Pass variable columns with optional facets in a function via ggplot in R

Question

I am trying to figure out how to create multiple ggplots with one function, to avoid tedious copying and pasting. I do not want to have to change argument names in the funct

Answer 1

Using aes_string will allow you to pass character strings into your ggplot2 function, allowing you to programmatically change it more easily:

my.plot = function(x, y, data)
{
p=ggplot(data, aes_string(x=x, y=y))+geom_bar(stat="identity")
print(p)
}

my.plot(x="xVar", y="yVar", data=dataTest)

my.plot(x="xVar", y="zVar", data=dataTest)

Answer 2

What about using %+% to update the plots instead?

Example:

library(ggplot2)

### sample data ###
n=25
dataTest = data.frame(
  xVar=sample(1:3, n, replace=TRUE), 
  yVar = rnorm(n, 5, 2), 
  zVar=rnorm(n, 5, .5) )

p1 <- ggplot(data = dataTest, aes(x = xVar, y = yVar)) + 
  geom_bar(stat = "identity")

aes2 <- aes(x = xVar, y = zVar)

p2 <- p1 %+% aes2

p1:

p2:

EDIT

or as @sebastian-c mentioned, aes_string

plots <- function(x, y, data = dataTest) {
  p1 <- ggplot(data = data, aes_string(x = x, y = y)) + 
    geom_bar(stat = "identity")

  p1
}

plots('xVar','yVar')

plots('xVar','zVar')

EDIT 2: beat me to the punch :o

Answer 3

Using @sebastian-c's answer and other sources, I have a function that I think will work and I wanted to share it. I think I see @Henrik's solution, but it seems like more typing, as I have 4 groups, 4 'x' categories, and a third category related to time (year, quarters, months).

library(ggplot2)

### sample data ###
n=25
dataTest = data.frame(
  xVar=sample(1:3, n, replace=TRUE), 
  yVar = rnorm(n, 5, 2), 
  zVar=rnorm(n, 5, .5),
  brand=letters[1:5])

### function
my.plot = function(x, y, data, group=NULL)
{
  p=ggplot(data, aes_string(x=x, y=y, fill=group))+
    geom_bar(stat="identity")
  # make a facet if group is not null
  if(length(group)>0) {
    facets = facet_wrap(formula(paste("~", group)))
    p = p + facets
  }
  return(p)
}