descriptionMeta: "This post introduces the concept of 2d density chart and explains how to build it with R and ggplot2. 2d histograms, hexbin charts, 2d distributions and others are considered." ...

Note the column name, mpg, is unquoted. That feature hasn’t been handy, though, if you want to write your own R functions using the tidyverse. That’s because base R functions usually need quoted ...