In Hadley Wickham's ggplot2 book in chapter 10.3, he alludes to making plot functions. I want to make many similar plots that use faceting, but I cannot refer to a column. If all my references are in aesthetics then I can use aes_string and everything works. Facet_wrap seems not to have an analogue.
library(ggplot2)
data(iris)
This is the plot I want to functionalize.
pl.flower1 <- ggplot(data=iris,
aes_string(x='Sepal.Length', y='Sepal.Width', color='Petal.Length')) +
geom_point() +facet_wrap(~Species)
This works if I do not facet.
flowerPlot <- function(dat, sl, sw, pl, sp){
ggplot(data=dat, aes_string(x=sl, y=sw, color=pl)) + geom_point()
}
pl.flower2 <- flowerPlot(iris, sl='Sepal.Length', sw='Sepal.Width', pl='Petal.Length')
What should "sp" be two lines below? A formula, a string? Maybe the whole aproach is wrong.
flowerPlotWrap <- function(dat, sl, sw, pl, sp){
ggplot(data=dat, aes_string(x=sl, y=sw, color=pl)) + geom_point() +facet_wrap(sp)
}
pl.flower3 <- flowerPlotWrap(iris, sl='Sepal.Length', sw='Sepal.Width', pl='Petal.Length', sp= ?????)
In addition to an answer I would love pointer on how anyone approaches this problem?
facet_wrap
expects a formula as its first argument, so I'd just coerce it with as.formula
, and feed in my sp
as a string:
flowerPlotWrap <- function(dat, sl, sw, pl, sp){
ggplot(data=dat, aes_string(x=sl, y=sw, color=pl)) +
geom_point() +facet_wrap(as.formula(sp)) # note the as.formula
}
pl.flower3 <- flowerPlotWrap(iris, sl='Sepal.Length',
sw='Sepal.Width', pl='Petal.Length',
sp= '~Species')
Alternatively if my formula was always going to look like ~[columnname]
, I could just build that in to flowerPlotWrap
and pass in the column name:
flowerPlotWrap <- function(dat, sl, sw, pl, sp){
ggplot(data=dat, aes_string(x=sl, y=sw, color=pl)) +
geom_point() +facet_wrap(as.formula(sprintf('~%s',sp)))
}
pl.flower3 <- flowerPlotWrap(iris, sl='Sepal.Length',
sw='Sepal.Width', pl='Petal.Length',
sp= 'Species')
(kudos to the reproducible example in your question! If everyone asked questions as well as that they'd get answers much quicker).
?facet_wrap
it says facet_wrap(facets,...)
and facets: formula specifying variabls to facet by
- mathematical.coffee 2012-04-04 23:34
Your function worked fine for me unmodified if I just used sp='Species'
, i.e. the name of the variable you want to facet by.
flowerPlotWrap(iris, sl='Sepal.Length', sw='Sepal.Width', pl='Petal.Length', sp='Species')
Here are some alternatives using new features from ggplot2 V3.0.0
Using strings :
flowerPlot <- function(dat, sl, sw, pl, sp){
ggplot(data=dat, aes(x=!!ensym(sl), y=!!ensym(sw), color=!!ensym(pl))) +
geom_point() +
facet_wrap(eval(expr(~!!ensym(sp))))
}
flowerPlot(iris, sl='Sepal.Length', sw='Sepal.Width', pl='Petal.Length', sp = 'Species')
Using names :
flowerPlot2 <- function(dat, sl, sw, pl, sp){
ggplot(data=dat, aes(x=!!enquo(sl), y=!!enquo(sw), color=!!enquo(pl))) +
geom_point() +
facet_wrap(eval(expr(~!!enquo(sp))))
}
flowerPlot2(iris, sl= Sepal.Length, sw=Sepal.Width, pl=Petal.Length, sp = Species)