Major new features

Subtitle and caption

Thanks to @hrbrmstr plots now have subtitles and captions, which can be set with the subtitle and caption arguments to ggtitle() and labs(). You can control their appearance with the theme settings plot.caption and plot.subtitle. The main plot title is now left-aligned to better work better with a subtitle. The caption is right-aligned (@hrbrmstr).

Stacking

position_stack() and position_fill() now sort the stacking order to match grouping order. This allows you to control the order through grouping, and ensures that the default legend matches the plot (#1552, #1593). If you want the opposite order (useful if you have horizontal bars and horizontal legend), you can request reverse stacking by using position = position_stack(reverse = TRUE) (#1837).

position_stack() and position_fill() now accepts negative values which will create stacks extending below the x-axis (#1691).

position_stack() and position_fill() gain a vjust argument which makes it easy to (e.g.) display labels in the middle of stacked bars (#1821).

Layers

geom_col() was added to complement geom_bar() (@hrbrmstr). It uses stat="identity" by default, making the y aesthetic mandatory. It does not support any other stat_() and does not provide fallback support for the binwidth parameter. Examples and references in other functions were updated to demonstrate geom_col() usage.

When creating a layer, ggplot2 will warn if you use an unknown aesthetic or an unknown parameter. Compared to the previous version, this is stricter for aesthetics (previously there was no message), and less strict for parameters (previously this threw an error) (#1585).

Facetting

The facet system, as well as the internal panel class, has been rewritten in ggproto. Facets are now extendable in the same manner as geoms and stats, as described in vignette("extending-ggplot2").

We have also added the following new fatures.

• facet_grid() and facet_wrap() now allow expressions in their facetting
  formulas (@DanRuderman, #1596).
• When facet_wrap() results in an uneven number of panels, axes will now be
  drawn underneath the hanging panels (fixes #1607)
• Strips can now be freely positioned in facet_wrap() using the
  strip.position argument (deprecates switch).
• The relative order of panel, strip, and axis can now be controlled with
  the theme setting strip.placement that takes either inside (strip between
  panel and axis) or outside (strip after axis).
• The theme option panel.margin has been deprecated in favour of
  panel.spacing to more clearly communicate intent.

Extensions

Unfortunately there was a major oversight in the construction of ggproto which lead to extensions capturing the super object at package build time, instead of at package run time (#1826). This problem has been fixed, but requires re-installation of all extension packages.

Scales

• The position of x and y axes can now be changed using the position argument
  in scale_x_*and scale_y_* which can take top and bottom, and left
  and right respectively. The themes of top and right axes can be modified
  using the .top and .right modifiers to axis.text.* and axis.title.*.

Continuous scales

• scale_x_continuous() and scale_y_continuous() can now display a secondary
  axis that is a one-to-one transformation of the primary axis (e.g. degrees
  Celcius to degrees Fahrenheit). The secondary axis will be positioned opposite
  to the primary axis and can be controlled with the sec.axis argument to
  the scale constructor.
• Scales worry less about having breaks. If no breaks can be computed, the
  plot will work instead of throwing an uninformative error (#791). This
  is particularly helpful when you have facets with free scales, and not
  all panels contain data.
• Scales now warn when transformation introduces infinite values (#1696).

Date time

• scale_*_datetime() now supports time zones. It will use the timezone
  attached to the varaible by default, but can be overridden with the
  timezone argument.
• New scale_x_time() and scale_y_time() generate reasonable default
  breaks and labels for hms vectors (#1752).

Discrete scales

The treatment of missing values by discrete scales has been thoroughly overhauled (#1584). The underlying principle is that we can naturally represent missing values on discrete variables (by treating just like another level), so by default we should.

This principle applies to:

• character vectors
• factors with implicit NA
• factors with explicit NA

And to all scales (both position and non-position.)

Compared to the previous version of ggplot2, there are three main changes:

1. scale_x_discrete() and scale_y_discrete() always show discrete NA,
   regardless of their source
2. If present, NAs are shown in discete legends.
3. All discrete scales gain a na.translate argument that allows you to
   control whether NAs are translated to something that can be visualised,
   or should be left as missing. Note that if you don't translate (i.e.
   na.translate = FALSE) the missing values will passed on to the layer,
   which will warning that it's dropping missing values. To suppress the
   warnings, you'll also need to add na.rm = TRUE to the layer call.

