col_numeric
Color mapping
Conveniently maps data values (numeric or factor/character) to colors according to a given palette, which can be provided in a variety of formats.
Usage
col_numeric(palette, domain, na.color = "#808080")
col_bin(palette, domain, bins = 7, pretty = TRUE, na.color = "#808080")
col_quantile(palette, domain, n = 4, probs = seq(0, 1, length.out = n + 1), na.color = "#808080")
col_factor(palette, domain, levels = NULL, ordered = FALSE, na.color = "#808080")
Arguments
 palette
 The colors or color function that values will be mapped to
 domain
 The possible values that can be mapped.
For
col_numeric
andcol_bin
, this can be a simple numeric range (e.g.c(0, 100)
);col_quantile
needs representative numeric data; andcol_factor
needs categorical data.If
NULL
, then whenever the resulting color function is called, thex
value will represent the domain. This implies that if the function is invoked multiple times, the encoding between values and colors may not be consistent; if consistency is needed, you must provide a nonNULL
domain.  na.color
 The color to return for
NA
values. Note thatna.color=NA
is valid.  bins
 Either a numeric vector of two or more unique cut points or a single number (greater than or equal to 2) giving the number of intervals into which the domain values are to be cut.
 pretty
 Whether to use the function
pretty()
to generate the bins when the argumentbins
is a single number. Whenpretty = TRUE
, the actual number of bins may not be the number of bins you specified. Whenpretty = FALSE
,seq()
is used to generate the bins and the breaks may not be "pretty".  n
 Number of equalsize quantiles desired. For more precise control,
use the
probs
argument instead.  probs
 See
quantile
. If provided, then
argument is ignored.  levels
 An alternate way of specifying levels; if specified, domain is ignored
 ordered
 If
TRUE
anddomain
needs to be coerced to a factor, treat it as already in the correct order
Details
col_numeric
is a simple linear mapping from continuous numeric data
to an interpolated palette.
col_bin
also maps continuous numeric data, but performs
binning based on value (see the cut
function).
col_quantile
similarly bins numeric data, but via the
quantile
function.
col_factor
maps factors to colors. If the palette is
discrete and has a different number of colors than the number of factors,
interpolation is used.
The palette
argument can be any of the following:
 A character vector of RGB or named colors. Examples:
palette()
,c("#000000", "#0000FF", "#FFFFFF")
,topo.colors(10)
 The name of an RColorBrewer palette, e.g.
"BuPu"
or"Greens"
.  A function that receives a single value between 0 and 1 and returns a color. Examples:
colorRamp(c("#000000", "#FFFFFF"), interpolate="spline")
.
Value

A function that takes a single parameter
x
; when called with a
vector of numbers (except for col_factor
, which expects
factors/characters), #RRGGBB color strings are returned.
Examples
pal < col_bin("Greens", domain = 0:100)
show_col(pal(sort(runif(10, 60, 100))))
# Exponential distribution, mapped continuously
show_col(col_numeric("Blues", domain = NULL)(sort(rexp(16))))
# Exponential distribution, mapped by interval
show_col(col_bin("Blues", domain = NULL, bins = 4)(sort(rexp(16))))
# Exponential distribution, mapped by quantile
show_col(col_quantile("Blues", domain = NULL)(sort(rexp(16))))
# Categorical data; by default, the values being colored span the gamut...
show_col(col_factor("RdYlBu", domain = NULL)(LETTERS[1:5]))
# ...unless the data is a factor, without droplevels...
show_col(col_factor("RdYlBu", domain = NULL)(factor(LETTERS[1:5], levels=LETTERS)))
# ...or the domain is stated explicitly.
show_col(col_factor("RdYlBu", levels = LETTERS)(LETTERS[1:5]))