Create a matrix from vector to represent colors in gradient

Source: R/style.R

Create a matrix from vector to represent colors in gradient

gradient(x, min.color, max.color, alpha = NULL, use.names = TRUE, na.rm = TRUE)

Arguments

x

a numeric vector.

min.color

color of minimum value.

max.color

color of maximum value.

alpha

logical of whether to include alpha channel. NULL to let the function decide by input.

use.names

logical of whether to preserve names of input vector.

na.rm

logical indicating whether to ignore missing values as x is normalized. (defult is TRUE)

Value

a matrix with rgba columns in which each row corresponds to the rgba value (0-255) of each element in input vector x. Use csscolor

to convert the matrix to css color strings compatible with web browsers.

See also

csscolor()

Examples

gradient(c(1,2,3,4,5), "white", "red")
#>       [,1] [,2] [,3] [,4] [,5]
#> red    255  255  255  255  255
#> green  255  191  127   63    0
#> blue   255  191  127   63    0
gradient(c(5,4,3,2,1), "white", "red")
#>       [,1] [,2] [,3] [,4] [,5]
#> red    255  255  255  255  255
#> green    0   63  127  191  255
#> blue     0   63  127  191  255
gradient(c(1,3,2,4,5), "white", "red")
#>       [,1] [,2] [,3] [,4] [,5]
#> red    255  255  255  255  255
#> green  255  127  191   63    0
#> blue   255  127  191   63    0
gradient(c(1,3,2,4,5), rgb(0,0,0,0.5), rgb(0,0,0,1), alpha = TRUE)
#>       [,1] [,2] [,3] [,4] [,5]
#> red      0    0    0    0    0
#> green    0    0    0    0    0
#> blue     0    0    0    0    0
#> alpha  128  191  159  223  255