Color palettes

Functions to create color palettes.

The functions are:

rainbowPalette	Contiguous rainbow color palette,
heatPalette	Contiguous heat color palette,
terrainPalette	Contiguous terrain color palette,
topoPalette	Contiguous topo color palette,
cmPalette	Contiguous cm color palette,
greyPalette	R's gamma-corrected gray palette,
timPalette	Tim's Matlab like color palette,
rampPalette	Color ramp palettes,
seqPalette	Sequential color brewer palettes,
divPalette	Diverging color brewer palettes,
qualiPalette	Qualified color brewer palettes,
focusPalette	Red, green blue focus palettes,
monoPalette	Red, green blue mono palettes.

Usage

rainbowPalette(n = 64, ...) 
heatPalette(n = 64, ...) 
terrainPalette(n = 64, ...) 
topoPalette(n = 64, ...) 
cmPalette(n = 64, ...) 

greyPalette(n = 64, ...)
timPalette(n = 64)

rampPalette(n, name = c("blue2red", "green2red", "blue2green",     
    "purple2green", "blue2yellow", "cyan2magenta"))
    
seqPalette(n, name = c(
    "Blues", "BuGn", "BuPu", "GnBu", "Greens", "Greys", "Oranges", 
    "OrRd", "PuBu", "PuBuGn", "PuRd", "Purples", "RdPu", "Reds", 
    "YlGn", "YlGnBu", "YlOrBr", "YlOrRd"))
divPalette(n, name = c(
    "BrBG", "PiYG", "PRGn", "PuOr", "RdBu", "RdGy", "RdYlBu", "RdYlGn", 
    "Spectral"))   
qualiPalette(n, name = c(
    "Accent", "Dark2", "Paired", "Pastel1", "Pastel2", "Set1", "Set2", 
    "Set3")) 
    
focusPalette(n, name = c("redfocus", "greenfocus", "bluefocus"))
monoPalette(n, name = c("redmono", "greenmono", "bluemono"))

Arguments

n

an integer, giving the number of greys or colors to be constructed.

name

a character string, the name of the color set.

...

arguments to be passed, see the details section

Details

All Rmetrics' color sets are named as fooPalette, where the prefix foo denotes the name of the underlying color set.

R's Contiguous Color Palettes:

Palettes for n contiguous colors are implemented in the grDevices package. To conform with Rmetrics' naming convention for color palettes we have build wrappers around the underlying functions. These are the rainbowPalette, heatPalette, terrainPalette, topoPalette, and the cmPalette.

Conceptually, all of these functions actually use (parts of) a line cut out of the 3-dimensional color space, parametrized by the function hsv(h,s,v,gamma), where gamma=1 for the fooPalette function, and hence, equispaced hues in RGB space tend to cluster at the red, green and blue primaries.

Some applications, such as contouring, require a palette of colors which do not wrap around to give a final color close to the starting one. To pass additional arguments to the underlying functions see help(rainbow). With rainbow, the parameters start and end can be used to specify particular subranges of hues. Synonym function calls are rainbow, heat.colors, terrain.colors, topo.colors, and cm.colors.

R's Gamma-Corrected Gray Palette:

grayPalette chooses a series of n gamma-corrected gray levels. The range of the gray levels can be optionally monitored through the ... arguments, for details see help(gray.colors), which is a synonym function call in the grDevices package.

Tim's Matlab like Color Palette:

timPalette creates a color set ranging from blue to red, and passes through the colors cyan, yellow, and orange. It comes from the Matlab software, originally used in fluid dynamics simulations. The function here is a copy from R's contributed package fields doing a spline interpolation on n=64 color points.

Color Ramp Palettes:

rampPalette creates several color ramps. The function is implemented from Tim Keitt's contributed R package colorRamps. Supported through the argument name are the following color ramps: "blue2red", "green2red", "blue2green", "purple2green", "blue2yellow", "cyan2magenta".

Color Brewer Palettes:

The functions seqPalette, divPalette, and qualiPalette create color sets according to R's contributed RColorBrewer package. The first letter in the function name denotes the type of the color set: "s" for sequential palettes, "d" for diverging palettes, and "q" for qualitative palettes.