There were also a number of other smaller changes

• Correctly use scale expansion factors.
• Don't preserve space for dropped levels (#1638).
• Only issue one warning when when asking for too many levels (#1674).
• Unicode labels work better on Windows (#1827).
• Warn when used with only continuous data (#1589)

Themes

• The theme() constructor now has named arguments rather than ellipses. This
  should make autocomplete substantially more useful. The documentation
  (including exampes) has been considerably improved.
• Built-in themes are more visually homogeneous, and match theme_grey better.
  (@jiho, #1679)
• When computing the height of titles, ggplot2 now includes the height of the
  descenders (i.e. the bits of g and y that hang beneath the baseline). This
  improves the margins around titles, particularly the y axis label (#1712).
  I have also very slightly increased the inner margins of axis titles, and
  removed the outer margins.
• Theme element inheritance is now easier to work with as modification now
  overrides default element_blank elements (#1555, #1557, #1565, #1567)
• Horizontal legends (i.e. legends on the top or bottom) are horizontally
  aligned by default (#1842). Use legend.box = "vertical" to switch back
  to the previous behaviour.
• element_line() now takes an arrow argument to specify arrows at the end of
  lines (#1740)

There were a number of tweaks to the theme elements that control legends:

• legend.justification now controls appearance will plotting the legend
  outside of the plot area. For example, you can use
  theme(legend.justification = "top") to make the legend align with the
  top of the plot.
• panel.margin and legend.margin have been renamed to panel.spacing and
  legend.spacing respectively, to better communicate intent (they only
  affect spacing between legends and panels, not the margins around them)
• legend.margin now controls margin around individual legends.
• New legend.box.background, legend.box.spacing, and legend.box.margin
  control the background, spacing, and margin of the legend box (the region
  that contains all legends).

Bug fixes and minor improvements

• ggplot2 now imports tibble. This ensures that all built-in datasets print
  compactly even if you haven't explicitly loaded tibble or dplyr (#1677).
• Class of aesthetic mapping is preserved when adding aes() objects (#1624).
• +.gg now works for lists that include data frames.
• annotation_x() now works in the absense of global data (#1655)
• geom_*(show.legend = FALSE) now works for guide_colorbar.
• geom_boxplot() gains new outlier.alpha (@jonathan-g) and
  outlier.fill (@schloerke, #1787) parameters to control the alpha/fill of
  outlier points independently of the alpha of the boxes.
• position_jitter() (and hence geom_jitter()) now correctly computes
  the jitter width/jitter when supplied by the user (#1775, @has2k1).
• geom_contour() more clearly describes what inputs it needs (#1577).
• geom_curve() respects the lineend paramater (#1852).
• geom_histogram() and stat_bin() understand the breaks parameter once
  more. (#1665). The floating point adjustment for histogram bins is now
  actually used - it was previously inadvertently ignored (#1651).
• geom_violin() no longer transforms quantile lines with the alpha aesthetic
  (@mnbram, #1714). It no longer errors when quantiles are requested but data
  have zero range (#1687). When trim = FALSE it once again has a nice
  range that allows the density to reach zero (by extending the range 3
  bandwidths to either side of the data) (#1700).
• geom_dotplot() works better when facetting and binning on the y-axis.
  (#1618, @has2k1).
• geom_hexbin() once again supports ..density.. (@mikebirdgeneau, #1688).
• geom_step() gives useful warning if only one data point in layer (#1645).
• layer() gains new check.aes and check.param arguments. These allow
  geom/stat authors to optional suppress checks for known aesthetics/parameters.
  Currently this is used only in geom_blank() which powers expand_limits()
  (#1795).
• All stat_*() display a better error message when required aesthetics are
  missing.
• stat_bin() and stat_summary_hex() now accept length 1 binwidth (#1610)
• stat_density() gains new argument n, which is passed to underlying function
  stats::density ("number of equally spaced points at which the
  density is to be estimated"). (@hbuschme)
• stat_binhex() now again returns count rather than value (#1747)
• stat_ecdf() respects pad argument (#1646).
• stat_smooth() once again informs you about the method it has chosen.
  It also correctly calculates the size of the largest group within facets.
• x and y scales are now symmetric regarding the list of
  aesthetics they accept: xmin_final, xmax_final, xlower,
  xmiddle and xupper are now valid x aesthetics.
• Scale extensions can now override the make_title and make_sec_title
  methods to let the scale modify the axis/legend titles.

