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.
Options(options=list(), ...)
options |
A tree |
... |
Not used. |
Note, this class and its methods do not operate on the global options structure defined in R (options).
The constructor returns an Options object.
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
Henrik Bengtsson
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)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.