sparse.model.matrix

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Construct Sparse Design / Model Matrices

Construct a Model or Design Matrix

Keywords
models
Usage
sparse.model.matrix(object, data = environment(object),
                    contrasts.arg = NULL, xlev = NULL, ...)
Arguments
object
an object of an appropriate class. For the default method, a model formula or terms object.
data
a data frame created with model.frame. If another sort of object, model.frame is called first.
contrasts.arg
A list, whose entries are contrasts suitable for input to the contrasts replacement function and whose names are the names of columns of data containing
xlev
to be used as argument of model.frame if data has no "terms" attribute.
...
further arguments passed to or from other methods.
Value

  • a sparse matrix, inheriting from CsparseMatrix, typically of class dgCMatrix.

See Also

model.matrix, ...

Aliases
  • sparse.model.matrix
Examples
dd <- data.frame(a = gl(3,4), b = gl(4,1,12))# balanced 2-way
options("contrasts") # the default:  "contr.treatment"
sparse.model.matrix(~ a + b, dd)
sparse.model.matrix(~ -1+ a + b, dd)# no intercept --> even sparse
sparse.model.matrix(~ a + b, dd, contrasts = list(a="contr.sum"))
sparse.model.matrix(~ a + b, dd, contrasts = list(b="contr.SAS"))

## Sparse method is equivalent to the traditional one :
stopifnot(all(sparse.model.matrix(~ a + b, dd) ==
	      Matrix(model.matrix(~ a + b, dd), sparse=TRUE)),
          all(sparse.model.matrix(~ 0+ a + b, dd) ==
	      Matrix(model.matrix(~ 0+ a + b, dd), sparse=TRUE)))
Documentation reproduced from package Matrix, version 0.999375-3, License: GPL version 2 or later. This R package includes libraries CHOLMOD, AMD, COLAMD and CSparse from the University of Florida sparse matrix library maintained by Tim Davis. All sections of that code are covered by the GPL or LGPL licenses. See the directory doc/UFsparse for details.

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