[英]How should I plot a multi-split (non binary split) decision tree run from RWeka J48() function?
[英]Accessing individual results from decision tree function JRip (RWeka library)
我正在使用library(RWeka)並在數據集上運行JRip函數。 有人知道以編程方式訪問規則結果集的方法,以便我可以分別訪問每個規則嗎?
這是一個僅出於說明目的的示例:
> library(datasets)
> head(npk)
block N P K yield
1 1 0 1 1 49.5
2 1 1 1 0 62.8
3 1 0 0 0 46.8
4 1 1 0 1 57.0
5 2 1 0 0 59.8
6 2 1 1 1 58.5
> tree_rip <- JRip(block ~ ., data = npk)
> tree_rip
JRIP rules:
===========
(yield <= 48.8) => block=4 (5.0/2.0)
(yield <= 52) => block=5 (4.0/1.0)
=> block=3 (15.0/11.0)
Number of Rules : 3
我想以數據框/表的方式訪問結果。 最接近的是通過以下方式檢索單個Blob字符串:
> tree_rip$classifier
[1] "Java-Object{JRIP rules:\n===========\n\n(yield <= 48.8) => block=4 (5.0/2.0)\n(yield <= 52) => block=5 (4.0/1.0)\n => block=3 (15.0/11.0)\n\nNumber of Rules : 3\n}"
我需要一些可以讓我分別獲得每個結果的東西,就像我調用tree_rip
時顯示的tree_rip
,所以我不僅可以獲得找到的規則的長度,而且可以一一訪問它們。
至少是這樣的(但理想情況下,每行分別訪問每個結果變量):
[1] (yield <= 48.8) => block=4 (5.0/2.0)
[2] (yield <= 52) => block=5 (4.0/1.0)
...
謝謝!
作為R的非用戶與Java集成的用戶,這對我來說證明是非常困難的。 在查看了這些結果之后,無論如何要努力找出REPL如何產生您所看到的結果:
str(tree_rip)
# omitting about 15 lines of output
# - attr(*, "class")= chr [1:3] "JRip" "Weka_rules" "Weka_classifier"
getAnywhere(print.JRIP)
# no object named ‘print.JRIP’ was found
getAnywhere(print.Weka_rules)
# no object named ‘print.Weka_rules’ was found
help(pack="RWeka")
getAnywhere(print.Weka_classifier)
# this did succeed ... so I though `.jcall` should also succeed
.jcall(tree_rip$classifier, "S", "toString")
# Error: could not find function ".jcall"
RWeka:::.jcall(tree_rip$classifier, "S", "toString")
# Error in get(name, envir = asNamespace(pkg), inherits = FALSE) :
# object '.jcall' not found
...我發現需要加載pkg:rJava才能訪問.jcall function
。 顯然,這是不加載支持庫而僅附加支持庫的情況之一。 (類似於僅在加載pkg:lattice時[錯誤地]假定grid.text
應該可用。)因此,這將為您提供所需的字符串集:
library(rJava)
as.matrix(scan(text=.jcall(tree_rip$classifier, "S", "toString") ,sep="\n", what="") )[
-c(1:2, 6), ,drop=FALSE]
#------------
[,1]
[1,] "(yield <= 48.8) => block=4 (5.0/2.0)"
[2,] "(yield <= 52) => block=5 (4.0/1.0)"
[3,] " => block=3 (15.0/11.0)"
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