Continuous color palettes.

Functions generating color palettes usable with R graphical functions. These palettes are continuous, contrast being accentuated by darkening and lightening extreme values. prevR.demo.pal plot the available palettes. prevR.colors.qgis.pal export a palette in a text file readable by Quantum GIS, an open-source mapping software.

Usage

prevR.colors.blue(n = 10)

prevR.colors.blue.inverse(n = 10)

prevR.colors.gray(n = 10)

prevR.colors.gray.inverse(n = 10)

prevR.colors.green(n = 10)

prevR.colors.green.inverse(n = 10)

prevR.colors.red(n = 10)

prevR.colors.red.inverse(n = 10)

prevR.demo.pal(n, border = if (n < 32) "light gray" else NA, main = NULL)

prevR.colors.qgis.pal(file, at, pal = "red", inverse = FALSE)

Arguments

n

number of different colors in the palette.

border

border color.

main

title.

file

file name with extension.

at

list of values of the palette.

pal

color palette to use ("red", "green", "blue" or "gray").

inverse

use the inverse palette?

Value

prevR.demo.pal() plot the color palettes.

prevR.colors.qgis.pal() export a color palette in a text file readable by Quantum GIS.

The other functions return a list of colors coded in hexadecimal.

Details

prevR.colors.red() produces a color gradation from white/yellow to red/dark red.

prevR.colors.blue() produces a color gradation from light blue to dark blue.

prevR.colors.green() produces a color gradation from light green to dark green.

prevR.colors.gray() produces a color gradation from white/light gray to dark gray/black.

Functions with a suffix .inverse produce the same color gradation, but from dark colors to light ones.

Note

To obtain the list of colors in RGB (Red/Green/Blue), use the function grDevices::col2rgb(). The code of prevR.demo.pal() was adapted from the function demo.pal presented in the examples of grDevices::rainbow().

See also

Other color palettes are available in R. See for example grDevices::rainbow() or the package RColorBrewer.

Examples

prevR.demo.pal(25)

prevR.colors.red(5)
#> [1] "#FFFF80" "#FFFF00" "#FF8000" "#FF0000" "#800000"
col2rgb(prevR.colors.red(5))
#>       [,1] [,2] [,3] [,4] [,5]
#> red    255  255  255  255  128
#> green  255  255  128    0    0
#> blue   128    0    0    0    0

if (FALSE) { # \dontrun{
prevR.colors.qgis.pal("palette.txt", seq(0, 25, length.out = 100), "red")
} # }