Sequential palettes are suited to ordered data that progress from low to high. Lightness steps dominate the look of these schemes, with light colors for low data values to dark colors for high data values. The sequential palettes names are: Blues, BuGn, BuPu, GnBu, Greens, Greys, Oranges, OrRd, PuBu, PuBuGn, PuRd, Purples, RdPu, Reds, YlGn, YlGnBu, YlOrBr, YlOrRd.

Diverging palettes put equal emphasis on mid-range critical values and extremes at both ends of the data range. The critical class or break in the middle of the legend is emphasized with light colors and low and high extremes are emphasized with dark colors that have contrasting hues. The diverging palettes names are: BrBG, PiYG, PRGn, PuOr, RdBu, RdGy, RdYlBu, RdYlGn, Spectral.

Qualitative palettes do not imply magnitude differences between legend classes, and hues are used to create the primary visual differences between classes. Qualitative schemes are best suited to representing nominal or categorical data. The qualitative palettes names are: Accent, Dark2, Paired, Pastel1, Pastel2, Set1, Set2, Set3.

In contrast to the original color brewer palettes, the palettes here are created by spline interpolation from the color variation with the most different values, i.e for the sequential palettes these are 9 values, for the diverging palettes these are 11 values, and for the qualitative palettes these are between 8 and 12 values dependeing on the color set.

Graph Color Palettes

The function perfanPalette creates color sets inspired by R's contributed package Performance Analytics. These color palettes have been designed to create readable, comparable line and bar graphs with specific objectives.

Focused Color Palettes

Color sets designed to provide focus to the data graphed as the first element. This palette is best used when there is clearly an important data set for the viewer to focus on, with the remaining data being secondary, tertiary, etc. Later elements graphed in diminishing values of gray.

Monochrome Color Palettes

These include color sets for monochrome color displays.

Value

a character string of color strings

Note

The palettes are wrapper functions provided in several contributed R packages. These include:

Cynthia Brewer and Mark Harrower for the brewer palettes,
Peter Carl and Brian G. Peterson for the "PerformanceAnalytics" package,
Tim Keitt for the "colorRamps" package,
Ross Ihaka for the "colorspace" package,
Tomas Aragon for the "epitools" package,
Doug Nychka for the "fields" package,
Erich Neuwirth for the "RColorBrewer" package.

Additional undocumented hidden functions:

.asRGB	Converts any R color to RGB (red/green/blue),
.chcode	Changes from one to another number system,
.hex.to.dec	Converts heximal numbers do decimal numbers,
.dec.to.hex	Converts decimal numbers do heximal numbers.

Examples

greyPalette()
#>  [1] "#4D4D4D" "#525252" "#575757" "#5C5C5C" "#606060" "#646464" "#686868"
#>  [8] "#6C6C6C" "#707070" "#737373" "#777777" "#7A7A7A" "#7D7D7D" "#808080"
#> [15] "#838383" "#868686" "#898989" "#8C8C8C" "#8E8E8E" "#919191" "#949494"
#> [22] "#969696" "#999999" "#9B9B9B" "#9D9D9D" "#A0A0A0" "#A2A2A2" "#A4A4A4"
#> [29] "#A7A7A7" "#A9A9A9" "#ABABAB" "#ADADAD" "#AFAFAF" "#B1B1B1" "#B3B3B3"
#> [36] "#B5B5B5" "#B7B7B7" "#B9B9B9" "#BBBBBB" "#BDBDBD" "#BFBFBF" "#C1C1C1"
#> [43] "#C3C3C3" "#C5C5C5" "#C6C6C6" "#C8C8C8" "#CACACA" "#CCCCCC" "#CDCDCD"
#> [50] "#CFCFCF" "#D1D1D1" "#D2D2D2" "#D4D4D4" "#D6D6D6" "#D7D7D7" "#D9D9D9"
#> [57] "#DBDBDB" "#DCDCDC" "#DEDEDE" "#DFDFDF" "#E1E1E1" "#E2E2E2" "#E4E4E4"
#> [64] "#E6E6E6"