RSet: The RSet reference class

In R6DS: R6 Reference Class Based Data Structures

Description

The RSet reference class implements the data structure set.

Usage

RSet

Format

An object of class R6ClassGenerator of length 24.

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.

It should be noticed that, in your design, if any two elements in the set can be easily compared, by simply, for example, keys, numbers, and etc., the RSet should not be recommended due to efficiency reason. The RSet is suitable for the cases when you have a relatively complex "=" operation between two elements in the set.

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 be any R objects.

References

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

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 merges the elements in rset, an instance of some class in the package, with its elements, and returns a new union set of the two.

intersection(rset)

The method intersection returns a new intersection set (RSet) of the current set and rset, an instance of some class in the package.

difference(rset)

The method difference returns a new difference set (RSet) of the current set and rset, an instance of some class in the package (current instance minus rset).

subset(rset)

The method subset returns a boolean indicating if the current set is a subset of rset, an instance of some class in the package.

contains(rset)

The method contains returns a boolean indicating if the current set contains rset, an instance of some class in the package.

Mutable Methods

The mutable methods change the instance.

add(val)

The method add adds a new element into the set and returns a booleank showing if the insertion is successful.

add_multiple(..., collapse=NULL)

The method add_multiple adds new elements in ... and collapse into the set.

delete(val)

The method delete removes the element which is equal to val in the set. It returns a boolean showing if the deletion is successful (if the element is not found in the set).

Author(s)

Yukai Yang, [e-mail]

See Also

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

Examples

### 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
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)

R6DS documentation built on May 21, 2019, 5:04 p.m.