Compute a color ramp scaled from white to a target color

Compute a color ramp scaled from white to a target color

Usage

get_color_scale(n, col = "red", frac_min = 0.35)

Arguments

n

numeric vector with non-negative values.

col

character string, target color name or hexadecimal code (default "red").

frac_min

numeric between 0 and 1, minimum intensity threshold for the lowest positive value (default 0.35).

Value

A character vector of hexadecimal colors and/or "transparent", of length equal to n, or NULL if negative values exist.

Details

Interpolates RGB values between "white" and col. Strictly positive values scale from frac_min (smallest positive value) to 1 (maximum value). Values equal to 0 or NA return "transparent". If negative values are present, a warning is issued and NULL is returned.

Examples

get_color_scale(c(0, 1, 5, 12, NA))        # with integer
#> [1] "transparent" "#FFA5A5"     "#FF6969"     "#FF0000"     "transparent"
get_color_scale(c(0, 1.2, 5, 12, NA))      # with numeric
#> [1] "transparent" "#FFA5A5"     "#FF6B6B"     "#FF0000"     "transparent"
get_color_scale(c(0, NA))                  # all transparent
#> [1] "transparent" "transparent"
get_color_scale(c())                       # empty character
#> character(0)
get_color_scale(c(2, 2, 2), col = "blue")  # all maximum blue
#> [1] "#0000FF" "#0000FF" "#0000FF"
get_color_scale(c(-1, 2))                  # NULL with warning
#> Warning: No negative value is allowed. NULL returned.
#> NULL