R6DS (version 1.1.0)

RSet: The RSet reference class

Description

The RSet reference class implements the data structure set.

Usage

RSet

Format

An object of class R6ClassGenerator of length 24.

Class Method

The class method belongs to the class.

new(equal, ..., collapse=NULL)

The new method creates a new instance of the RSet class containing the values in ... and collapse as its elements.

The argument equal takes a function defining the "=" operation, The function set to equal takes two values of the elements in the set and return a boolean. It can be, for example, of the form

equal <- function(x, y) return(x$num == y$num)

where x and y are values of two elements in the set with the attribute num.

Immutable Methods

The immutable methods do not change the elements of the instance.

has(val)

The method has returns a boolean indicating if the set contains val.

union(rset)

The method union takes another instance rset of the RSet or RDLL class and returns the union of the two sets.

intersection(rset)

The method intersection takes another instance rset of the RSet class and returns the intersection of the two sets.

difference(rset)

The method difference takes another instance rset of the RSet class and returns the difference (current instance minus rset) of the two sets.

subset(rset)

The method subset takes another instance rset of the RSet class. It returns TRUE if the current instance is a subset of rset.

contains(rset)

The method contains takes another instance rset of the RSet or RDLL class. It returns TRUE if the current instance contains rset.

Mutable Methods

The mutable methods changes the elements of the instance.

add(val)

The method add adds a new element and returns TRUE showing that the inserting is successful, but if there is one element in current set that is equal to the element, the method will do nothing and return a FALSE showing that the adding fails.

delete(val)

The method delete removes the element which is equal to val. If the element is found, then it will be removed and the function returns a TRUE, and if the element is not found, then it will do nothing and returns a FALSE,

Details

A set is a collection of items or elements equipped with the "=" operators such that any two elements in the set cannot be equal. The set data structure does not care the order of the elements.

The class RSet inherits the RDLL class, and therefor it has all the methods that RDLL has.

Note that the methods insert_at, appendleft, append in the super class still works without checking if the new element equals any other elements in the set. Normally they should be depreciated in the RSet class, but this is not done in the current version of the package. It is strongly recommended that the user should use the add method to add a new element when using the RSet class.

The elements in the set are not necessarily to be of the same type, and they can even be of function type.

References

For the details about the set data structure, see Set at Wikipedia.

See Also

RDLL and R6DS for the introduction of the reference class and some common methods

Examples

# NOT RUN {
### create a new instance

# you have to define "="
equal <- function(x, y) return(x$key == y$key)
# remember that the elements in the set must have the "key" attribute

# to create a new instance of the class
set <- RSet$new(equal=equal)

# of course you can start to add elements when creating the instance
# the previous RSet instance will be removed by doing so
# and the memory allocated for that one will be cleared,
# as now set has been pointed to another instance of the class.
set <- RSet$new(equal=equal,
    list(key=5, val="5"), collapse=list(list(key=3,val="3"), list(key=9,val="9")))
# the following sentence is equivalent to the above
set <- RSet$new(equal=equal,
    list(key=5, val="5"), list(key=3,val="3"), list(key=9,val="9"))
# where the three lists are inserted into the set

### immutable methods

set$has(list(key=5, num=10))
# TRUE as it has the key attribute

### mutable methods

set$add(list(key=5, num=10))
# FALSE

set$add(list(key=10, val="10"))
# TRUE

set$delete(list(key=10))
# TRUE and list(key=10, val="10") is removed

# union
another_set <- RSet$new(equal=equal,
    list(key=5, val="5"), list(key=11,val="11"))
set$union(another_set)$show()

# intersection
set$intersection(another_set)$show()

# difference
set$difference(another_set)$show()

# subset
set$subset(another_set)

# contains
set$contains(another_set)

# }

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