[R] 2 questions

[Saket Joshi]

Hi all,

I am using R1.5.0 under Unix,

I have a couple of questions here.

1. My program is running out of memory. I am writing a program to grow a
list of trees using rpart() on a subset of a large dataset(5807x693) with
a different response for every tree. I saw that after each tree was
constucted, 116 MB of data was being added to the Vcells. I have no idea
what this data is. My dataset is 30MB large and each tree is 1.6 MB large.
Could someone tell me how to monitor what data is getting stored in the
Vcells?

2. This is related to the same program as above. When growing a tree I
used the expression:

fit <- rpart(formula= x[[34]] ~ ., data = x)

This does not give an error but does give an obviously wrong answer. But
when I rearranged the data.frame, x, so that the response variable comes in the
first column and all the other variables in the remaining columns and
tried using

fit <- rpart(x)

it worked perfectly i.e gave the correct tree.
Could someone tell me what to do if I want the 34th column of the
data.frame to be the response variable but dont want to use the column
names in the formula for growing the tree.

Thanks in advance.
-Saket.


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