CODEWITHSUNDEEP
rinput
sdgaw erzswer
sdgaw erzswer

Reputation: 2382

Parsing R user input into plotting functions

I've been dealing with user input for various graphs. My main aim was to ask the user for an input and then parse this to a plotting function. I managed to do this for scatterplot, but not boxplot and barplot. This is my working example:

n<- function(){
    readline(prompt="enter x value to plot: ")
}

m<- function(){
    readline(prompt="enter y value to plot: ")
}

plotfun <- function(dat) {
    colx <- n()
    coly <- m()
    plot(dat[,colx], dat[,coly], main="Scatterplot", pch=20,xlab=[,colx] )      
}

But when I try something similar with boxplot for example:

plot2<-function(infile){
    a<-readline(prompt="which variable")
    barplot(table(infile$a))
}

or 

a<-readline(prompt="enter...")
Boxplot( ~ a, data=infile, id.method="y")

It doesn't work

Errors were something like: can't find the object, argument "infile" is missing, with no default.

Upvotes: 0

Views: 198

Answers (2)

MrFlick
MrFlick

Reputation: 206197

You cannot use "$" with character variable names. You must do the subsetting with [ as you did in the other cases

plot2<-function(infile){
    a<-readline(prompt="which variable")
    barplot(table(infile[,a]))
}

If your Boxplot function is the one from car, then 

a<-readline(prompt="enter...")
Boxplot(infile[,a], labels=rownames(infile), id.method="y")

Is the variable friendly equivalent. You can't use character variables in formulas either. They are taken as literal values.

Upvotes: 0

Robert Krzyzanowski
Robert Krzyzanowski

Reputation: 9344

What is infile?

plot2 <- function(){
  a <- readline(prompt = "which variable")
  barplot(table(a))
}

Upvotes: 1

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