matrix {base} | R Documentation |

`matrix`

creates a matrix from the given set of values.

`as.matrix`

attempts to turn its argument into a matrix.

`is.matrix`

tests if its argument is a (strict) matrix.

matrix(data = NA, nrow = 1, ncol = 1, byrow = FALSE, dimnames = NULL) as.matrix(x, ...) ## S3 method for class 'data.frame': as.matrix(x, rownames.force = NA, ...) is.matrix(x)

`data` |
an optional data vector. |

`nrow` |
the desired number of rows. |

`ncol` |
the desired number of columns. |

`byrow` |
logical. If `FALSE` (the default) the matrix is
filled by columns, otherwise the matrix is filled by rows. |

`dimnames` |
A `dimnames` attribute for the matrix: a
`list` of length 2 giving the row and column names respectively. |

`x` |
an R object. |

`...` |
additional arguments to be passed to or from methods. |

`rownames.force` |
logical indicating if the resulting matrix
should have character (rather than `NULL` )
`rownames` . The default, `NA` , uses `NULL`
rownames if the data frame has ‘automatic’ row.names or for a
zero-row data frame. |

If either of `nrow`

or `ncol`

is not given, an attempt is
made to infer it from the length of `data`

and the other
parameter.

If there are too few elements in `data`

to fill the array,
then the elements in `data`

are recycled. If `data`

has
length zero, `NA`

of an appropriate type is used for atomic
vectors (`0`

for raw vectors) and `NULL`

for lists.

`is.matrix`

returns `TRUE`

if `x`

is a matrix and has a
`dim`

attribute of length 2) and `FALSE`

otherwise.
Note that a `data.frame`

is **not** a matrix by this
test. It is generic: you can write methods to handle
specific classes of objects, see InternalMethods.

`as.matrix`

is a generic function. The method for data frames
will return a character matrix if there is any
non-(numeric/logical/complex) column, applying `format`

to
non-character columns. Otherwise, the usual coercion hierarchy
(logical < integer < double < complex) will be used, e.g., all-logical
data frames will be coerced to a logical matrix, mixed logical-integer
will give a integer matrix, etc.

When coercing a vector, it produces a one-column matrix, and promotes the names (if any) of the vector to the rownames of the matrix.

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
*The New S Language*.
Wadsworth & Brooks/Cole.

`data.matrix`

, which attempts to convert to a numeric matrix.

is.matrix(as.matrix(1:10)) !is.matrix(warpbreaks)# data.frame, NOT matrix! warpbreaks[1:10,] as.matrix(warpbreaks[1:10,]) #using as.matrix.data.frame(.) method # Example of setting row and column names mdat <- matrix(c(1,2,3, 11,12,13), nrow = 2, ncol=3, byrow=TRUE, dimnames = list(c("row1", "row2"), c("C.1", "C.2", "C.3"))) mdat

[Package *base* version 2.5.0 Index]