R: Get Color on a Defined Color Range

FindColor {DescTools} | R Documentation

## Get Color on a Defined Color Range

### Description

Find a color on a defined color range depending on the value of x. This is helpful for colorcoding numeric values.

### Usage

    FindColor(x, cols = rev(heat.colors(100)),
              min.x = NULL, max.x = NULL, all.inside = FALSE)

### Arguments

`x` | numeric.
`cols` | a vector of colors.
`min.x` | the x-value to be used for the left edge of the first color. If left to the default `NULL` `min(pretty(x))` will be used.
`max.x` | the x-value to be used for the right edge of the last color. If left to the default `NULL` `max(pretty(x))` will be used.
`all.inside` | logical; if true, the returned indices are coerced into `1, ..., N-1`, i.e., `0` is mapped to `1` and `N` to `N-1`.

### Details

For the selection of colors the option `rightmost.closed` in the used function `findInterval` is set to TRUE. This will ensure that all values on the right edge of the range are assigned a color. How values outside the boundaries of min.x and max.x should be handled can be controlled by `all.inside`. Set this value to TRUE, if those values should get the colors at the edges or set it to FALSE, if they should remain white (which is the default).

Note that `findInterval` closes the intervals on the left side, e.g. [0, 1). This option can't be changed. Consequently will x-values lying on the edge of two colors get the color of the bigger one.

### Author(s)

Andri Signorell <andri@signorell.net>

### See Also

`findInterval`

### Examples

    Canvas(7, main="Use of function FindColor()")

    # get some data
    x <- c(23, 56, 96)
    # get a color range from blue via white to red
    cols <- colorRampPalette(c("blue","white","red"))(100)
    ColorLegend(x="bottomleft", cols=cols, labels=seq(0, 100, 10), cex=0.8)

    # and now the color coding of x:
    (xcols <- FindColor(x, cols, min.x=0, max.x=100))

    # this should be the same as
    cols[x+1]

    # how does it look like?
    y0 <- c(-5, -2, 1)
    text(x=1, y=max(y0)+2, labels="Color coding of x:")
    text(x=1.5, y=y0, labels=x)
    DrawRegPolygon(x=3, y=y0, nv=4, rot=pi/4, col=xcols)
    text(x=6, y=y0, labels=xcols)

    # how does the function select colors?
    Canvas(xlim = c(0,1), ylim = c(0,1))
    cols <- c(red="red", yellow="yellow", green="green", blue="blue")
    ColorLegend(x=0, y=1, width=1, cols=rev(cols), horiz = TRUE,
                labels=Format(seq(0, 1, .25), digits=2), frame="grey", cex=0.8 )
    x <- c(-0.2, 0, 0.15, 0.55, .75, 1, 1.3)
    arrows(x0 = x, y0 = 0.6, y1 = 0.8, angle = 15, length = .2)
    text(x=x, y = 0.5, labels = x, adj = c(0.5,0.5))
    text(x=x, y = 0.4, labels = names(FindColor(x, cols=cols,
       min.x = 0, max.x = 1, all.inside = TRUE)), adj = c(0.5,0.5))
    text(x=x, y = 0.3, labels = names(FindColor(x, cols=cols,
       min.x = 0, max.x = 1, all.inside = FALSE)), adj = c(0.5,0.5))

[Package DescTools version 0.99.28 Index]