Dear members of R-list, I need to reproduce the rules of a decision tree. For that I need to use the csplit information from the rpart.object. But I cannot uderstand the information because from my example I get:> rpart.tree$csplit[,1] [,2] [,3] [,4] [,5] [,6] [,7] [1,] 1 3 3 1 3 3 3 [2,] 2 3 3 1 2 2 2 [3,] 1 3 3 1 3 3 3 [4,] 2 3 3 1 2 2 2 [5,] 2 3 3 1 2 2 2 [6,] 2 1 3 2 3 1 1 [7,] 2 3 3 2 3 3 1 [8,] 2 3 3 1 2 2 2 [9,] 2 1 3 2 3 1 1 [10,] 2 1 3 3 2 2 2 [11,] 2 1 1 2 1 1 3 [12,] 2 3 3 1 2 2 2 [13,] 2 1 1 2 3 1 1 [14,] 2 3 3 1 2 2 2 [15,] 2 1 3 2 1 1 1 [16,] 2 3 1 1 2 2 2 [17,] 2 3 3 1 2 2 2 [18,] 2 1 3 2 1 3 1 [19,] 2 3 3 1 2 2 2 [20,] 2 1 3 2 1 3 3 [21,] 2 3 1 2 2 2 2 [22,] 2 1 3 2 1 1 1 I don't understand why I have 22 rows (my tree has 21 nodes including the root node) and 7 columns (I have four explanatory variables: two numerics and two factors; plus the numeric target variable) ?rpart.object it says: csplit: this will be present only if one of the split variables is a factor. There is one row for each such split, and column 'i -1' if this level of the factor goes to the left, '+1' if it goes to the right, and 0 if that level is not present at this node of the tree. For an ordered categorical variable all levels are marked as 'R/L', including levels that are not present. The values I got are quite different. Can some one give me information on how to deal with that? Thanks in advance? Joao Moreira
I send again this help message once previously was detected a virus. So, I
don't
know if the R-list receive it. The virus problem is solved. Sorry for that.
----- Forwarded message from jmoreira at fe.up.pt -----
Date: Tue, 20 Sep 2005 14:35:12 +0100
From: jmoreira at fe.up.pt
Reply-To: jmoreira at fe.up.pt
Subject: Interpretation of csplit from rpart.object
To: r-help at stat.math.ethz.ch
Dear members of R-list,
I need to reproduce the rules of a decision tree. For that I need to use the
csplit information from the rpart.object. But I cannot uderstand the
information because from my example I get:> rpart.tree$csplit
[,1] [,2] [,3] [,4] [,5] [,6] [,7]
[1,] 1 3 3 1 3 3 3
[2,] 2 3 3 1 2 2 2
[3,] 1 3 3 1 3 3 3
[4,] 2 3 3 1 2 2 2
[5,] 2 3 3 1 2 2 2
[6,] 2 1 3 2 3 1 1
[7,] 2 3 3 2 3 3 1
[8,] 2 3 3 1 2 2 2
[9,] 2 1 3 2 3 1 1
[10,] 2 1 3 3 2 2 2
[11,] 2 1 1 2 1 1 3
[12,] 2 3 3 1 2 2 2
[13,] 2 1 1 2 3 1 1
[14,] 2 3 3 1 2 2 2
[15,] 2 1 3 2 1 1 1
[16,] 2 3 1 1 2 2 2
[17,] 2 3 3 1 2 2 2
[18,] 2 1 3 2 1 3 1
[19,] 2 3 3 1 2 2 2
[20,] 2 1 3 2 1 3 3
[21,] 2 3 1 2 2 2 2
[22,] 2 1 3 2 1 1 1
I don't understand why I have 22 rows (my tree has 21 nodes including the
root
node) and 7 columns (I have four explanatory variables: two numerics and two
factors; plus the numeric target variable)
?rpart.object says:
csplit: this will be present only if one of the split variables is a
factor. There is one row for each such split, and column 'i
-1' if this level of the factor goes to the left, '+1' if it
goes to the right, and 0 if that level is not present at this
node of the tree. For an ordered categorical variable all
levels are marked as 'R/L', including levels that are not
present.
The values I got are quite different.
Can some one give me information on how to deal with that?
Thanks in advance?
Joao Moreira
----- End forwarded message -----