On Apr 19, 2009, at 6:45 PM, Grześ wrote:


I have database write as .csv file.

The external sorage format is not likely to be relevant. What might be informative would be to produce the code that reads this file.

When I want to get sth from my database I get NULL, but I know that there is
sth!
For example:

data$ID
NULL
data$kod
NULL

but command like below is always recognize by R
data[2,3]
[1] '082'

Tell is what happens when you enter:

str(data)
class(data)

Perhaps the third column is not named "ID" or "kod" or the object is not a data.frame, but is rather a matrix.

--
David Winsemius


In my opinion this problem is also connect with my attempt to create a tree.
I always get errors.

t.tree0=rpart(ID~.,t.train)
Error in eval(expr, envir, enclos) : object "ID" not found

t.tree0=rpart(kod~.,t.train)
Error in eval(expr, envir, enclos) : object "kod" not found

What I should do to create my simple trees?
--
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT

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