New features

• When mapping an aesthetic to a constant (e.g.
  geom_smooth(aes(colour = "loess")))), the default guide title is the name
  of the aesthetic (i.e. "colour"), not the value (i.e. "loess") (#1431).
• layer() now accepts a function as the data argument. The function will be
  applied to the data passed to the ggplot() function and must return a
  data.frame (#1527, @thomasp85). This is a more general version of the
  deprecated subset argument.
• theme_update() now uses the + operator instead of %+replace%, so that
  unspecified values will no longer be NULLed out. theme_replace()
  preserves the old behaviour if desired (@oneillkza, #1519).
• stat_bin() has been overhauled to use the same algorithm as ggvis, which
  has been considerably improved thanks to the advice of Randy Prium (@rpruim).
  This includes:
  • Better arguments and a better algorithm for determining the origin.
    You can now specify either boundary or the center of a bin.
    origin has been deprecated in favour of these arguments.
  • drop is deprecated in favour of pad, which adds extra 0-count bins
    at either end (needed for frequency polygons). geom_histogram() defaults
    to pad = FALSE which considerably improves the default limits for
    the histogram, especially when the bins are big (#1477).
  • The default algorithm does a (somewhat) better job at picking nice widths
    and origins across a wider range of input data.
  • bins = n now gives a histogram with n bins, not n + 1 (#1487).

Bug fixes

• All \donttest{} examples run.
• All geom_() and stat_() functions now have consistent argument order:
  data + mapping, then geom/stat/position, then ..., then specific arguments,
  then arguments common to all layers (#1305). This may break code if you were
  previously relying on partial name matching, but in the long-term should make
  ggplot2 easier to use. In particular, you can now set the n parameter
  in geom_density2d() without it partially matching na.rm (#1485).
• For geoms with both colour and fill, alpha once again only affects
  fill (Reverts #1371, #1523). This was causing problems for people.
• facet_wrap()/facet_grid() works with multiple empty panels of data
  (#1445).
• facet_wrap() correctly swaps nrow and ncol when facetting vertically
  (#1417).
• ggsave("x.svg") now uses svglite to produce the svg (#1432).
• geom_boxplot() now understands outlier.color (#1455).
• geom_path() knows that "solid" (not just 1) represents a solid line (#1534).
• geom_ribbon() preserves missing values so they correctly generate a
  gap in the ribbon (#1549).
• geom_tile() once again accepts width and height parameters (#1513).
  It uses draw_key_polygon() for better a legend, including a coloured
  outline (#1484).
• layer() now automatically adds a na.rm parameter if none is explicitly
  supplied.
• position_jitterdodge() now works on all possible dodge aesthetics,
  e.g. color, linetype etc. instead of only based on fill (@bleutner)
• position = "nudge" now works (although it doesn't do anything useful)
  (#1428).
• The default scale for columns of class "AsIs" is now "identity" (#1518).
• scale_*_discrete() has better defaults when used with purely continuous
  data (#1542).
• scale_size() warns when used with categorical data.
• scale_size(), scale_colour(), and scale_fill() gain date and date-time
  variants (#1526).
• stat_bin_hex() and stat_bin_summary() now use the same underlying
  algorithm so results are consistent (#1383). stat_bin_hex() now accepts
  a weight aesthetic. To be consistent with related stats, the output variable
  from stat_bin_hex() is now value instead of count.
• stat_density() gains a bw parameter which makes it easy to get consistent
  smoothing between facets (@jiho)
• stat-density-2d() no longer ignores the h parameter, and now accepts
  bins and binwidth parameters to control the number of contours
  (#1448, @has2k1).
• stat_ecdf() does a better job of adding padding to -Inf/Inf, and gains
  an argument pad to suppress the padding if not needed (#1467).
• stat_function() gains an xlim parameter (#1528). It once again works
  with discrete x values (#1509).
• stat_summary() preserves sorted x order which avoids artefacts when
  display results with geom_smooth() (#1520).
• All elements should now inherit correctly for all themes except theme_void().
  (@Katiedaisey, #1555)
• theme_void() was completely void of text but facets and legends still
  need labels. They are now visible (@jiho).
• You can once again set legend key and height width to unit arithmetic
  objects (like 2 * unit(1, "cm")) (#1437).
• Eliminate spurious warning if you have a layer with no data and no aesthetics
  (#1451).
• Removed a superfluous comma in theme-defaults.r code (@jschoeley)
• Fixed a compatibility issue with ggproto and R versions prior to 3.1.2.
  (#1444)

Major changes

• ggplot no longer throws an error if you your plot has no layers. Instead it
  automatically adds geom_blank() (#1246).

• New cut_width() is a convenient replacement for the verbose
  plyr::round_any(), with the additional benefit of offering finer
  control.

