Options
The Options class
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.
- Keywords
- classes, programming
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, gc, getEnvironment, getFieldModifier, getFieldModifiers, getFields, getInstantiationTime, getStaticInstance, hasField, hashCode, ll, load, objectSize, print, save
Examples
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)