从rpart包中的决策规则中提取信息 [英] Extracting Information from the Decision Rules in rpart package
问题描述
我需要从决策树中的规则中提取信息.我在R中使用rpart软件包.我在软件包中使用演示数据来解释我的要求:
I need to extract information from the rules in decision tree. I am using rpart package in R. I am using demo data in the package to explain my requirements:
data(stagec)
fit<- rpart(formula = pgstat ~ age + eet + g2 + grade + gleason + ploidy, data = stagec, method = "class", control=rpart.control(cp=0.05))
fit
打印适合的显示
n= 146
node), split, n, loss, yval, (yprob)
* denotes terminal node
1) root 146 54 0 (0.6301370 0.3698630)
2) grade< 2.5 61 9 0 (0.8524590 0.1475410) *
3) grade>=2.5 85 40 1 (0.4705882 0.5294118)
6) g2< 13.2 40 17 0 (0.5750000 0.4250000)
12) ploidy=diploid,tetraploid 31 11 0 (0.6451613 0.3548387) *
13) ploidy=aneuploid 9 3 1 (0.3333333 0.6666667) *
7) g2>=13.2 45 17 1 (0.3777778 0.6222222)
14) g2>=17.91 22 8 0 (0.6363636 0.3636364) *
15) g2< 17.91 23 3 1 (0.1304348 0.8695652) *
例如我想获得以下有关第12个节点的信息
e.g. I would like to get information something like below for the 12th node
如果等级> = 2.5且g2 <13.2和(二倍体,四倍体)中的倍性预测0类的置信度为65%.任何有关此的指示将非常有帮助.
If grade>=2.5 and g2< 13.2 and ploidy in (diploid,tetraploid) then class 0 is predicted with 65% confidence. Any pointers on this would be very helpful.
谢谢
推荐答案
rpart.plot 软件包版本3.0(2018年7月)具有功能 rpart.rules
用于为树生成一组规则.例如
The
rpart.plot
package version 3.0 (July 2018) has a function
rpart.rules
for generating a set of rules for a tree. For example
library(rpart.plot)
data(stagec)
fit <- rpart(formula = pgstat ~ ., data = stagec, method = "class", control=rpart.control(cp=0.05))
rpart.rules(fit)
给予
pgstat
0.15 when grade < 3
0.35 when grade >= 3 & g2 < 13 & ploidy is diploid or tetraploid
0.36 when grade >= 3 & g2 >= 18
0.67 when grade >= 3 & g2 < 13 & ploidy is aneuploid
0.87 when grade >= 3 & g2 is 13 to 18
还有
rpart.rules(fit, roundint=FALSE, clip.facs=TRUE)
给予
pgstat
0.15 when grade < 2.5
0.35 when grade >= 2.5 & g2 < 13 & diploid or tetraploid
0.36 when grade >= 2.5 & g2 >= 18
0.67 when grade >= 2.5 & g2 < 13 & aneuploid
0.87 when grade >= 2.5 & g2 is 13 to 18
有关更多示例,请参见 rpart.plot插图.
For more examples see Chapter 4 of the rpart.plot vignette.
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