• New geom_count() is a convenient alias to stat_sum(). Use it when you
  have overlapping points on a scatterplot. stat_sum() now defaults to
  using counts instead of proportions.

• New geom_curve() adds curved lines, with a similar specification to
  geom_segment() (@veraanadi, #1088).

• Date and datetime scales now have date_breaks, date_minor_breaks and
  date_labels arguments so that you never need to use the long
  scales::date_breaks() or scales::date_format().

• geom_bar() now has it's own stat, distinct from stat_bin() which was
  also used by geom_histogram(). geom_bar() now uses stat_count()
  which counts values at each distinct value of x (i.e. it does not bin
  the data first). This can be useful when you want to show exactly which
  values are used in a continuous variable.

• geom_point() gains a stroke aesthetic which controls the border width of
  shapes 21-25 (#1133, @seysayux). size and stroke are additive so a point
  with size = 5 and stroke = 5 will have a diameter of 10mm. (#1142)

• New position_nudge() allows you to slightly offset labels (or other
  geoms) from their corresponding points (#1109).

• scale_size() now maps values to area, not radius. Use scale_radius()
  if you want the old behaviour (not recommended, except perhaps for lines).

• New stat_summary_bin() works like stat_summary() but on binned data.
  It's a generalisation of stat_bin() that can compute any aggregate,
  not just counts (#1274). Both default to mean_se() if no aggregation
  functions are supplied (#1386).

• Layers are now much stricter about their arguments - you will get an error
  if you've supplied an argument that isn't an aesthetic or a parameter.
  This is likely to cause some short-term pain but in the long-term it will make
  it much easier to spot spelling mistakes and other errors (#1293).

  This change does break a handful of geoms/stats that used ... to pass
  additional arguments on to the underlying computation. Now
  geom_smooth()/stat_smooth() and geom_quantile()/stat_quantile()
  use method.args instead (#1245, #1289); and stat_summary() (#1242),
  stat_summary_hex(), and stat_summary2d() use fun.args.

Extensibility

There is now an official mechanism for defining Stats, Geoms, and Positions in other packages. See vignette("extending-ggplot2") for details.

• All Geoms, Stats and Positions are now exported, so you can inherit from them
  when making your own objects (#989).
• ggplot2 no longer uses proto or reference classes. Instead, we now use
  ggproto, a new OO system designed specifically for ggplot2. Unlike proto
  and RC, ggproto supports clean cross-package inheritance. Creating a new OO
  system isn't usually the right way to solve a problem, but I'm pretty sure
  it was necessary here. Read more about it in the vignette.
• aes_() replaces aes_q(). It also supports formulas, so the most concise
  SE version of aes(carat, price) is now aes_(~carat, ~price). You may
  want to use this form in packages, as it will avoid spurious R CMD check
  warnings about undefined global variables.

Text

• geom_text() has been overhauled to make labelling your data a little
  easier. It:
  • nudge_x and nudge_y arguments let you offset labels from their
    corresponding points (#1120).
  • check_overlap = TRUE provides a simple way to avoid overplotting
    of labels: labels that would otherwise overlap are omitted (#1039).
  • hjust and vjust can now be character vectors: "left", "center",
    "right", "bottom", "middle", "top". New options include "inward" and
    "outward" which align text towards and away from the center of the plot
    respectively.
• geom_label() works like geom_text() but draws a rounded rectangle
  underneath each label (#1039). This is useful when you want to label plots
  that are dense with data.

Deprecated features

• The little used aes_auto() has been deprecated.
• aes_q() has been replaced with aes_() to be consistent with SE versions
  of NSE functions in other packages.
• The order aesthetic is officially deprecated. It never really worked, and
  was poorly documented.
• The stat and position arguments to qplot() have been deprecated.
  qplot() is designed for quick plots - if you need to specify position
  or stat, use ggplot() instead.
• The theme setting axis.ticks.margin has been deprecated: now use the margin
  property of axis.ticks.
• stat_abline(), stat_hline() and stat_vline() have been removed:
  these were never suitable for use other than with geom_abline() etc
  and were not documented.
• show_guide has been renamed to show.legend: this more accurately
  reflects what it does (controls appearance of layer in legend), and uses the
  same convention as other ggplot2 arguments (i.e. a . between names).
  (Yes, I know that's inconsistent with function names with use _, but it's
  too late to change now.)

