如何在R中绘制/可视化C50决策树？ [英] How to plot/visualize a C50 decision tree in R?

问题描述

我正在使用C50决策树算法。我能够构建树并获得摘要，但是无法弄清楚如何绘制或绘制树。

I am using the C50 decision tree algorithm. I am able to build the tree and get the summaries, but cannot figure out how to plot or viz the tree.

我的C50模型称为credit_model

My C50 model is called credit_model

在其他决策树程序包中，我通常使用诸如plot（credit_model ）。在rpart中，它是rpart.plot（credit_model）。

In other decision tree packages, I usually use something like plot(credit_model). In rpart it is rpart.plot(credit_model).

C50算法中要绘制的等价物是什么？

What is the equivalent in the C50 algorithm to plot?

推荐答案

这是您要查找的功能：

C5.0.graphviz <- function( C5.0.model, filename, fontname ='Arial',col.draw ='black',
                           col.font ='blue',col.conclusion ='lightpink',col.question = 'grey78',
                           shape.conclusion ='box3d',shape.question ='diamond', 
                           bool.substitute = 'None', prefix=FALSE, vertical=TRUE ) {

  library(cwhmisc)  
  library(stringr) 
  treeout <- C5.0.model$output
  treeout<- substr(treeout, cpos(treeout, 'Decision tree:', start=1)+14,nchar(treeout))
  treeout<- substr(treeout, 1,cpos(treeout, 'Evaluation on training data', start=1)-2)
  variables <- data.frame(matrix(nrow=500, ncol=4)) 
  names(variables) <- c('SYMBOL','TOKEN', 'TYPE' , 'QUERY') 
  connectors <- data.frame(matrix(nrow=500, ncol=3)) 
  names(connectors) <- c('TOKEN', 'START','END')
  theStack <- data.frame(matrix(nrow=500, ncol=1)) 
  names(theStack) <- c('ITEM')
  theStackIndex <- 1
  currentvar <- 1
  currentcon <- 1
  open_connection <- TRUE
  previousindent <- -1
  firstindent <- 4
  substitutes <- data.frame(None=c('= 0','= 1'), yesno=c('no','yes'),
                            truefalse=c('false', 'true'),TF=c('F','T'))
  dtreestring<-unlist( scan(text= treeout,   sep='\n', what =list('character'))) 

