utilities.md
In ggplot2: Create Elegant Data Visualisations Using the Grammar of Graphics

check_required_aesthetics() errors on missing

`test()` requires the following missing aesthetics: y.

`test()` requires the following missing aesthetics: x and y.

`test()` requires the following missing aesthetics: x or y.

`test()` requires the following missing aesthetics: fill and x or y.

remove_missing checks input

`na.rm` must be `TRUE` or `FALSE`, not an integer vector.

characters survive remove_missing

Removed 1 row containing non-finite outside the scale range.

tolower() and toupper() has been masked

Please use `to_lower_ascii()`, which works fine in all locales.

Please use `to_upper_ascii()`, which works fine in all locales.

parse_safe() checks input

`text` must be a character vector, not an integer vector.

width_cm() and height_cm() checks input

Don't know how to get width of <character> object

Don't know how to get height of <character> object

cut_*() checks its input and output

Insufficient data values to produce 10 bins.

Specify exactly one of `n` and `width`.

Only one of `boundary` and `center` may be specified.

summary method gives a nice summary

Code
  summary(p)
Output
  data: manufacturer, model, displ, year, cyl, trans, drv, cty, hwy, fl,
    class [234x11]
  mapping:  x = ~displ, y = ~hwy, colour = ~drv
  scales:   x, xmin, xmax, xend, xintercept, xmin_final, xmax_final, xlower, xmiddle, xupper, x0, colour 
  faceting:  ~year, ~cyl 
  -----------------------------------
  geom_point: na.rm = FALSE
  stat_identity: na.rm = FALSE
  position_identity