ggplot2 3.3.4

This is a larger patch release fixing a huge number of bugs and introduces a
small selection of feature refinements.

Features

• Alt-text can now be added to a plot using the alt label, i.e
  + labs(alt = ...). Currently this alt text is not automatically propagated,
  but we plan to integrate into Shiny, RMarkdown, and other tools in the future.
  (@thomasp85, #4477)

• Add support for the BrailleR package for creating descriptions of the plot
  when rendered (@thomasp85, #4459)

• coord_sf() now has an argument default_crs that specifies the coordinate
  reference system (CRS) for non-sf layers and scale/coord limits. This argument
  defaults to NULL, which means non-sf layers are assumed to be in projected
  coordinates, as in prior ggplot2 versions. Setting default_crs = sf::st_crs(4326)
  provides a simple way to interpret x and y positions as longitude and latitude,
  regardless of the CRS used by coord_sf(). Authors of extension packages
  implementing stat_sf()-like functionality are encouraged to look at the source
  code of stat_sf()'s compute_group() function to see how to provide scale-limit
  hints to coord_sf() (@clauswilke, #3659).

• ggsave() now uses ragg to render raster output if ragg is available. It also
  handles custom devices that sets a default unit (e.g. ragg::agg_png)
  correctly (@thomasp85, #4388)

• ggsave() now returns the saved file location invisibly (#3379, @eliocamp).

• The scale arguments limits, breaks, minor_breaks, labels, rescaler
  and oob now accept purrr style lambda notation (@teunbrand, #4427). The same
  is true for as_labeller() (and therefore also labeller())
  (@netique, #4188).

• Manual scales now allow named vectors passed to values to contain fewer
  elements than existing in the data. Elements not present in values will be set
  to NA (@thomasp85, #3451)

• Date and datetime position scales support out-of-bounds (oob) arguments to
  control how limits affect data outside those limits (@teunbrand, #4199).

Fixes

• Fix a bug that after_stat() and after_scale() cannot refer to aesthetics
  if it's specified in the plot-global mapping (@yutannihilation, #4260).

• Fix bug in annotate_logticks() that would cause an error when used together
  with coord_flip() (@thomasp85, #3954)

• Fix a bug in geom_abline() that resulted in intercept not being subjected
  to the transformation of the y scale (@thomasp85, #3741)

• Extent the range of the line created by geom_abline() so that line ending
  is not visible for large linewidths (@thomasp85, #4024)

• Fix bug in geom_dotplot() where dots would be positioned wrong with
  stackgroups = TRUE (@thomasp85, #1745)

• Fix calculation of confidence interval for locfit smoothing in geom_smooth()
  (@topepo, #3806)

• Fix bug in geom_text() where "outward" and "inward" justification for
  some angle values was reversed (@aphalo, #4169, #4447)

• ggsave() now sets the default background to match the fill value of the
  plot.background theme element (@karawoo, #4057)

• It is now deprecated to specify guides(<scale> = FALSE) or
  scale_*(guide = FALSE) to remove a guide. Please use
  guides(<scale> = "none") or scale_*(guide = "none") instead
  (@yutannihilation, #4094).

• Fix a bug in guide_bins() where keys would disappear if the guide was
  reversed (@thomasp85, #4210)

• Fix bug in guide_coloursteps() that would repeat the terminal bins if the
  breaks coincided with the limits of the scale (@thomasp85, #4019)

• Make sure that default labels from default mappings doesn't overwrite default
  labels from explicit mappings (@thomasp85, #2406)

• Fix bug in labeller() where parsing was turned off if .multiline = FALSE
  (@thomasp85, #4084)

• Make sure label_bquote() has access to the calling environment when
  evaluating the labels (@thomasp85, #4141)

• Fix a bug in the layer implementation that introduced a new state after the
  first render which could lead to a different look when rendered the second
  time (@thomasp85, #4204)

• Fix a bug in legend justification where justification was lost of the legend
  dimensions exceeded the available size (@thomasp85, #3635)

• Fix a bug in position_dodge2() where NA values in thee data would cause an
  error (@thomasp85, #2905)

• Make sure position_jitter() creates the same jittering independent of
  whether it is called by name or with constructor (@thomasp85, #2507)

• Fix a bug in position_jitter() where different jitters would be applied to
  different position aesthetics of the same axis (@thomasp85, #2941)

• Fix a bug in qplot() when supplying c(NA, NA) as axis limits
  (@thomasp85, #4027)

• Remove cross-inheritance of default discrete colour/fill scales and check the
  type and aesthetic of function output if type is a function
  (@thomasp85, #4149)

• Fix bug in scale_[x|y]_date() where custom breaks functions that resulted in
  fracional dates would get misaligned (@thomasp85, #3965)

• Fix bug in scale_[x|y]_datetime() where a specified timezone would be
  ignored by the scale (@thomasp85, #4007)

• Fix issue in sec_axis() that would throw warnings in the absence of any
  secondary breaks (@thomasp85, #4368)

• stat_bin()'s computed variable width is now documented (#3522).

• stat_count() now computes width based on the full dataset instead of per
  group (@thomasp85, #2047)

• Extended stat_ecdf() to calculate the cdf from either x or y instead from y
  only (@jgjl, #4005)

• Fix a bug in stat_summary_bin() where one more than the requested number of
  bins would be created (@thomasp85, #3824)

• Only drop groups in stat_ydensity() when there are fewer than two data
  points and throw a warning (@andrewwbutler, #4111).

• Fixed a bug in strip assembly when theme has strip.text = element_blank()
  and plots are faceted with multi-layered strips (@teunbrand, #4384).

• Using theme(aspect.ratio = ...) together with free space in facet_grid()
  now crrectly throws an error (@thomasp85, #3834)

• Fixed a bug in labeller() so that .default is passed to as_labeller()
  when labellers are specified by naming faceting variables. (@waltersom, #4031)

• Updated style for example code (@rjake, #4092)

• ggplot2 now requires R >= 3.3 (#4247).

• ggplot2 now uses rlang::check_installed() to check if a suggested package is
  installed, which will offer to install the package before continuing (#4375,
  @malcolmbarrett)

• Improved error with hint when piping a ggplot object into a facet function
  (#4379, @mitchelloharawild).