The rgbArray function constructs an integer array whose values are
byte-packed representations of 8-bit RGBA colour values. The channels
attribute (with value 3 or 4) indicates how many channels are being used.
The resulting array can be used to construct an RGB(A) NIfTI image, or
converted to standard R colour strings using the as.character method.
The indexing method returns another object of the same type.
rgbArray(red, green, blue, alpha, max = NULL, dim = NULL, ...)# S3 method for rgbArray
[(x, i, j, ..., drop = TRUE)
# S3 method for rgbArray
as.raster(x, ...)
# S3 method for rgbArray
as.character(x, flatten = TRUE, ...)
rgbArray and the indexing ([) method return an
integer-mode array of class "rgbArray". The as.raster
method returns a raster object, valid for 2D arrays only. The
as.character method returns a character-mode vector of colour
strings with or without dimensions.
A numeric vector (or array) of red channel values. If this is the only channel argument, it can also be a character vector of colour values (including alpha, if required), or a numeric array whose last dimension is 2 (for grey + alpha), 3 (for RGB) or 4 (for RGBA).
Numeric vectors (or arrays) containing values for
the appropriate channel. These will be combined with the red values
using cbind, and hence recycled as necessary. Alpha, or green and
blue, can be missing.
The maximum possible value for any channel. The default is 255 when the data is of integer mode, and 1 otherwise. Values above this, or below zero, will be clipped to the appropriate extreme.
An integer vector of dimensions for the final array. The
dimensions of red are used if this is NULL.
For rgbArray, additional attributes to set on the result,
such as pixdim. These are passed directly to
structure. For the indexing method, additional indices.
An rgbArray object.
Index vectors, which are passed to the array method.
Whether or not to drop unitary dimensions. rgbArray
objects currently always have a dim attribute, so if the result is
a vector it will have a remaining single-element dimension equal to its
length.
Logical value. If FALSE, the dimensions of x
will be retained in the result. The default is TRUE, for
consistency with the usual behaviour of as.character, which strips
all attributes.
Jon Clayden <code@clayden.org>