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% File src/library/grid/man/as.raster.Rd
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% File src/library/grid/man/as.raster.Rd
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% Part of the R package, https://www.R-project.org
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% Part of the R package, https://www.R-project.org
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% Copyright 2009-2014 R Core Team
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% Copyright 2009-2015 R Core Team
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% Distributed under GPL 2 or later
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% Distributed under GPL 2 or later
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\name{as.raster}
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\name{as.raster}
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\alias{is.raster}
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\alias{is.raster}
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\alias{as.raster}
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\alias{as.raster}
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\alias{as.raster.logical}
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\alias{as.raster.logical}
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\alias{as.raster.numeric}
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\alias{as.raster.numeric}
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\alias{as.raster.raw}
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\alias{as.raster.character}
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\alias{as.raster.character}
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\alias{as.raster.matrix}
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\alias{as.raster.matrix}
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\alias{as.raster.array}
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\alias{as.raster.array}
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\title{Create a Raster Object}
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\title{Create a Raster Object}
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}
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}
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\usage{
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\usage{
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is.raster(x)
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is.raster(x)
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as.raster(x, \dots)
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as.raster(x, \dots)
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\method{as.raster}{matrix}(x, max = 1, \dots)
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\method{as.raster}{array}(x, max = 1, \dots)
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\method{as.raster}{logical}(x, max = 1, \dots)
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\method{as.raster}{logical}(x, max = 1, \dots)
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\method{as.raster}{numeric}(x, max = 1, \dots)
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\method{as.raster}{numeric}(x, max = 1, \dots)
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\method{as.raster}{character}(x, max = 1, \dots)
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\method{as.raster}{character}(x, max = 1, \dots)
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\method{as.raster}{matrix}(x, max = 1, \dots)
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\method{as.raster}{array}(x, max = 1, \dots)
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\method{as.raster}{raw}(x, max = 255L, \dots)
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}
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}
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\arguments{
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\arguments{
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  \item{x}{
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    Any R object.
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  \item{x}{any \R object.}
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  }
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  \item{max}{number giving the maximum of the color values range.}
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  \item{max}{number giving the maximum of the color values range.}
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  \item{\dots}{further arguments passed to or from other methods.}
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  \item{\dots}{further arguments passed to or from other methods.}
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}
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}
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\details{
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\details{
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  An object of class \code{"raster"} is a matrix of colour values as
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  An object of class \code{"raster"} is a matrix of colour values as
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  It is not expected that the user will need to call these functions
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  It is not expected that the user will need to call these functions
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  directly; functions to render bitmap images in graphics packages will
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  directly; functions to render bitmap images in graphics packages will
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  make use of the \code{as.raster()} function to generate a raster
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  make use of the \code{as.raster()} function to generate a raster
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  object from their input.
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  object from their input.
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  The \code{as.raster()} function is generic so methods can be
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  The \code{as.raster()} function is (S3) generic so methods can be
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  written to convert other R objects to a raster object.
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  written to convert other \R objects to a raster object.
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  The default implementation for numeric matrices interprets scalar
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  The default implementation for numeric matrices interprets scalar
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  values on black-to-white scale.
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  values on black-to-white scale.
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  Raster objects can be subsetted like a matrix and it is
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  Raster objects can be subsetted like a matrix and it is
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  possible to assign to a subset of a raster object.
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  possible to assign to a subset of a raster object.
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  There is a method for converting a raster object to a matrix
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  There is a method for converting a raster object to a
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  (of colour strings).
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  \code{\link{matrix}} (of colour strings).
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  Raster objects can be compared
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  Raster objects can be compared for equality or inequality (with each
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  for equality or inequality (with each other or with a
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  colour string).
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  other or with a colour string).
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  There is a \code{\link{is.na}} method which returns a logical matrix
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  There is a \code{\link{is.na}} method which returns a logical matrix
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  of the same dimensions as the raster object.  Note that \code{NA}
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  of the same dimensions as the raster object.  Note that \code{NA}
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  values are interpreted as the fully transparent colour by some (but
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  values are interpreted as the fully transparent colour by some (but
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  not all) graphics devices.
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  not all) graphics devices.
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# Vectors are 1-column matrices ...
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# Vectors are 1-column matrices ...
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#   character vectors are color names ...
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#   character vectors are color names ...
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as.raster(hcl(0, 80, seq(50, 80, 10)))
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as.raster(hcl(0, 80, seq(50, 80, 10)))
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#   numeric vectors are greyscale ...
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#   numeric vectors are greyscale ...
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as.raster(1:5, max = 5)
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as.raster(1:5, max = 5)
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#   locigal vectors are black and white ...
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#   logical vectors are black and white ...
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as.raster(1:10 \%\% 2 == 0)
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as.raster(1:10 \%\% 2 == 0)
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# ... unless nrow/ncol are supplied ...
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# ... unless nrow/ncol are supplied ...
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as.raster(1:10 \%\% 2 == 0, nrow = 1)
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as.raster(1:10 \%\% 2 == 0, nrow = 1)
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# Matrix can also be logical or numeric ...
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# Matrix can also be logical or numeric (or raw) ...
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as.raster(matrix(c(TRUE, FALSE), nrow = 3, ncol = 2))
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as.raster(matrix(c(TRUE, FALSE), nrow = 3, ncol = 2))
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as.raster(matrix(1:3/4, nrow = 3, ncol = 4))
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as.raster(matrix(1:3/4, nrow = 3, ncol = 4))
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# An array can be 3-plane numeric (R, G, B planes) ...
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# An array can be 3-plane numeric (R, G, B planes) ...
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as.raster(array(c(0:1, rep(0.5, 4)), c(2, 1, 3)))
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as.raster(array(c(0:1, rep(0.5, 4)), c(2, 1, 3)))