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: rll{ 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, clone, detach, equals, extend, finalize, gc, getEnvironment, getFields, getInstanciationTime, getStaticInstance, hasField, hashCode, ll, load, objectSize, print, save

Details

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

Examples

Run this code

local <- Options()

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

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

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

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

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