问题
How to find a split and root node in a regression tree, I made a regression tree from multiple vectors now I have to extract root node of rpart of multiple vectors.file contains numeric value of multiple vectors A,B,C,D,E,F,G,H ex. A vector contains 4,3,6,7,2,4,5,...and so on similarly others B,C,D,E,F,G,H .so want to extract F (which is a root node in my case) as an output from this input an after creating a tree .thank you.sorry unable to put any image :(
Here's what I've done so far
log_data <- read.csv(file="C:\\Users\\AASHU\\Desktop\\CART\\syn.csv",
header=T, as.is=T)
library(rpart)
fit <- rpart(A ~ B+C+D+E+F+G+H, log_data)
# plot(fit)
plot(fit, compress=TRUE, branch=0)
text(fit, xpd = NA, cex = 0.7)
summary(fit)
Call:
rpart(formula = A ~ B + C + D + E + F + G + H, data = log_data)
n=52 (1 observation deleted due to missingness)
CP nsplit rel error xerror xstd
1 0.09798662 0 1.0000000 1.065250 0.1888568
2 0.09347624 1 0.9020134 1.198999 0.1842667
3 0.03632980 2 0.8085371 1.154558 0.1859743
4 0.02297130 3 0.7722073 1.254874 0.2029423
5 0.01000000 4 0.7492360 1.274024 0.2118272
Node number 1: 52 observations, complexity param=0.09798662
mean=4.403846, MSE=1.509985
left son=2 (7 obs) right son=3 (45 obs)
Primary splits:
F < 5.5 to the right, improve=0.09798662, (0 missing)
...........
Now I have to extract root node F(F>=5.5) from fit (regression tree) and its split,can anyone help me?.
回答1:
find the lables of that tree so that we can extract any of the vector
when the root node is character(ex.-A)
nodes<-labels(fit, digits=4, minlength=1L, pretty, collapse=TRUE)
root<-substr(nodes[2], 1, 1)
from the path we can extract the root node of a tree,below one is best to extract root node name by going through its second split which is nothing but an root node.
nodes<-labels(fit, digits=4, minlength=1L, pretty, collapse=TRUE)
path<-path.rpart(fit, node_no, pretty=0, print.it=FALSE)
path[[2]][1]
来源：https://stackoverflow.com/questions/13011496/splits-and-root-node-of-binary-decision-treecart