A number of geoms have been renamed to be internally consistent:

• stat_binhex() and stat_bin2d() have been renamed to stat_bin_hex()
  and stat_bin_2d() (#1274). stat_summary2d() has been renamed to
  stat_summary_2d(), geom_density2d()/stat_density2d() has been renamed
  to geom_density_2d()/stat_density_2d().
• stat_spoke() is now geom_spoke() since I realised it's a
  reparameterisation of `geom_segment().
• stat_bindot() has been removed because it's so tightly coupled to
  geom_dotplot(). If you happened to use stat_bindot(), just change to
  geom_dotplot() (#1194).

All defunct functions have been removed.

Default appearance

• The default theme_grey() background colour has been changed from "grey90"
  to "grey92": this makes the background a little less visually prominent.

• Labels and titles have been tweaked for readability:

  • Axes labels are darker.
  • Legend and axis titles are given the same visual treatment.
  • The default font size dropped from 12 to 11. You might be surprised that
    I've made the default text size smaller as it was already hard for
    many people to read. It turns out there was a bug in RStudio (fixed in
    0.99.724), that shrunk the text of all grid based graphics. Once that
    was resolved the defaults seemed too big to my eyes.
  • More spacing between titles and borders.
  • Default margins scale with the theme font size, so the appearance at
    larger font sizes should be considerably improved (#1228).

• alpha now affects both fill and colour aesthetics (#1371).

• element_text() gains a margins argument which allows you to add additional
  padding around text elements. To help see what's going on use debug = TRUE
  to display the text region and anchors.

• The default font size in geom_text() has been decreased from 5mm (14 pts)
  to 3.8 mm (11 pts) to match the new default theme sizes.

• A diagonal line is no longer drawn on bar and rectangle legends. Instead, the
  border has been tweaked to be more visible, and more closely match the size of
  line drawn on the plot.

• geom_pointrange() and geom_linerange() get vertical (not horizontal)
  lines in the legend (#1389).

• The default line size for geom_smooth() has been increased from 0.5 to 1
  to make it easier to see when overlaid on data.

• geom_bar() and geom_rect() use a slightly paler shade of grey so they
  aren't so visually heavy.

• geom_boxplot() now colours outliers the same way as the boxes.

• geom_point() now uses shape 19 instead of 16. This looks much better on
  the default Linux graphics device. (It's very slightly smaller than the old
  point, but it shouldn't affect any graphics significantly)

• Sizes in ggplot2 are measured in mm. Previously they were converted to pts
  (for use in grid) by multiplying by 72 / 25.4. However, grid uses printer's
  points, not Adobe (big pts), so sizes are now correctly multiplied by
  72.27 / 25.4. This is unlikely to noticeably affect display, but it's
  technically correct (https://youtu.be/hou0lU8WMgo).

• The default legend will now allocate multiple rows (if vertical) or
  columns (if horizontal) in order to make a legend that is more likely to
  fit on the screen. You can override with the nrow/ncol arguments
  to guide_legend()

    p <- ggplot(mpg, aes(displ,hwy, colour = model)) + geom_point()
    p
    p + theme(legend.position = "bottom")
    # Previous behaviour
    p + guides(colour = guide_legend(ncol = 1))

New and updated themes

• New theme_void() is completely empty. It's useful for plots with non-
  standard coordinates or for drawings (@jiho, #976).
• New theme_dark() has a dark background designed to make colours pop out
  (@jiho, #1018)
• theme_minimal() became slightly more minimal by removing the axis ticks:
  labels now line up directly beneath grid lines (@tomschloss, #1084)
• New theme setting panel.ontop (logical) make it possible to place
  background elements (i.e., gridlines) on top of data. Best used with
  transparent panel.background (@noamross. #551).

Labelling

The facet labelling system was updated with many new features and a
more flexible interface (@lionel-). It now works consistently across
grid and wrap facets. The most important user visible changes are:

• facet_wrap() gains a labeller option (#25).
• facet_grid() and facet_wrap() gain a switch argument to
  display the facet titles near the axes. When switched, the labels
  become axes subtitles. switch can be set to "x", "y" or "both"
  (the latter only for grids) to control which margin is switched.

The labellers (such as label_value() or label_both()) also get
some new features:

• They now offer the multi_line argument to control whether to
  display composite facets (those specified as ~var1 + var2) on one
  or multiple lines.

• In label_bquote() you now refer directly to the names of
  variables. With this change, you can create math expressions that
  depend on more than one variable. This math expression can be
  specified either for the rows or the columns and you can also
  provide different expressions to each margin.

  As a consequence of these changes, referring to x in backquoted
  expressions is deprecated.

