marginSumsSparse {spatstat.sparse}

Margin Sums of a Sparse Matrix or Sparse Array

Description

For a sparse matrix or sparse array, compute the sum of array entries for a specified margin or margins.

Usage

marginSumsSparse(X, MARGIN)

Arguments

X

A matrix, an array, a sparse matrix (of class "sparseMatrix" from the Matrix package) or a sparse three-dimensional array (of class "sparse3Darray" from the spatstat.sparse package).

MARGIN

Integer or integer vector specifying the margin or margins.

Details

This function computes the equivalent of apply(X, MARGIN, sum) for sparse matrices and arrays X. The argument X may be

• a matrix

• an array of any number of dimensions

• a sparse matrix (object inheriting class "sparseMatrix" in the Matrix package)

• a sparse three-dimensional array (of class "sparse3Darray" from the spatstat.sparse package).

In the first two cases, the computation is performed by calling apply(X, MARGIN, sum) and the result is a vector, matrix or array. In the last two cases, the result is a single value, a sparse vector, a sparse matrix, or a sparse three-dimensional array.

Value

A single value, vector, matrix, array, sparse vector (class "sparseVector" in the Matrix package), sparse matrix (class "sparseMatrix" in the Matrix package), or sparse three-dimensional array (class "sparse3Darray" from the spatstat.sparse package).

Author(s)

Adrian Baddeley [e-mail], Rolf Turner [e-mail] and Ege Rubak [e-mail].

See Also

apply

Examples

  M <- sparse3Darray(i=1:3, j=c(3,1,2), k=4:2,
                     x=round(runif(3), 2), dims=rep(4, 3))
  marginSumsSparse(M, 1:2)
  marginSumsSparse(M, 1)
  marginSumsSparse(M, integer(0)) # equivalent to sum(M)