  for (linecount in c(1:length(dtreestring))) {
    lineindent<-0
    shortstring <- str_trim(dtreestring[linecount], side='left')
    leadingspaces <- nchar(dtreestring[linecount]) - nchar(shortstring)
    lineindent <- leadingspaces/4
    dtreestring[linecount]<-str_trim(dtreestring[linecount], side='left') 
    while (!is.na(cpos(dtreestring[linecount], ':   ', start=1)) ) {
      lineindent<-lineindent + 1 
      dtreestring[linecount]<-substr(dtreestring[linecount],
                                     ifelse(is.na(cpos(dtreestring[linecount], ':   ', start=1)), 1,
                                            cpos(dtreestring[linecount], ':   ', start=1)+4),
                                     nchar(dtreestring[linecount]) )
      shortstring <- str_trim(dtreestring[linecount], side='left')
      leadingspaces <- nchar(dtreestring[linecount]) - nchar(shortstring)
      lineindent <- lineindent + leadingspaces/4
      dtreestring[linecount]<-str_trim(dtreestring[linecount], side='left')  
    }
    if (!is.na(cpos(dtreestring[linecount], ':...', start=1)))
      lineindent<- lineindent +  1 
    dtreestring[linecount]<-substr(dtreestring[linecount],
                                   ifelse(is.na(cpos(dtreestring[linecount], ':...', start=1)), 1,
                                          cpos(dtreestring[linecount], ':...', start=1)+4),
                                   nchar(dtreestring[linecount]) )
    dtreestring[linecount]<-str_trim(dtreestring[linecount])
    stringlist <- strsplit(dtreestring[linecount],'\\:')
    stringpart <- strsplit(unlist(stringlist)[1],'\\s')
    if (open_connection==TRUE) { 
      variables[currentvar,'TOKEN'] <- unlist(stringpart)[1]
      variables[currentvar,'SYMBOL'] <- paste('node',as.character(currentvar), sep='')
      variables[currentvar,'TYPE'] <- shape.question
      variables[currentvar,'QUERY'] <- 1
      theStack[theStackIndex,'ITEM']<-variables[currentvar,'SYMBOL']
      theStack[theStackIndex,'INDENT'] <-firstindent 
      theStackIndex<-theStackIndex+1
      currentvar <- currentvar + 1
      if(currentvar>2) { 
        connectors[currentcon - 1,'END'] <- variables[currentvar - 1, 'SYMBOL']
      }
    }
    connectors[currentcon,'TOKEN'] <- paste(unlist(stringpart)[2],unlist(stringpart)[3])
    if (connectors[currentcon,'TOKEN']=='= 0') 
      connectors[currentcon,'TOKEN'] <- as.character(substitutes[1,bool.substitute])
    if (connectors[currentcon,'TOKEN']=='= 1') 
      connectors[currentcon,'TOKEN'] <- as.character(substitutes[2,bool.substitute])
    if (open_connection==TRUE) { 
      if (lineindent<previousindent) {
        theStackIndex <- theStackIndex-(( previousindent- lineindent)  +1 )
        currentsymbol <-theStack[theStackIndex,'ITEM']
      } else 
        currentsymbol <-variables[currentvar - 1,'SYMBOL']
    } else {  
      currentsymbol <-theStack[theStackIndex-((previousindent -lineindent ) +1    ),'ITEM']
      theStackIndex <- theStackIndex-(( previousindent- lineindent)    )
    }
    connectors[currentcon, 'START'] <- currentsymbol
    currentcon <- currentcon + 1
    open_connection <- TRUE 
    if (length(unlist(stringlist))==2) {
      stringpart2 <- strsplit(unlist(stringlist)[2],'\\s')
      variables[currentvar,'TOKEN']  <- paste(ifelse((prefix==FALSE),'','Class'), unlist(stringpart2)[2]) 
      variables[currentvar,'SYMBOL']  <- paste('node',as.character(currentvar), sep='')
      variables[currentvar,'TYPE']   <- shape.conclusion
      variables[currentvar,'QUERY']  <- 0
      currentvar <- currentvar + 1
      connectors[currentcon - 1,'END'] <- variables[currentvar - 1,'SYMBOL']
      open_connection <- FALSE
    }
    previousindent<-lineindent
  }
  runningstring <- paste('digraph g {', 'graph ', sep='\n')
  runningstring <- paste(runningstring, ' [rankdir="', sep='')
  runningstring <- paste(runningstring, ifelse(vertical==TRUE,'TB','LR'), sep='' )
  runningstring <- paste(runningstring, '"]', sep='')
  for (lines in c(1:(currentvar-1))) {
    runningline <- paste(variables[lines,'SYMBOL'], '[shape="')
    runningline <- paste(runningline,variables[lines,'TYPE'], sep='' )
    runningline <- paste(runningline,'" label ="', sep='' )
    runningline <- paste(runningline,variables[lines,'TOKEN'], sep='' )
    runningline <- paste(runningline,
                         '" style=filled fontcolor=', sep='')
    runningline <- paste(runningline, col.font)
    runningline <- paste(runningline,' color=' )
    runningline <- paste(runningline, col.draw)
    runningline <- paste(runningline,' fontname=')
    runningline <- paste(runningline, fontname)
    runningline <- paste(runningline,' fillcolor=')
    runningline <- paste(runningline,
                         ifelse(variables[lines,'QUERY']== 0 ,col.conclusion,col.question))
    runningline <- paste(runningline,'];')
    runningstring <- paste(runningstring, runningline , sep='\n')
  }
  for (lines in c(1:(currentcon-1)))  { 
    runningline <- paste (connectors[lines,'START'], '->')
    runningline <- paste (runningline, connectors[lines,'END'])
    runningline <- paste (runningline,'[label="')
    runningline <- paste (runningline,connectors[lines,'TOKEN'], sep='')
    runningline <- paste (runningline,'" fontname=', sep='')
    runningline <- paste (runningline, fontname)
    runningline <- paste (runningline,'];')
    runningstring <- paste(runningstring, runningline , sep='\n')
  }
  runningstring <- paste(runningstring,'}')
  cat(runningstring)
  sink(filename, split=TRUE)
  cat(runningstring)
  sink()
}

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