Tidy evaluation programming and ggplot2

Question

Trying to write a relatively simple wrapper to produce some plots, but can not work out how to specify tidy evaluation of grouping variables specified as ... an

Answer 1

I'm not sure I understand the question. Does this satisfy the requirements?

library(ggplot2)
library(data.table)

your_plot <- function(df, select, color=NULL) {

  df <- as.data.table(df)[, mget(na.omit(c(select, color)))]

  ggplot(melt(df, color, select), aes_string(x=quote(value), color=color)) +
    geom_histogram(stat="count") +
    facet_wrap(~variable, scales="free", strip.position="bottom")

}

your_plot(dplyr::starwars, c("height", "mass"), "hair_color")

This uses melt to stack the select variables, with the color variable(s) repeated for each stack. It also uses aes_string, since aes(x=value, color=color) fails when color=NULL.