% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/scale-gradient.R, R/zxx.R
\name{scale_colour_gradient}
\alias{scale_colour_gradient}
\alias{scale_fill_gradient}
\alias{scale_colour_gradient2}
\alias{scale_fill_gradient2}
\alias{scale_colour_gradientn}
\alias{scale_fill_gradientn}
\alias{scale_colour_datetime}
\alias{scale_color_datetime}
\alias{scale_colour_date}
\alias{scale_color_date}
\alias{scale_fill_datetime}
\alias{scale_fill_date}
\alias{scale_color_gradient}
\alias{scale_color_gradient2}
\alias{scale_color_gradientn}
\title{Gradient colour scales}
\usage{
scale_colour_gradient(
  ...,
  low = "#132B43",
  high = "#56B1F7",
  space = "Lab",
  na.value = "grey50",
  guide = "colourbar",
  aesthetics = "colour"
)

scale_fill_gradient(
  ...,
  low = "#132B43",
  high = "#56B1F7",
  space = "Lab",
  na.value = "grey50",
  guide = "colourbar",
  aesthetics = "fill"
)

scale_colour_gradient2(
  ...,
  low = muted("red"),
  mid = "white",
  high = muted("blue"),
  midpoint = 0,
  space = "Lab",
  na.value = "grey50",
  guide = "colourbar",
  aesthetics = "colour"
)

scale_fill_gradient2(
  ...,
  low = muted("red"),
  mid = "white",
  high = muted("blue"),
  midpoint = 0,
  space = "Lab",
  na.value = "grey50",
  guide = "colourbar",
  aesthetics = "fill"
)

scale_colour_gradientn(
  ...,
  colours,
  values = NULL,
  space = "Lab",
  na.value = "grey50",
  guide = "colourbar",
  aesthetics = "colour",
  colors
)

scale_fill_gradientn(
  ...,
  colours,
  values = NULL,
  space = "Lab",
  na.value = "grey50",
  guide = "colourbar",
  aesthetics = "fill",
  colors
)
}
\arguments{
\item{...}{
  Arguments passed on to \code{\link[=continuous_scale]{continuous_scale}}
  \describe{
    \item{\code{scale_name}}{The name of the scale that should be used for error messages
associated with this scale.}
    \item{\code{palette}}{A palette function that when called with a numeric vector with
values between 0 and 1 returns the corresponding output values
(e.g., \code{\link[scales:area_pal]{scales::area_pal()}}).}
    \item{\code{name}}{The name of the scale. Used as the axis or legend title. If
\code{waiver()}, the default, the name of the scale is taken from the first
mapping used for that aesthetic. If \code{NULL}, the legend title will be
omitted.}
    \item{\code{breaks}}{One of:
\itemize{
\item \code{NULL} for no breaks
\item \code{waiver()} for the default breaks computed by the
\link[scales:trans_new]{transformation object}
\item A numeric vector of positions
\item A function that takes the limits as input and returns breaks
as output (e.g., a function returned by \code{\link[scales:breaks_extended]{scales::extended_breaks()}}).
Also accepts rlang \link[rlang:as_function]{lambda} function notation.
}}
    \item{\code{minor_breaks}}{One of:
\itemize{
\item \code{NULL} for no minor breaks
\item \code{waiver()} for the default breaks (one minor break between
each major break)
\item A numeric vector of positions
\item A function that given the limits returns a vector of minor breaks. Also
accepts rlang \link[rlang:as_function]{lambda} function notation.
}}
    \item{\code{n.breaks}}{An integer guiding the number of major breaks. The algorithm
may choose a slightly different number to ensure nice break labels. Will
only have an effect if \code{breaks = waiver()}. Use \code{NULL} to use the default
number of breaks given by the transformation.}
    \item{\code{labels}}{One of:
\itemize{
\item \code{NULL} for no labels
\item \code{waiver()} for the default labels computed by the
transformation object
\item A character vector giving labels (must be same length as \code{breaks})
\item An expression vector (must be the same length as breaks). See ?plotmath for details.
\item A function that takes the breaks as input and returns labels
as output. Also accepts rlang \link[rlang:as_function]{lambda} function
notation.
}}
    \item{\code{limits}}{One of:
\itemize{
\item \code{NULL} to use the default scale range
\item A numeric vector of length two providing limits of the scale.
Use \code{NA} to refer to the existing minimum or maximum
\item A function that accepts the existing (automatic) limits and returns
new limits. Also accepts rlang \link[rlang:as_function]{lambda} function
notation.
Note that setting limits on positional scales will \strong{remove} data outside of the limits.
If the purpose is to zoom, use the limit argument in the coordinate system
(see \code{\link[=coord_cartesian]{coord_cartesian()}}).
}}
    \item{\code{rescaler}}{A function used to scale the input values to the
range [0, 1]. This is always \code{\link[scales:rescale]{scales::rescale()}}, except for
diverging and n colour gradients (i.e., \code{\link[=scale_colour_gradient2]{scale_colour_gradient2()}},
\code{\link[=scale_colour_gradientn]{scale_colour_gradientn()}}). The \code{rescaler} is ignored by position
scales, which always use \code{\link[scales:rescale]{scales::rescale()}}. Also accepts rlang
\link[rlang:as_function]{lambda} function notation.}
    \item{\code{oob}}{One of:
\itemize{
\item Function that handles limits outside of the scale limits
(out of bounds). Also accepts rlang \link[rlang:as_function]{lambda}
function notation.
\item The default (\code{\link[scales:oob]{scales::censor()}}) replaces out of
bounds values with \code{NA}.
\item \code{\link[scales:oob]{scales::squish()}} for squishing out of bounds values into range.
\item \code{\link[scales:oob]{scales::squish_infinite()}} for squishing infinite values into range.
}}
    \item{\code{trans}}{For continuous scales, the name of a transformation object
or the object itself. Built-in transformations include "asn", "atanh",
"boxcox", "date", "exp", "hms", "identity", "log", "log10", "log1p", "log2",
"logit", "modulus", "probability", "probit", "pseudo_log", "reciprocal",
"reverse", "sqrt" and "time".

