R.utils (version 2.5.0)

Options: 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.

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

Details

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

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)

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