• Similarly to label_bquote(), labeller() now take .rows and
  .cols arguments. In addition, it also takes .default.
  labeller() is useful to customise how particular variables are
  labelled. The three additional arguments specify how to label the
  variables are not specifically mentioned, respectively for rows,
  columns or both. This makes it especially easy to set up a
  project-wide labeller dispatcher that can be reused across all your
  plots. See the documentation for an example.

• The new labeller label_context() adapts to the number of factors
  facetted over. With a single factor, it displays only the values,
  just as before. But with multiple factors in a composite margin
  (e.g. with ~cyl + am), the labels are passed over to
  label_both(). This way the variables names are displayed with the
  values to help identifying them.

On the programming side, the labeller API has been rewritten in order
to offer more control when facetting over multiple factors (e.g. with
formulae such as ~cyl + am). This also means that if you have
written custom labellers, you will need to update them for this
version of ggplot.

• Previously, a labeller function would take variable and value
  arguments and return a character vector. Now, they take a data frame
  of character vectors and return a list. The input data frame has one
  column per factor facetted over and each column in the returned list
  becomes one line in the strip label. See documentation for more
  details.
• The labels received by a labeller now contain metadata: their margin
  (in the "type" attribute) and whether they come from a wrap or a
  grid facet (in the "facet" attribute).
• Note that the new as_labeller() function operator provides an easy
  way to transform an existing function to a labeller function. The
  existing function just needs to take and return a character vector.

Documentation

• Improved documentation for aes(), layer() and much much more.
• I've tried to reduce the use of ... so that you can see all the
  documentation in one place rather than having to integrate multiple pages.
  In some cases this has involved adding additional arguments to geoms
  to make it more clear what you can do:
  • geom_smooth() gains explicit method, se and formula arguments.
  • geom_histogram() gains binwidth, bins, originandright`
    arguments.
  • geom_jitter() gains width and height arguments to make it easier
    to control the amount of jittering without using the lengthy
    position_jitter() function (#1116)
• Use of qplot() in examples has been minimised (#1123, @hrbrmstr). This is
  inline with the 2nd edition of the ggplot2 box, which minimises the use of
  qplot() in favour of ggplot().
• Tighly linked geoms and stats (e.g. geom_boxplot() and stat_boxplot())
  are now documented in the same file so you can see all the arguments in one
  place. Variations of the same idea (e.g. geom_path(), geom_line(), and
  geom_step()) are also documented together.
• It's now obvious that you can set the binwidth parameter for
  stat_bin_hex(), stat_summary_hex(), stat_bin_2d(), and
  stat_summary_2d().
• The internals of positions have been cleaned up considerably. You're unlikely
  to notice any external changes, although the documentation should be a little
  less confusing since positions now don't list parameters they never use.

Data

• All datasets have class tbl_df so if you also use dplyr, you get a better
  print method.
• economics has been brought up to date to 2015-04-01.
• New economics_long is the economics data in long form.
• New txhousing dataset containing information about the Texas housing
  market. Useful for examples that need multiple time series, and for
  demonstrating model+vis methods.
• New luv_colours dataset which contains the locations of all
  built-in colors() in Luv space.
• movies has been moved into its own package, ggplot2movies, because it was
  large and not terribly useful. If you've used the movies dataset, you'll now
  need to explicitly load the package with library(ggplot2movies).