A transformation object bundles together a transform, its inverse,
and methods for generating breaks and labels. Transformation objects
are defined in the scales package, and are called \verb{<name>_trans} (e.g.,
\code{\link[scales:boxcox_trans]{scales::boxcox_trans()}}). You can create your own
transformation with \code{\link[scales:trans_new]{scales::trans_new()}}.}
    \item{\code{expand}}{For position scales, a vector of range expansion constants used to add some
padding around the data to ensure that they are placed some distance
away from the axes. Use the convenience function \code{\link[=expansion]{expansion()}}
to generate the values for the \code{expand} argument. The defaults are to
expand the scale by 5\% on each side for continuous variables, and by
0.6 units on each side for discrete variables.}
    \item{\code{position}}{For position scales, The position of the axis.
\code{left} or \code{right} for y axes, \code{top} or \code{bottom} for x axes.}
    \item{\code{super}}{The super class to use for the constructed scale}
  }}

\item{low, high}{Colours for low and high ends of the gradient.}

\item{space}{colour space in which to calculate gradient. Must be "Lab" -
other values are deprecated.}

\item{na.value}{Colour to use for missing values}

\item{guide}{Type of legend. Use \code{"colourbar"} for continuous
colour bar, or \code{"legend"} for discrete colour legend.}

\item{aesthetics}{Character string or vector of character strings listing the
name(s) of the aesthetic(s) that this scale works with. This can be useful, for
example, to apply colour settings to the \code{colour} and \code{fill} aesthetics at the
same time, via \code{aesthetics = c("colour", "fill")}.}

\item{mid}{colour for mid point}

\item{midpoint}{The midpoint (in data value) of the diverging scale.
Defaults to 0.}

\item{colours, colors}{Vector of colours to use for n-colour gradient.}

\item{values}{if colours should not be evenly positioned along the gradient
this vector gives the position (between 0 and 1) for each colour in the
\code{colours} vector. See \code{\link[scales:rescale]{rescale()}} for a convenience function
to map an arbitrary range to between 0 and 1.}
}
\description{
\verb{scale_*_gradient} creates a two colour gradient (low-high),
\verb{scale_*_gradient2} creates a diverging colour gradient (low-mid-high),
\verb{scale_*_gradientn} creates a n-colour gradient. For binned variants of
these scales, see the \link[=scale_colour_steps]{color steps} scales.
}
\details{
Default colours are generated with \pkg{munsell} and
\code{mnsl(c("2.5PB 2/4", "2.5PB 7/10"))}. Generally, for continuous
colour scales you want to keep hue constant, but vary chroma and
luminance. The \pkg{munsell} package makes this easy to do using the
Munsell colour system.
}
\examples{
set.seed(1)
df <- data.frame(
  x = runif(100),
  y = runif(100),
  z1 = rnorm(100),
  z2 = abs(rnorm(100))
)

df_na <- data.frame(
  value = seq(1, 20),
  x = runif(20),
  y = runif(20),
  z1 = c(rep(NA, 10), rnorm(10))
)

# Default colour scale colours from light blue to dark blue
ggplot(df, aes(x, y)) +
  geom_point(aes(colour = z2))

# For diverging colour scales use gradient2
ggplot(df, aes(x, y)) +
  geom_point(aes(colour = z1)) +
  scale_colour_gradient2()

# Use your own colour scale with gradientn
ggplot(df, aes(x, y)) +
  geom_point(aes(colour = z1)) +
  scale_colour_gradientn(colours = terrain.colors(10))

# Equivalent fill scales do the same job for the fill aesthetic
ggplot(faithfuld, aes(waiting, eruptions)) +
  geom_raster(aes(fill = density)) +
  scale_fill_gradientn(colours = terrain.colors(10))

# Adjust colour choices with low and high
ggplot(df, aes(x, y)) +
  geom_point(aes(colour = z2)) +
  scale_colour_gradient(low = "white", high = "black")
# Avoid red-green colour contrasts because ~10\% of men have difficulty
# seeing them

# Use `na.value = NA` to hide missing values but keep the original axis range
ggplot(df_na, aes(x = value, y)) +
  geom_bar(aes(fill = z1), stat = "identity") +
  scale_fill_gradient(low = "yellow", high = "red", na.value = NA)

 ggplot(df_na, aes(x, y)) +
   geom_point(aes(colour = z1)) +
   scale_colour_gradient(low = "yellow", high = "red", na.value = NA)

}
\seealso{
\code{\link[scales:seq_gradient_pal]{scales::seq_gradient_pal()}} for details on underlying
palette, \code{\link[=scale_colour_steps]{scale_colour_steps()}} for binned variants of these scales.

Other colour scales: 
\code{\link{scale_alpha}()},
\code{\link{scale_colour_brewer}()},
\code{\link{scale_colour_continuous}()},
\code{\link{scale_colour_grey}()},
\code{\link{scale_colour_hue}()},
\code{\link{scale_colour_steps}()},
\code{\link{scale_colour_viridis_d}()}
}
\concept{colour scales}
