Adding text to a ggplot bar plot by group within a function

Question

Given a dataset like this:

XX<-as.factor(c('P','P','P','R','R','R','F','F','F'))
YY<-c(2,3,6,3,5,3,2,3,4)
Facto<-c("A","B","C","A","B","C","A","B","C")
Text<-c("Z","Z","F","Z","H","Z","Z",'Z',"M")
MyData<-data.frame(XX,YY,Facto,Text)
rm(Facto)

My goal is to have a function to create a bar chart with text above each bar

MyBarPlot<-function(Data, ColName){
  dodger = position_dodge(width = 0.9)
  ggplot(Data, aes(x=XX, y=YY, fill=Facto))+
    geom_bar(stat="identity", color="black",position=position_dodge())+
    scale_fill_viridis(discrete = TRUE,option = "D",name=)+
    geom_text(aes(label=Text, group = ColName), position = dodger, col='red')+
    theme_minimal()
  
  
}

When I run the above function, the "fill=" argument works just fine, but the "group by" aspect for geom_text does not.

MyBarPlot(MyData,'Facto')

If I change the "group=" line in the function like this:

MyBarPlot<-function(Data, ColName){
      dodger = position_dodge(width = 0.9)
      ggplot(Data, aes(x=XX, y=YY, fill=Facto))+
        geom_bar(stat="identity", color="black",position=position_dodge())+
        scale_fill_viridis(discrete = TRUE,option = "D",name=)+
        geom_text(aes(label=Text, group = Facto), position = dodger, col='red')+
        theme_minimal()
      
      
    }

I get what I want, but I lose the ability to assign this variable within my function. Is there way I can assign the "group=" dynamically within my function call, just as I'm doing with the "fill=" argument?

It seems like your function is not currently using the ColName parameter anywhere. — Jon Spring
– Jon Spring, Commented Mar 31, 2021 at 22:33
Here is a good primer on the nonstandard evaluation aspects of using ggplot2 inside functions. I think one reason your function worked as it did is because you have the variables in you global environment that you likely couldn't expect the user of the function to have. — teunbrand
– teunbrand, Commented Mar 31, 2021 at 22:33

Jon Spring · Accepted Answer · 2021-03-31 22:35:26Z

2

Does this do what you want?

MyBarPlot<-function(Data, ColName){
  dodger = position_dodge(width = 0.9)
  ggplot(Data, aes(x=XX, y=YY, fill= {{ColName}}))+
    geom_bar(stat="identity", color="black",position=position_dodge())+
    viridis::scale_fill_viridis(discrete = TRUE,option = "D",name=)+
    geom_text(aes(label=Text), position = dodger, col='red')+
    theme_minimal()
}


MyBarPlot(MyData,Facto)

answered Mar 31, 2021 at 22:35

Jon Spring

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2 Comments

Vint Over a year ago

Thanks- I didn't realize including the "group by" command was what was causing the problem. Just dropping it as you suggest fixed it

gonzalez.ivan90 Dec 18, 2024 at 1:37

Also great for the fill= {{ColName}}

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