CODEWITHSUNDEEP
rggplot2
Hariharan S
Hariharan S

Reputation: 165

A function I created to return a ggplot object returns an error

I created a function to return a ggplot object like below

uni_var<-function(df,col){
  return(ggplot(df,aes(col))+geom_bar())
}

When I called on the mtcars data frame 

uni_var(mtcars,cyl)

I get the below error

Error in FUN(X[[i]], ...) : object 'cyl' not found
In addition: Warning message:
In FUN(X[[i]], ...) : restarting interrupted promise evaluation

What is wrong with the my function ?

Upvotes: 2

Views: 333

Answers (2)

Claudiu Papasteri
Claudiu Papasteri

Reputation: 2609

Nothing wrong with it. Just do:

uni_var(mtcars, "cyl")

Is this what you are going for?

uni_var<-function(df, col){
  col <- eval(substitute(col), df)
 return(ggplot(df, aes(col)) + geom_bar())
}

uni_var(mtcars, cyl)

Upvotes: 1

Ramiro Magno
Ramiro Magno

Reputation: 3175

It might be useful to study why you need the quotes as exemplified in @claudiu-papasteri's answer. Search for non-standard evaluation in R. Take a look also at https://rlang.r-lib.org/index.html.

Try figure why this example works:

library(ggplot2)

uni_var<-function(df,col){
  col <- rlang::enquo(col)
  return(ggplot(df,aes(!!col))+geom_bar())
}

uni_var(mtcars, cyl)

Upvotes: 4

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