matter_fc-class {matter} | R Documentation

## Factors Stored on Disk

### Description

The `matter_fc` class implements on-disk factors.

### Usage

    ## Instance creation
    matter_fc(data, datamode = "int", paths = NULL,
                filemode = ifelse(all(file.exists(paths)), "rb", "rb+"),
                offset = 0, extent = length, length = 0L, names = NULL,
                levels = base::levels(as.factor(data)), ...)

    ## Additional methods documented below

### Arguments

`data` | An optional data vector which will be initially written to the data on disk if provided.
`datamode` | Must be an integral type for factors.
`paths` | A 'character' vector of the paths to the files where the data are stored. If 'NULL', then a temporary file is created using `tempfile`.
`filemode` | The read/write mode of the files where the data are stored. This should be 'rb' for read-only access, or 'rb+' for read/write access.
`offset` | A vector giving the offsets in number of bytes from the beginning of each file in 'paths', specifying the start of the data to be accessed for each file.
`extent` | A vector giving the length of the data for each file in 'paths', specifying the number of elements of size 'datamode' to be accessed from each file.
`length` | An optional number giving the total length of the data across all files, equal to the sum of 'extent'. This is ignored and calculated automatically if 'extent' is specified.
`names` | The names of the data elements.
`levels` | The levels of the factor.
`...` | Additional arguments to be passed to constructor.

### Value

An object of class `matter_fc`.

### Slots

`data`:

  This slot stores the information about locations of the data on disk and within the files.

`datamode`:

  The storage mode of the accessed data when read into R. This is a 'character' vector of length one with value 'integer' or 'numeric'.

`paths`:

  A 'character' vector of the paths to the files where the data are stored.

`filemode`:

  The read/write mode of the files where the data are stored. This should be 'rb' for read-only access, or 'rb+' for read/write access.

`chunksize`:

  The maximum number of elements which should be loaded into memory at once. Used by methods implementing summary statistics and linear algebra. Ignored when explicitly subsetting the dataset.

`length`:

  The length of the data.

`dim`:

  Either 'NULL' for vectors, or an integer vector of length one of more giving the maximal indices in each dimension for matrices and arrays.

`names`:

  The names of the data elements for vectors.

`dimnames`:

  Either 'NULL' or the names for the dimensions. If not 'NULL', then this should be a list of character vectors of the length given by 'dim' for each dimension. This is always 'NULL' for vectors.

`ops`:

  Delayed operations to be applied on atoms.

`levels`:

  The levels of the factor.

### Extends

`matter`, `matter_vec`

### Creating Objects

`matter_fc` instances can be created through `matter_fc()` or `matter()`.

### Methods

Standard generic methods:

`x[i], x[i] <- value`:

  Get or set the elements of the factor.

`levels(x), levels(x) <- value`:

  Get or set the levels of the factor.

### Author(s)

Kylie A. Bemis

### See Also

`matter`, `matter_vec`

### Examples

    x <- matter_fc(c("a", "a", "b"), levels=c("a", "b", "c"))
    x[]

[Package matter version 1.6.0 Index]