The R Project SVN R

Rev

Rev 61168 | Rev 64662 | Go to most recent revision | Show entire file | Ignore whitespace | Details | Blame | Last modification | View Log | RSS feed

Rev 61168 Rev 61433
Line 35... Line 35...
35 
  \item{\dots}{further arguments passed to or from other methods.}
 35 
  \item{\dots}{further arguments passed to or from other methods.}
36 
}
 36 
}
37 
\details{
 37 
\details{
38 
  An object of class \code{"raster"} is a matrix of colour values as
 38 
  An object of class \code{"raster"} is a matrix of colour values as
39 
  given by \code{\link{rgb}} representing a bitmap image.
 39 
  given by \code{\link{rgb}} representing a bitmap image.
40
40 
 
41 
  It is not expected that the user will need to call these functions
 41 
  It is not expected that the user will need to call these functions
42 
  directly; functions to render bitmap images in graphics packages will
 42 
  directly; functions to render bitmap images in graphics packages will
43 
  make use of the \code{as.raster()} function to generate a raster
 43 
  make use of the \code{as.raster()} function to generate a raster
44 
  object from their input.
 44 
  object from their input.
45 
 
 45 
 
46 
  The \code{as.raster()} function is generic so methods can be
 46 
  The \code{as.raster()} function is generic so methods can be
47 
  written to convert other R objects to a raster object.
 47 
  written to convert other R objects to a raster object.
48 
 
 48 
 
49 
  The default implementation for numeric matrices interprets scalar
 49 
  The default implementation for numeric matrices interprets scalar
50 
  values on black-to-white scale.
 50 
  values on black-to-white scale.
51
51 
 
52 
  Raster objects can be subsetted like a matrix and it is
 52 
  Raster objects can be subsetted like a matrix and it is
53 
  possible to assign to a subset of a raster object.
 53 
  possible to assign to a subset of a raster object.
54 
 
 54 
 
55 
  There is a method for converting a raster object to a matrix
 55 
  There is a method for converting a raster object to a matrix
56 
  (of colour strings).
 56 
  (of colour strings).
57
57 
 
58 
  Raster objects can be compared
 58 
  Raster objects can be compared
59 
  for equality or inequality (with each other or with a
 59 
  for equality or inequality (with each other or with a
60 
  colour string).
 60 
  colour string).
61
61 
 
62 
  As from \R 2.14.0 there is a \code{\link{is.na}} method which returns
 62 
  As from \R 2.14.0 there is a \code{\link{is.na}} method which returns
63 
  a logical matrix of the same dimensions as the raster object.  Note
 63 
  a logical matrix of the same dimensions as the raster object.  Note
64 
  that \code{NA} values are interpreted as the fully transparent colour
 64 
  that \code{NA} values are interpreted as the fully transparent colour
65 
  by some (but not all) graphics devices.
 65 
  by some (but not all) graphics devices.
66 
}
 66 
}