Graphical scales map data to aesthetics, and provide methods for automatically determining breaks and labels for axes and legends.
One of the most difficult parts of any graphics package is scaling, converting from data values to perceptual properties. The inverse of scaling, making guides (legends and axes) that can be used to read the graph, is often even harder! The idea of the scales
package is to implement scales in a way that is graphics system agnostic, so that everyone can benefit by pooling knowledge and resources about this tricky topic.
The scales
package is made up of the following interdependent components
Palettes, pal for short, describe the useful palettes of aesthetics.
Transformations, trans for short, describe common scale transformations, their inverses, and ways of generating breaks and labels.
Bounds: various ways of rescaling the data
Scaling functions: pull together palettes, bounding functions and transformations to provide a complete pathway from raw data to perceptual properties
Mutable ranges: in many graphics pathways, scale ranges can not be computed in a single pass, but must be computed over multiple groups or multiple panels. The mutable ranges (implemented with R's new reference based class) provide a thin layer of mutability to make this task easier.
Guide-related:
New function regular_minor_breaks()
calculates minor breaks as a property
of the transformation (@karawoo).
Adds viridis_pal()
for creating palettes with color maps from the
viridisLite package (@karawoo).
Switched from reference classes to R6 (#96).
rescale()
and rescale_mid()
are now S3 generics, and work with numeric
,
Date
, POSIXct
, POSIXlt
and bit64::integer64
objects (@zeehio, #74).
extended_breaks()
no longer fails on pathological inputs
New hms_trans()
for transforming hms time vectors.
train_discrete()
gets a new na.rm
argument which controls whether
NA
s are preserved or dropped.
Switched from NEWS
to NEWS.md
manual_pal()
produces a warning if n is greater than the number of values
in the palette (@jrnold, #68).
precision(0)
now returns 1, which means percent(0)
now returns 0% (#50).
scale_continuous()
uses a more correct check for numeric values.
NaN is correctly recognised as a missing value by the gradient palettes (ggplot2#1482).
rescale()
preserves missing values in input when the range of x
is
(effectively) 0 (ggplot2#985).
Continuous colour palettes now use colour_ramp()
instead of colorRamp()
.
This only supports interpolation in Lab colour space, but is hundreds of
times faster.
date_format()
gains an option to specify time zone (#51).
dollar_format()
is now more flexible and can add either prefixes or suffixes
for different currencies (#53). It gains a negative_parens
argument
to show negative values as ($100)
and now passes missing values through
unchanged (#40, @dougmitarotonda).
New ordinal_format()
generates ordinal numbers (1st, 2nd etc)
(@aaronwolen, #55)
New unit_format()
makes it easier to add units to labels, optionally
scaling (@ThierryO, 46)
New wrap_format()
function to wrap character vectors to a desired width.
(@jimhester, #37).
New color scaling functions col_numeric()
, col_bin()
, col_quantile()
,
and col_factor()
. These functions provide concise ways to map continuous or
categorical values to color spectra.
New colour_ramp()
function for performing color interpolation in the CIELAB
color space (like grDevices::colorRamp(space = 'Lab')
, but much faster).
boxcox_trans()
returns correct value when p is close to zero (#31).
dollar()
and percent()
both correctly return a zero length string
for zero length input (@BrianDiggs, #35)
brewer_pal()
gains a direction
argument to easily invert the order
of colours (@jiho, #36).
show_col()
has additional options to showcase colors better (@jiho, #52)
Relaxed tolerance in zero_range()
to .Machine$double.eps * 1000
(#33).
Eliminate stringr dependency.
Fix outstanding errors in R CMD check
floor_time
calls to_time
, but that function was moved into a function
so it was no longer available in the scales namespace. Now floor_time
has its own copy of that function. (Thanks to Stefan Novak)
Color palettes generated by brewer_pal
no longer give warnings when fewer
than 3 colors are requested. (Winston Chang)
abs_area and
rescale_maxfunctions have been added, for scaling the area of points to be proportional to their value. These are used by
scale_size_area` in ggplot2.
zero_range
has improved behaviour thanks to Brian Diggs.
brewer_pal
complains if you give it an incorrect palette type. (Fixes #15,
thanks to Jean-Olivier Irisson)
shape_pal
warns if asked for more than 6 values. (Fixes #16, thanks to
Jean-Olivier Irisson)
time_trans
gains an optional argument tz
to specify the time zone to use
for the times. If not specified, it will be guess from the first input with
a non-null time zone.
date_trans
and time_trans
now check that their inputs are of the correct
type. This prevents ggplot2 scales from silently giving incorrect outputs
when given incorrect inputs.
Change the default breaks algorithm for cbreaks()
and trans_new()
.
Previously it was pretty_breaks()
, and now it's extended_breaks()
,
which uses the extended()
algorithm from the labeling package.
fixed namespace problem with fullseq
suppressWarnings
from train_continuous
so zero-row or all infinite data
frames don't potentially cause problems.
check for zero-length colour in gradient_n_pal
added extended_breaks
which implements an extension to Wilkinson's
labelling approach, as implemented in the labeling
package. This should
generally produce nicer breaks than pretty_breaks
.
alpha
can now preserve existing alpha values if alpha
is missing.
log_breaks
always gives breaks evenly spaced on the log scale, never
evenly spaced on the data scale. This will result in really bad breaks for
some ranges (e.g 0.5-0.6), but you probably shouldn't be using log scales in
that situation anyway.
censor
and squish
gain only.finite
argument and default to operating
only on finite values. This is needed for ggplot2, and reflects the use of
Inf and -Inf as special values.
bounds
functions now force
evaluation of range to avoid bug with S3
method dispatch inside primitive functions (e.g. [
)
Simplified algorithm for discrete_range
that is robust to
stringsAsFactors
global option. Now, the order of a factor will only be
preserved if the full factor is the first object seen, and all subsequent
inputs are subsets of the levels of the original factor.
scientific
ensures output is always in scientific format and off the
specified number of significant digits. comma
ensures output is never in
scientific format. (Fixes #7)
Another tweak to zero_range
to better detect when a range has zero length.
(Fixes #6)