mjc-colours: colours, hex-colours and rgb-colours

In drmjc/mjcgraphics: mjc's graphics library

Description

A collection of functions to convert colours from names (aka colours), hex values (aka hex) and RGB 3 character numeric's (aka rgb). This is old code, and is crying out for at least some S3-class love. It was written to facilitate the interpolation of lots of colours, which requires named colours to be numerically represented. This code allows colour.step to do its thing, though newer code in the RColorBrewer package may make much of this redundant.

Usage

  colours.hex()

  colours.rgb()

  is.colour(col)

  is.hex.colour(hex)

  is.rgb.colour(rgb)

  colour2rgb(col = NULL)

  colour2hex(col = NULL)

  hex2rgb(hex = NULL)

  rgb2hex(rgb)

  hex2colour(hex, cols.rgb = colours.rgb())

  rgb2colour(rgb, cols.rgb = colours.rgb())

  inverse.colour(col)

Arguments

col	a vector of values in the colour format: eg “white”
rgb	a vector of colours in the rgb format; ie a 3-column matrix of [0,255] values, one colour per row.
hex	a vector of colours in the hex format: eg “#FF00FF”
cols.rgb	the pool of colours with which to map hex to in rgb format. Leave as default to get the normal "R colours". NB: If cols.rgb doesn't have names, then the index into cols will be returned. If cols.rgb has valid names, then they will be returned.

Details

grDevices provides colours, and col2rgb. We wanted a hexadecimal representation of colours which included an alpha channel, as well as methods for checking colours, converting between colour types, and generating a spectrum of colours.

Value

colours, colours.hex, colours.rgb: a vector of col-format colours, hex-format colours, or matrix of rgb-format colours, 1 row per colour.

is.colour, is.hex.colour, is.rgb.colour: logical.

colour2rgb, colour2hex, hex2rgb, rgb2hex, hex2colour, rgb2colour: a vector of colour formats, converted from one to another.

hex2colour: a vector of the name of R colours; eg c("white", "magenta", "lightblue") or a vector of indices into the cols.rgb vector, if no valid names were found in the cols.rgb object. rgb2colour: a vector of the name of R colours; eg c("white", "magenta", "lightblue"), or a vector of indices into the cols.rgb vector, if no valid names were found in the cols.rgb object.

inverse.colour: a vector of colours

Allowed colour Formats

We've named the default colours provided by grDevices the col format, for want of a better name.

• col:"White", "white", "Black", "green"

• hex:"#FF00FF", "#FF00FFAE"

• rgb:matrix(c(0,255,0), 1, 3)

colour types

colours, colours.hex, colours.rgb: return the hex, or rgb representations of the named colours provided by colours from grDevices.

colour checks

is.colour, is.hex.colour, is.rgb.colour: methods for checking whether the input is one of the 3 colour types, the hex colour type, or rgb colour type, respectively.

colour conversion

colour2rgb, colour2hex: convert from col format
hex2rgb, hex2colour: convert from hex format
rgb2hex, rgb2colour: convert from rgb format
Note, hex2colour: there are 256^3 possible hex's but only length(colours()) possible outputs, so the closest colour for each hex is determined. This function is the opposite of grDevices:col2rgb, and also is the opposite of colour2rgb
Note, rgb2colour: there are 256^3 possible x's but only length(cols.rgb()) possible outputs, so the closest colour for each x is determined. This function is the opposite of grDevices:col2rgb, and also is the opposite of colour2rgb

inverse.colour

inverse a col-format colour & return the hex-format colour

Author(s)

Mark Cowley, 29/3/07

Examples

colours()[1:5]
# [1] "white"         "aliceblue"     "antiquewhite"  "antiquewhite1"
# [5] "antiquewhite2"
colours.hex()[1:5]
#     white     aliceblue  antiquewhite antiquewhite1 antiquewhite2
# "#FFFFFF"     "#F0F8FF"     "#FAEBD7"     "#FFEFDB"     "#EEDFCC"
colours.rgb()[1:5,]
#               red green blue
# white         255   255  255
# aliceblue     240   248  255
# antiquewhite  250   235  215
# antiquewhite1 255   239  219
# antiquewhite2 238   223  204

is.colour("white") # TRUE
is.colour("#FFFFFF") # FALSE
is.colour(c(255,255,255)) # FALSE

is.hex.colour("white") # FALSE
is.hex.colour("#FFFFFF") # TRUE
is.hex.colour(c(255,255,255)) # FALSE

is.rgb.colour("white") # FALSE
is.rgb.colour("#FFFFFF") # FALSE
is.rgb.colour(c(255,255,255)) # TRUE

colour2rgb("White")
#       red green blue
# White 255   255  255
colour2hex("White")
#     White
# "#FFFFFF"
hex2rgb( "#FF00E0" )
#      red green blue
# [1,] 255     0  224
rgb2hex( matrix(c(255,128,255),1,3) )
# [1] #FF80FF
hex2colour( "#FF80FF" )
# [1] "orchid1"
rgb2colour(matrix(c(255,128,255), 1, 3))
# [1] "orchid1"

inverse.colour("red")
#       red
# "#00FFFF"
inverse.colour("orchid1")
#   orchid1
# "#007C05"

drmjc/mjcgraphics documentation built on May 15, 2019, 2:40 p.m.