Re: [R] simple coding question

2007-07-31 Thread Darin A. England
I know that some ICD9 codes contain letters, so I suspect that they are stored as "character". Here is a function that just pads zeros on to the end to make the string five characters long. format <- function(icd9) { len <- length(strsplit(icd9, "")[[1]]) pad <- "" if (num <- 5-len) pad

Re: [R] question regression trees

2007-02-28 Thread Darin A. England
Claudia, Can you send us the actual call you are making to rpart()? The call to plot() doesn't really help. Darin On Wed, Feb 28, 2007 at 11:53:45AM -0500, Wensui Liu wrote: > with seeing more code and output, i guess your tree fails to grow. > > On 2/28/07, Claudia Romero <[EMAIL PROTECTED]> wro

Re: [R] comparing random forests and classification trees

2007-01-30 Thread Darin A. England
Amy, I have also had this issue with randomForest, that is, you lose the ability to explain the classifier in a simple way to non-specialists (everyone can understand the single decision tree.) As far as comparing the accuracy of the two, I think that you are correct in comparing them by the actua

Re: [R] randomForest and missing data

2007-01-04 Thread Darin A. England
> If there is a way around that with randomForest, I'd be interested to > know too. > > Hugues Sicotte > > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Darin A. England > Sent: Thursday, January 04, 2007 3:

[R] randomForest and missing data

2007-01-04 Thread Darin A. England
Does anyone know a reason why, in principle, a call to randomForest cannot accept a data frame with missing predictor values? If each individual tree is built using CART, then it seems like this should be possible. (I understand that one may impute missing values using rfImpute or some other metho