Bug fixes and minor improvements

• All partially matched arguments and $ have been been replaced with
  full matches (@jimhester, #1134).
• ggplot2 now exports alpha() from the scales package (#1107), and arrow()
  and unit() from grid (#1225). This means you don't need attach scales/grid
  or do scales::/grid:: for these commonly used functions.
• aes_string() now only parses character inputs. This fixes bugs when
  using it with numbers and non default OutDec settings (#1045).
• annotation_custom() automatically adds a unique id to each grob name,
  making it easier to plot multiple grobs with the same name (e.g. grobs of
  ggplot2 graphics) in the same plot (#1256).
• borders() now accepts xlim and ylim arguments for specifying the geographical
  region of interest (@markpayneatwork, #1392).
• coord_cartesian() applies the same expansion factor to limits as for scales.
  You can suppress with expand = FALSE (#1207).
• coord_trans() now works when breaks are suppressed (#1422).
• cut_number() gives error message if the number of requested bins can
  be created because there are two few unique values (#1046).
• Character labels in facet_grid() are no longer (incorrectly) coerced into
  factors. This caused problems with custom label functions (#1070).
• facet_wrap() and facet_grid() now allow you to use non-standard
  variable names by surrounding them with backticks (#1067).
• facet_wrap() more carefully checks its nrow and ncol arguments
  to ensure that they're specified correctly (@richierocks, #962)
• facet_wrap() gains a dir argument to control the direction the
  panels are wrapped in. The default is "h" for horizontal. Use "v" for
  vertical layout (#1260).
• geom_abline(), geom_hline() and geom_vline() have been rewritten to
  have simpler behaviour and be more consistent:
  • stat_abline(), stat_hline() and stat_vline() have been removed:
    these were never suitable for use other than with geom_abline() etc
    and were not documented.
  • geom_abline(), geom_vline() and geom_hline() are bound to
    stat_identity() and position_identity()
  • Intercept parameters can no longer be set to a function.
  • They are all documented in one file, since they are so closely related.
• geom_bin2d() will now let you specify one dimension's breaks exactly,
  without touching the other dimension's default breaks at all (#1126).
• geom_crossbar() sets grouping correctly so you can display multiple
  crossbars on one plot. It also makes the default fatten argument a little
  bigger to make the middle line more obvious (#1125).
• geom_histogram() and geom_smooth() now only inform you about the
  default values once per layer, rather than once per panel (#1220).
• geom_pointrange() gains fatten argument so you can control the
  size of the point relative to the size of the line.
• geom_segment() annotations were not transforming with scales
  (@BrianDiggs, #859).
• geom_smooth() is no longer so chatty. If you want to know what the deafult
  smoothing method is, look it up in the documentation! (#1247)
• geom_violin() now has the ability to draw quantile lines (@DanRuderman).
• ggplot() now captures the parent frame to use for evaluation,
  rather than always defaulting to the global environment. This should
  make ggplot more suitable to use in more situations (e.g. with knitr)
• ggsave() has been simplified a little to make it easier to maintain.
  It no longer checks that you're printing a ggplot2 object (so now also
  works with any grid grob) (#970), and always requires a filename.
  Parameter device now supports character argument to specify which supported
  device to use ('pdf', 'png', 'jpeg', etc.), for when it cannot be correctly
  inferred from the file extension (for example when a temporary filename is
  supplied server side in shiny apps) (@sebkopf, #939). It no longer opens
  a graphics device if one isn't already open - this is annoying when you're
  running from a script (#1326).
• guide_colorbar() creates correct legend if only one color (@krlmlr, #943).
• guide_colorbar() no longer fails when the legend is empty - previously
  this often masked misspecifications elsewhere in the plot (#967).
• New layer_data() function extracts the data used for plotting for a given
  layer. It's mostly useful for testing.
• User supplied minor_breaks can now be supplied on the same scale as
  the data, and will be automatically transformed with by scale (#1385).
• You can now suppress the appearance of an axis/legend title (and the space
  that would allocated for it) with NULL in the scale_ function. To
  use the default lable, use waiver() (#1145).
• Position adjustments no longer warn about potentially varying ranges
  because the problem rarely occurs in practice and there are currently a
  lot of false positives since I don't understand exactly what FP criteria
  I should be testing.
• scale_fill_grey() now uses red for missing values. This matches
  scale_colour_grey() and makes it obvious where missing values lie.
  Override with na.value.
• scale_*_gradient2() defaults to using Lab colour space.
• scale_*_gradientn() now allows colours or colors (#1290)
• scale_y_continuous() now also transforms the lower, middle and upper
  aesthetics used by geom_boxplot(): this only affects
  geom_boxplot(stat = "identity") (#1020).
• Legends no longer inherit aesthetics if inherit.aes is FALSE (#1267).
• lims() makes it easy to set the limits of any axis (#1138).
• labels = NULL now works with guide_legend() and guide_colorbar().
  (#1175, #1183).
• override.aes now works with American aesthetic spelling, e.g. color
• Scales no longer round data points to improve performance of colour
  palettes. Instead the scales package now uses a much faster colour
  interpolation algorithm (#1022).
• scale_*_brewer() and scale_*_distiller() add new direction argument of
  scales::brewer_pal, making it easier to change the order of colours
  (@jiho, #1139).
• scale_x_date() now clips dates outside the limits in the same way as
  scale_x_continuous() (#1090).
• stat_bin() gains bins arguments, which denotes the number of bins. Now
  you can set bins=100 instead of binwidth=0.5. Note that breaks or
  binwidth will override it (@tmshn, #1158, #102).
• stat_boxplot() warns if a continuous variable is used for the x aesthetic
  without also supplying a group aesthetic (#992, @krlmlr).
• stat_summary_2d() and stat_bin_2d() now share exactly the same code for
  determining breaks from bins, binwidth, and origin.
• stat_summary_2d() and stat_bin_2d() now output in tile/raster compatible
  form instead of rect compatible form.
• Automatically computed breaks do not lead to an error for transformations like
  "probit" where the inverse can map to infinity (#871, @krlmlr)
• stat_function() now always evaluates the function on the original scale.
  Previously it computed the function on transformed scales, giving incorrect
  values (@BrianDiggs, #1011).
• strip_dots works with anonymous functions within calculated aesthetics
  (e.g. aes(sapply(..density.., function(x) mean(x)))) (#1154, @NikNakk)
• theme() gains validate = FALSE parameter to turn off validation, and
  hence store arbitrary additional data in the themes. (@tdhock, #1121)
• Improved the calculation of segments needed to draw the curve representing
  a line when plotted in polar coordinates. In some cases, the last segment
  of a multi-segment line was not drawn (@BrianDiggs, #952)

