makeColorDarker function

make R colors darker (or lighter)

Makes R colors darker or lighter based upon darkFactor

makeColorDarker(
  hexColor,
  darkFactor = 2,
  sFactor = 1,
  fixAlpha = NULL,
  verbose = FALSE,
  keepNA = FALSE,
  useMethod = 1,
  ...
)

Arguments

• hexColor: character vector of colors to adjust
• darkFactor: numeric value to adjust darkness, values above 1 make the color darker, values below 1 (or below 0) make the color brighter.
• sFactor: numeric value to adjust saturation, values above 1 become more saturated.
• fixAlpha: numeric, default NULL, to assign a fixed alpha transparency value, where 0 is transparent and 1 is opaque.
• verbose: logical indicating whether to print verbose output.
• keepNA: logical, default FALSE, whether to keep NA values as NA values in the output, otherwise NA values are considered grey input.
• useMethod: integer with two alternate methods, 1 is default.
• ...: Additional arguments are ignored.

Returns

character vector of R colors.

Details

This function was originally intended to create border colors, or to create slightly darker colors used for labels. It is also useful for for making colors lighter, in adjusting color saturation up or down, or applying alpha transparency during the same step.

Note when colors are brightened beyond value=1, the saturation is gradually reduced in order to produce a visibly lighter color. The saturation minimu is set to 0.2, to maintain at least some amount of color.

Examples

colorV <- c("red","orange","purple","blue");
colorVdark2 <- makeColorDarker(colorV, darkFactor=2);
colorVlite2 <- makeColorDarker(colorV, darkFactor=-2);
showColors(cexCellnote=0.7,
   list(
   `darkFactor=2`=colorVdark2,
   `original colors`=colorV,
   `darkFactor=-2`=colorVlite2
   ));

# these adjustments work really well inside a network diagram
# when coloring nodes, and providing an outline of comparable
# color.
plot(x=c(1,2,1,2), y=c(1,2,2,1), pch=21,
   xaxt="n", yaxt="n", xlab="", ylab="",
   xlim=c(0.5,2.5), ylim=c(0.5,2.5),
   bg=colorV, col=colorVdark2, cex=4, lwd=2);
graphics::points(x=c(1,2,1,2), y=c(1,2,2,1), pch=20, cex=4,
   col=colorVlite2);

# Making a color lighter can make it easier to add labels
# The setTextContrastColor() function also helps.
graphics::text(x=c(1,2,1,2), y=c(1,2,2,1), 1:4,
   col=setTextContrastColor(colorVlite2));

See Also

Other jam color functions: alpha2col(), applyCLrange(), col2alpha(), col2hcl(), col2hsl(), col2hsv(), color2gradient(), fixYellow(), fixYellowHue(), getColorRamp(), hcl2col(), hsl2col(), hsv2col(), isColor(), kable_coloring(), rainbow2(), rgb2col(), setCLranges(), setTextContrastColor(), showColors(), unalpha(), warpRamp()