Function input used as string - r

Question

saving_ggplot <- function(name = 'default', plotname = last_plot()) {
image_name = paste(name, ".png", sep="")
ggsave(image_name, plot = plotname,
scale = 1,
dpi = 300, limitsize = TRUE)
}
This is my function which saves a ggplot. However, I for the life of me cannot figure out how to take the name argument as a string.
for example if someone runes saving_ggplot(FILENAME, PLOTNAME)
it will just say no object FILENAME. In python I can just capture it and use it as str(), but using as.character or toString in R still doesn't work.
Error:
saving_ggplot(weightvsageTEST, weightvsageplot)
Error in paste(name, ".png", sep = "") :
object 'weightvsageTEST' not found
Successful call using ggsave:
ggsave('weightvsage.png', plot = last_plot(),
scale = 1,
dpi = 300, limitsize = TRUE)

Answer 1

You can use substitute():
saving_ggplot <- function(name, plotname) {
image_name = paste0(substitute(name), ".png") # paste0 removes need for sep arg
ggsave(image_name, plot = plotname,
scale = 1,
dpi = 300, limitsize = TRUE)
}
saving_ggplot(foo, p) # saves foo.png
Alternately, if you want to stay within tidyverse quasiquotation syntax, use enexpr() instead:
enexpr(name) # instead of substitute(name)
Data:
N <- 100
df <- data.frame(x=rnorm(n=N), y=rnorm(n=N))
p <- ggplot(df, aes(x,y)) + geom_smooth()