This library provides the Set class, which deals with a collection of unordered values with no duplicates. It is a hybrid of Arrayâs intuitive inter-operation facilities and Hashâs fast lookup.
The method to_set is added to Enumerable for convenience.
Set implements a collection of unordered values with no duplicates. This is a hybrid of Arrayâs intuitive inter-operation facilities and Hashâs fast lookup.
Set is easy to use with Enumerable objects (implementing each). Most of the initializer methods and binary operators accept generic Enumerable objects besides sets and arrays. An Enumerable object can be converted to Set using the to_set method.
Set uses Hash as storage, so you must note the following points:
Equality of elements is determined according to Object#eql? and Object#hash. Use Set#compare_by_identity to make a set compare its elements by their identity.
Set assumes that the identity of each element does not change while it is stored. Modifying an element of a set will render the set to an unreliable state.
When a string is to be stored, a frozen copy of the string is stored instead unless the original string is already frozen.
The comparison operators <, >, <=, and >= are implemented as shorthand for the {proper_,}{subset?,superset?} methods. The <=> operator reflects this order, or return nil for sets that both have distinct elements ({x, y} vs. {x, z} for example).
require 'set'
s1 = Set[1, 2]
s2 = [1, 2].to_set
s1 == s2
s1.add("foo")
s1.merge([2, 6])
s1.subset?(s2)
s2.subset?(s1)
Akinori MUSHA <knu@iDaemons.org> (current maintainer)
First, whatâs elsewhere. Class Set:
Inherits from class Object.
Includes module Enumerable, which provides dozens of additional methods.
In particular, class Set does not have many methods of its own for fetching or for iterating. Instead, it relies on those in Enumerable.
Here, class Set provides methods that are useful for:
::[] - Returns a new set containing the given objects.
::new - Returns a new set containing either the given objects (if no block given) or the return values from the called block (if a block given).
| (aliased as union and +) - Returns a new set containing all elements from self and all elements from a given enumerable (no duplicates).
& (aliased as intersection) - Returns a new set containing all elements common to self and a given enumerable.
- (aliased as difference) - Returns a copy of self with all elements in a given enumerable removed.
^ - Returns a new set containing all elements from self and a given enumerable except those common to both.
<=> - Returns -1, 0, or 1 as self is less than, equal to, or greater than a given object.
== - Returns whether self and a given enumerable are equal, as determined by Object#eql?.
compare_by_identity? - Returns whether the set considers only identity when comparing elements.
empty? - Returns whether the set has no elements.
include? (aliased as member? and ===) - Returns whether a given object is an element in the set.
subset? (aliased as <=) - Returns whether a given object is a subset of the set.
proper_subset? (aliased as <) - Returns whether a given enumerable is a proper subset of the set.
superset? (aliased as <=]) - Returns whether a given enumerable is a superset of the set.
proper_superset? (aliased as >) - Returns whether a given enumerable is a proper superset of the set.
disjoint? - Returns true if the set and a given enumerable have no common elements, false otherwise.
intersect? - Returns true if the set and a given enumerable - have any common elements, false otherwise.
compare_by_identity? - Returns whether the set considers only identity when comparing elements.
add (aliased as <<) - Adds a given object to the set; returns self.
add? - If the given object is not an element in the set, adds it and returns self; otherwise, returns nil.
merge - Adds each given object to the set; returns self.
replace - Replaces the contents of the set with the contents of a given enumerable.
clear - Removes all elements in the set; returns self.
delete - Removes a given object from the set; returns self.
delete? - If the given object is an element in the set, removes it and returns self; otherwise, returns nil.
subtract - Removes each given object from the set; returns self.
delete_if - Removes elements specified by a given block.
select! (aliased as filter!) - Removes elements not specified by a given block.
keep_if - Removes elements not specified by a given block.
reject! Removes elements specified by a given block.
classify - Returns a hash that classifies the elements, as determined by the given block.
collect! (aliased as map!) - Replaces each element with a block return-value.
divide - Returns a hash that classifies the elements, as determined by the given block; differs from classify in that the block may accept either one or two arguments.
flatten - Returns a new set that is a recursive flattening of self. flatten! - Replaces each nested set in self with the elements from that set.
inspect (aliased as to_s) - Returns a string displaying the elements.
join - Returns a string containing all elements, converted to strings as needed, and joined by the given record separator.
to_a - Returns an array containing all set elements.
to_set - Returns self if given no arguments and no block; with a block given, returns a new set consisting of block return values.
each - Calls the block with each successive element; returns self.
reset - Resets the internal state; useful if an object has been modified while an element in the set.
