How to plot/visualize a C50 decision tree in R?

Question

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.

My C50 model is called credit_model

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

What is the equivalent in the C50 algorithm to plot?

Answer 1

Right now, there are none built in. I've been working on an adapter for the partykit package (e.g. as.party) but have not gotten very far.

Max

Answer 2

You can use the following routine, to directly convert the decision tree into GraphViz dot language (and then plot it with GraphViz - a previous installation of GraphViz (http://www.graphviz.org/) is required).

Edit: Version 2 included hereinafter, which is able to handle multi-branched trees (version 1 could handle trees with only two splits). Version 2.2 corrects a missing initialization.

Example calling within R:

library(C50)
data(churn)
treeModel <- C5.0(x = churnTrain[, -20], y = churnTrain$churn)
C5.0.graphviz(treeModel, 'C:\\mydotfile.txt')

Then from the operating system (OS, e.g. a Windows command prompt):

dot -Tpng 'C:\mydotfile.txt' > 'C:\mygraph.png'

You can then open the mygraph.png file as a PNG (bitmap) and use it in your application.

For further details, here's the original post: http://r-project-thanos.blogspot.de/2014/09/plot-c50-decision-trees-in-r.html

   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()
}

thanos