set_alpha

Color values in R are often represented as strings of hexadecimal
colors or named colors. This package offers fast conversion of
these color representations to either an array of red/green/blue/alpha values
or to the packed integer format used in native raster objects. Functions
for conversion are also exported at the 'C' level for use in other packages.
This fast conversion
of colors is implemented using an order-preserving minimal perfect hash
derived from Majewski et al (1996) "A Family of Perfect Hashing Methods"
<doi:10.1093/comjnl/39.6.547>.

Mike Cheng

colorfast

Fast Conversion of R Colors to Color Component Values and Native
Packed Integer Format

set_alpha function

<dl><dt>icol</dt>
<dd>Integer vector (where the 4 bytes making up each integer represent 
the RGBA values of the color)</dd>
<dt>alpha</dt>
<dd>numeric alpha value in range [0, 1]. Length of 1, or same length as 'col'</dd></dl>

Arguments

Set alpha value of integer colors — set_alpha

<dl>

<dt>icol</dt>
<dd>Integer vector (where the 4 bytes making up each integer represent 
the RGBA values of the color)</dd>


<dt>alpha</dt>
<dd>numeric alpha value in range [0, 1]. Length of 1, or same length as 'col'</dd>

</dl>

set_alpha: Set alpha value of integer colors

Description

Usage

Value

Arguments

Examples