spam-class {spam} | R Documentation

## Class "spam"

### Description

The `spam` class is a representation of sparse matrices.

### Objects from the Class

Objects can be created by calls of the form `new("spam", entries, colindices, rowpointes, dimension)`. The standard "old Yale sparse format" is used to store sparse matrices.
The matrix `x` is stored in row form. The first element of row `i` is `x@rowpointers[i]`. The length of row `i` is determined by `x@rowpointers[i+1]-x@rowpointers[i]`. The column indices of `x` are stored in the `x@colindices` vector. The column index for element `x@entries[k]` is `x@colindices[k]`.

### Slots

`entries`:

  Object of class `"numeric"` contains the nonzero values.

`colindices`:

  Object of class `"integer"` ordered indices of the nonzero values.

`rowpointers`:

  Object of class `"integer"` pointer to the beginning of each row in the arrays `entries` and `colindices`.

`dimension`:

  Object of class `"integer"` specifying the dimension of the matrix.

### Methods

as.matrix

  `signature(x = "spam")`: transforming a sparse matrix into a regular matrix.

as.vector

  `signature(x = "spam")`: transforming a sparse matrix into a vector (dependings on `structurebased`) see `as.vector.spam` for details.

as.spam

  `signature(x = "spam")`: cleaning of a sparse matrix.

[<-

  `signature(x = "spam", i,j, value)`: assigning a sparse matrix. The negative vectors are not implemented yet.

[

  `signature(x = "spam", i, j)`: subsetting a sparse matrix. The negative vectors are not implemented yet.

%*%

  `signature(x, y)`: matrix multiplication, all combinations of sparse with full matrices or vectors are implemented.

c

  `signature(x = "spam")`: vectorizes the sparse matrix and takes account of the zeros. Hence the lenght of the result is `prod(dim(x))`.

cbind

  `signature(x = "spam")`: binds sparse matrices, see `cbind` for details.

chol

  `signature(x = "spam")`: see `chol` for details.

diag

  `signature(x = "spam")`: see `diag` for details.

dim<-

  `signature(x = "spam")`: rearranges the matrix to reflect a new dimension.

dim

  `signature(x = "spam")`: gives the dimension of the sparse matrix.

pad<-

  `signature(x = "spam")`: truncates or augments the matrix see `dim` for details.

image

  `signature(x = "spam")`: see `image` for details.

display

  `signature(x = "spam")`: see `display` for details.

length<-

  `signature(x = "spam")`: Is not implemented and causes an error.

length

  `signature(x = "spam")`: gives the number of non-zero elements.

lower.tri

  `signature(x = "spam")`: see `lower.tri` for details.

Math

  `signature(x = "spam")`: see `Math` for details.

Math2

  `signature(x = "spam")`: see `Math2` for details.

norm

  `signature(x = "spam")`: calculates the norm of a matrix.

plot

  `signature(x = "spam", y)`: same functionality as the ordinary `plot`.

print

  `signature(x = "spam")`: see `print` for details.

rbind

  `signature(x = "spam")`: binds sparse matrices, see `cbind` for details.

solve

  `signature(a = "spam")`: see `solve` for details.

summary

  `signature(object = "spam")`: small summary statement of the sparse matrix.

Summary

  `signature(x = "spam")`: All functions of the `Summary` class (like `min`, `max`, `range`...) operate on the vector `x@entries` and return the result thereof. See Examples or `Summary` for details.

t

  `signature(x = "spam")`: transpose of a sparse matrix.

upper.tri

  `signature(x = "spam")`: see `lower.tri` for details.

### Details

The compressed sparse row (CSR) format is often described with the vectors `a`, `ia`, `ja`. To be a bit more comprehensive, we have chosen longer slot names.

### Note

The slots `colindices` and `rowpointers` are tested for proper integer assignments. This is not true for `entries`.

### Author(s)

Reinhard Furrer, some of the Fortran code is based on A. George, J. Liu, E. S. Ng, B.W Peyton and Y. Saad (alphabetical)

### Examples

    showMethods("as.spam")

    smat <- diag.spam(runif(15))
    range(smat)
    cos(smat)

[Package spam version 2.2-2 Index]