# Color interpolation

### Description

These functions are replacements for colorRamp and colorRampPalette from the package grDevices, the only difference being that they also interpolate the alpha channel (i.e. transparency).

### Usage

1 2 3 | ```
colorRampPaletteAlpha(colors, ...)
colorRampAlpha(colors, bias = 1, interpolate = c("linear", "spline"))
``` |

### Arguments

`colors` |
colors to interpolate; must be a valid argument to |

`...` |
arguments to pass to |

`bias` |
a positive number. Higher values give more widely spaced colors at the high end. |

`interpolate` |
use spline or linear interpolation |

### Details

These functions are replacements for `colorRamp`

and `colorRampPalette`

from the
package grDevices. There are two differences: (i) these functions also interpolate the
alpha channel (i.e. transparency) and (ii) there is no `space`

parameter (only `rgb`

space is allowed).
For all the other details, see descriptions of the original package.

### Value

Both functions return a function which takes an integer argument.
For details, see description of `colorRampPalette`

### Examples

1 | ```
colorRampPaletteAlpha( c( "#FF000033", "#00FF0099" ) )( 5 )
``` |