A virtual S4 class to represent a data matrix.

## Arguments

data |
A data vector. |

nrow |
An `integer` value giving the desired number of rows. |

ncol |
An `integer` value giving the desired number of
columns. |

byrow |
A `logical` scalar: should the matrix be filled by
rows? If `FALSE` (the default) the matrix is filled by columns. |

dimnames |
A list of length 2 giving the row and column names
respectively. If `NULL` (the default) dimension names will be created. |

## Slots

`values`

An `integer`

, a `numeric`

or a
`logical`

vector (see details).

## Access

In the code snippets below, `x`

is a `*Matrix`

object.

`length(x)`

Returns the length of `x`

.

`dim(x)`

Returns the dimension of `x`

.

`nrow(x)`

Returns the number of rows present in `x`

.

`ncol(x)`

Returns the number of columns present in `x`

.

`dimnames(x)`

, `dimnames(x) <- value`

Retrieves or sets
the row dimnames of `x`

according to `value`

.

`rownames(x)`

, `rownames(x) <- value`

Retrieves or sets
the row names of `x`

according to `value`

.

`colnames(x)`

, `colnames(x) <- value`

Retrieves or sets
the column names of `x`

according to `value`

.

## Subset

In the code snippets below, `x`

is a `*Matrix`

object.

`x[i, j, ..., drop]`

Extracts elements selected by subscripts
`i`

and `j`

. Indices are `numeric`

or
`character`

vectors or empty (missing) or `NULL`

.
Numeric values are coerced to `integer`

as by
`as.integer`

(and hence truncated towards zero).
Character vectors will be matched to the `dimnames`

of the
object. An empty index (a comma separated blank) indicates that all
entries in that dimension are selected.
Returns an object of the same class as `x`

.

`x[[i]]`

Extracts a single element selected by subscript
`i`

.

## See also

## Author

N. Frerebeau