refresh the formula in rpart... and that is my problem
	>
	
	R> df.treino <- data.frame(matrix(rnorm(25), ncol=5))
	R> thisformula <- as.formula(paste(colnames(df.treino)[ncol(df.treino)],
	"~ ."))
	R> thisformula
	X5 ~ .
	R> rpart(thisformula, data = df.treino)
	n= 5
	
	node), split, n, deviance, yval
	      * denotes terminal node
	
	1) root 5 3.032904 -0.3392065 *
	
	Torsten
	
	
	>       -----Original Message-----
	>       From: Torsten Hothorn [mailto:hothorn at ci.tuwien.ac.at]
	>       Sent: Tue 22/07/2003 14:57
	>       To: Luis Miguel Almeida da Silva
	>       Cc: r-help at stat.math.ethz.ch
	>       Subject: Re: [R] variable names
	>      
	>      
	>
	>
	>       On Tue, 22 Jul 2003, Luis Miguel Almeida da Silva wrote:
	>      
	>       > Dear helpers
	>       >
	>       > I want to use rpart several times in a loop to build a classification tree. My problem is that rpart needs a formula as argument and for that the variables need to have names and this doesn't happen in my case. Every iteration in the loop has a different dataset with several variables (ex. 38 or more) and so I can't type the names by hand every time. Is there any function that generates names for variables in a dataframe. If so, how can I use then the argument
	>       >
	>      
	>       If your data is organised in a data.frame, (dummy) variable names are
	>       available by default:
	>      
	>       R> mydata <- data.frame(matrix(rnorm(25), ncol=5))
	>       R> mydata
	>                 X1          X2         X3         X4          X5
	>       1  1.3806313 -0.41827136  0.9591628 -1.3351038  0.02746110
	>       2  0.5114590 -1.34111439 -0.9617552 -0.8367088 -0.06913021
	>       3 -1.7508089 -0.49387076 -1.7597395  2.3899490 -0.15209650
	>       4 -1.6753809 -1.28381808 -1.0424903  0.1002998  0.27784949
	>       5 -0.2605535 -0.09035652 -2.5786418  1.0483400 -0.70445615
	>       R> rpart(X1 ~ ., data = mydata)
	>       n= 5
	>      
	>       node), split, n, deviance, yval
	>             * denotes terminal node
	>      
	>       1) root 5 7.463698 -0.3589306 *
	>      
	>       best,
	>      
	>       Torsten
	>      
	>       > rpart(classlabels~. ,.....)
	>       >
	>       > thanks
	>       >
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	>       >
	>       >
	>      
	>      
	>
	>