make R colors darker (or lighter)

Makes R colors darker or lighter based upon darkFactor

Usage

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.

Value

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.

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()

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));