How to use a variable to specify column name in ggplot

Question

I have a ggplot command

ggplot( rates.by.groups, aes(x=name, y=rate, colour=majr, group=majr) )

inside a function. But I would like to be a

Answer 1

Another option (ggplot2 > 3.0.0) is to use the tidy evaluation pronoun .data to slice the chosen variable/column from the rates.by.groups data frame.

library(ggplot2)
theme_set(theme_classic(base_size = 14))

# created by @Moody_Mudskipper
rates.by.groups <- data.frame(
  name = LETTERS[1:3],
  rate = 1:3,
  mjr = LETTERS[c(4, 4, 5)],
  gender = c("M", "F", "F")
)

f1 <- function(df, column) {
  gg <- ggplot(df, 
         aes(x = name, 
             y = rate, 
             fill  = .data[[column]], 
             group = .data[[column]])) +
    geom_col() +
    labs(fill = column)
  return(gg)
}

plot_list <- lapply(list("gender", "mjr"), function(x){ f1(rates.by.groups, x) })
plot_list
#> [[1]]

#> 
#> [[2]]

# combine all plots
library(egg)
ggarrange(plots = plot_list,
          nrow = 2,
          labels = c('A)', 'B)'))

^{Created on 2019-04-04 by the reprex package (v0.2.1.9000)}