• Fixes to pass R CMD check --run-donttest in R-devel.

New features

• New coordinate system for small scale maps. coord_quickmap() computes and
  sets the correct aspect ratio between one degree of latitude and one degree
  of longitude at the centre of the plotted region. It does not perform full
  fledged mapping projection as coord_map() does and therefore is much
  faster. Yet, it gives a correct approximation for small scale maps (a few
  degrees in either direction) at medium to low latitudes (@jiho, #922).
• geom_boxplot gain new varwidth argument for controlling whether or not
  the width of boxplots should be proportional to the size of the groups
  (@tsieger, #927).
• position_jitterdodge() combines position_jitter() and position_dodge(),
  allowing the user to plot and align points generated by e.g. geom_point()
  with those generated by a dodged geom_boxplot(). See
  example(position_jitterdodge) for a potential usage. (@kevinushey, #932)
• Allow specifying only one of the limits in a scale and use the automatic
  calculation of the other limit by passing NA to to the limit function,
  xlim() or ylim() (@jimhester, #557).
• Allow to use brewer palettes for continuous scales, through the new
  scale_fill/colour_distiller() functions (@jiho, #925).
• stat_ellipse() adds data ellipses. It supports bivariate normal and t distributions,
  as well as a euclidian distance circle. (@JoFrhwld, #926)
• Add new themes: theme_linedraw() is similar to theme_bw() but with
  truly only white and black elements and spacing between elements identical
  to theme_gray. theme_light is similar but with light gray box and axes
  around the plot, to emphasise content more (@jiho, #923)
• new theme settings panel.margin.x and panel.margin.y (units) allow
  specifying horizontal and vertical gap between panels in facetted plots (for
  both grid and wrap). (Kirill Müller. Fixes #839)
• Fix vertical justification for rotated text. This will change the appearance
  of plots that use textual elements that are rotated by 90° or 270° and have a
  vjust parameter other than the default 0.5; the interpretation of vjust
  and hjust is now the same for both rotated and non-rotated text elements
  (0 = top/left, 1 = bottom/right, 0.5 = centered). (@krlmlr, #883)
• Added helper function labeller() for formatting faceting values.
  (@stefanedwards, #910). Added label_wrap_gen based on
  https://github.com/hadley/ggplot2/wiki/labeller#writing-new-labellers
  (@stefanedwards, #910)

Bug fixes and minor improvements

• aes() no more treats variables like `a..x..b as a calculated aesthetic.
  (@krlmlr, #834.)
• New aes_q() function to generate aesthetic specifications from
  quoted calls/names. aes_string() uses names x and y for first
  two unnamed arguments.
• fortify.SpatialPolygonsDataFrame() now calls polygons without
  requiring the sp to be loaded first (@seancarmody, #879).
• The outliers of geom_boxplot() use the default colour, size and shape from
  geom_point(). Changing the defaults of geom_point() with
  update_geom_defaults() will apply the same changes to the outliers of
  geom_boxplot(). Changing the defaults for the outliers was previously not
  possible. (@ThierryO, #757)
• geom_dotplot() now works with qplot(). (@rasmusab. Fixes #825)
• Marginal improvements to theme_bw() and theme_classic() (@jiho, #934)
• stat_smooth() checks for method = "auto" and method = "glm" in
  a safer way.
• Add "none" to documentation of theme() for parameter legend.position
  (@krlmlr, #829).

Removed functionality

• ggpcp(), ggfluctuation(), ggmissing(), ggstructure(), and
  ggorder() are now defunct and have been removed.