Wrapper function for R with optional parameter

Question

I have the following wrapper function:

plot.histogram = function(x.var, y.var, pf) {
  ggplot(aes_string(x.var, y.var), data = pf) +
    geom_bar(stat="identity", color = "black", fill = "steelblue") 
}

The function works fine. However, sometimes I don't want to pass y.var and just use the default count on the y-axis. Thus, in that specific case, the chart shouldn't be a bar chart but a histogram. So depending on the absence of y.var, the function should automatically decide if it draws a bar chart or a histogram.

So, how can I make the parameter y.var optional and automatically have a histogram drawn if y.varis not given?

Reproducible example, please. And barplot != histogram, which do you want? — AkselA, Jun 11 '17 at 12:22
You're absolutely right. Edited it: The question distinguishes now between bar chart and histogram. I didn't add a reproducible example to keep it short for the reader. It was more a functional / logical issue. — Amir Rahbaran, Jun 11 '17 at 12:40

score 1 · Accepted Answer · answered Jun 11 '17 at 12:20

1

If you are set on keeping the current parameters, I would set the y.var to have an initial value of NA then just pass it on. After initially setting an object p you can simply pass the y.var parameter later on:

plot.histogram = function(x.var, y.var = NA, pf) {
  p = ggplot(aes_string(x.var), data = pf)
  if(is.na(y.var) == TRUE){
    p + geom_histogram()
  }  
  else{
    p + geom_bar(aes_string(y = y.var),stat="identity", color = "black", fill = "steelblue")
  }
}

answered Jun 11 '17 at 12:20

Scott Stoltzman

363
1
15

That was exactly what I needed. Thanks! – Amir Rahbaran Jun 11 '17 at 12:37
1

The `==True` is not needed when using is.na(). – Ted Mosby Jan 31 '18 at 23:39

Wrapper function for R with optional parameter

1 Answers1