R: The Options class

Options {R.utils} | R Documentation

## The Options class

### Description

Package: R.utils
Class Options

`Object`
`~~|`
`~~+--``Options`

Directly known subclasses:
Settings

public static class Options
extends Object

A class to set and get either options stored in a `list` tree structure.

Each option has a pathname. The format of a pathname is similar to a (Unix) filesystem pathname, e.g. "graphics/cex". See examples for more details.

### Usage

    Options(options=list(), ...)

### Arguments

`options` | A tree `list` structure of options.
`...` | Not used.

### Details

Note, this class and its methods do not operate on the global options structure defined in R (options).

### Value

The constructor returns an Options object.

### Fields and Methods

Methods:

| `as.character` | Returns a character string version of this object.
| `as.list` | Gets a list representation of the options.
| `equals` | Checks if this object is equal to another Options object.
| `getLeaves` | Gets all (non-list) options in a flat list.
| `getOption` | Gets an option.
| `hasOption` | Checks if an option exists.
| `names` | Gets the full pathname of all (non-list) options.
| `nbrOfOptions` | Gets the number of options set.
| `setOption` | Sets an option.
| `str` | Prints the structure of the options.

Methods inherited from Object:
$, $<-, [[, [[<-, as.character, attach, attachLocally, clearCache, clearLookupCache, clone, detach, equals, extend, finalize, getEnvironment, getFieldModifier, getFieldModifiers, getFields, getInstantiationTime, getStaticInstance, hasField, hashCode, ll, load, names, objectSize, print, save

### Author(s)

Henrik Bengtsson

### Examples

    local <- Options()

    # Query a missing option
    cex <- getOption(local, "graphics/cex")
    cat("graphics/cex =", cex, "\n")  # Returns NULL

    # Query a missing option with default value
    cex <- getOption(local, "graphics/cex", defaultValue=1)
    cat("graphics/cex =", cex, "\n")  # Returns NULL

    # Set option and get previous value
    oldCex <- setOption(local, "graphics/cex", 2)
    cat("previous graphics/cex =", oldCex, "\n")  # Returns NULL

    # Set option again and get previous value
    oldCex <- setOption(local, "graphics/cex", 3)
    cat("previous graphics/cex =", oldCex, "\n")  # Returns 2

    # Query a missing option with default value, which is ignored
    cex <- getOption(local, "graphics/cex", defaultValue=1)
    cat("graphics/cex =", cex, "\n")  # Returns 3

    # Query multiple options with multiple default values
    multi <- getOption(local, c("graphics/cex", "graphics/pch"), c(1,2))
    print(multi);

    # Check existance of multiple options
    has <- hasOption(local, c("graphics/cex", "graphics/pch"))
    print(has);

    # Get a subtree of options
    graphics <- getOption(local, "graphics")
    print(graphics)

    # Get the complete tree of options
    all <- getOption(local)
    print(all)

[Package R.utils version 2.7.0 Index]