[](*ary) click to toggle source
Creates a new set containing the given objects.
Set[1, 2] Set[1, 2, 1] Set[1, 'c', :s]
def self.[](*ary) new(ary) end
json_create(object) click to toggle source
Import a JSON Marshalled object.
method used for JSON marshalling support.
def self.json_create(object) new object['a'] end
new(enum = nil) { |o| ... } click to toggle source
Creates a new set containing the elements of the given enumerable object.
If a block is given, the elements of enum are preprocessed by the given block.
Set.new([1, 2])
Set.new([1, 2, 1])
Set.new([1, 'c', :s])
Set.new(1..5)
Set.new([1, 2, 3]) { |x| x * x }
def initialize(enum = nil, &block)
@hash ||= Hash.new(false)
enum.nil? and return
if block
do_with_enum(enum) { |o| add(block[o]) }
else
merge(enum)
end
end Public Instance Methods
&(enum) click to toggle source
Returns a new set containing elements common to the set and the given enumerable object.
Set[1, 3, 5] & Set[3, 2, 1] Set['a', 'b', 'z'] & ['a', 'b', 'c']
def &(enum)
n = self.class.new
if enum.is_a?(Set)
if enum.size > size
each { |o| n.add(o) if enum.include?(o) }
else
enum.each { |o| n.add(o) if include?(o) }
end
else
do_with_enum(enum) { |o| n.add(o) if include?(o) }
end
n
end
-(enum) click to toggle source
Returns a new set built by duplicating the set, removing every element that appears in the given enumerable object.
Set[1, 3, 5] - Set[1, 5] Set['a', 'b', 'z'] - ['a', 'c']
def -(enum) dup.subtract(enum) end
<=>(set) click to toggle source
Returns 0 if the set are equal, -1 / +1 if the set is a proper subset / superset of the given set, or nil if they both have unique elements.
def <=>(set) return unless set.is_a?(Set) case size <=> set.size when -1 then -1 if proper_subset?(set) when +1 then +1 if proper_superset?(set) else 0 if self.==(set) end end
==(other) click to toggle source
Returns true if two sets are equal. The equality of each couple of elements is defined according to Object#eql?.
Set[1, 2] == Set[2, 1] Set[1, 3, 5] == Set[1, 5] Set['a', 'b', 'c'] == Set['a', 'c', 'b'] Set['a', 'b', 'c'] == ['a', 'c', 'b']
def ==(other)
if self.equal?(other)
true
elsif other.instance_of?(self.class)
@hash == other.instance_variable_get(:@hash)
elsif other.is_a?(Set) && self.size == other.size
other.all? { |o| @hash.include?(o) }
else
false
end
end
===(o)
Returns true if the given object is a member of the set, and false otherwise.
Used in case statements:
require 'set' case :apple when Set[:potato, :carrot] "vegetable" when Set[:apple, :banana] "fruit" end
Or by itself:
Set[1, 2, 3] === 2 Set[1, 2, 3] === 4
^(enum) click to toggle source
Returns a new set containing elements exclusive between the set and the given enumerable object. (set ^ enum) is equivalent to ((set | enum) - (set & enum)).
Set[1, 2] ^ Set[2, 3] Set[1, 'b', 'c'] ^ ['b', 'd']
def ^(enum)
n = Set.new(enum)
each { |o| n.add(o) unless n.delete?(o) }
n
end
add(o) click to toggle source
Adds the given object to the set and returns self. Use merge to add many elements at once.
Set[1, 2].add(3) Set[1, 2].add([3, 4]) Set[1, 2].add(2)
def add(o) @hash[o] = true self end
add?(o) click to toggle source
Adds the given object to the set and returns self. If the object is already in the set, returns nil.
Set[1, 2].add?(3) Set[1, 2].add?([3, 4]) Set[1, 2].add?(2)
def add?(o) add(o) unless include?(o) end
as_json(*) click to toggle source
method used for JSON marshalling support.
def as_json(*)
{
JSON.create_id => self.class.name,
'a' => to_a,
}
end
classify() { |o| ... } click to toggle source
Classifies the set by the return value of the given block and returns a hash of {value => set of elements} pairs. The block is called once for each element of the set, passing the element as parameter.
require 'set'
files = Set.new(Dir.glob("*.rb"))
hash = files.classify { |f| File.mtime(f).year }
hash
Returns an enumerator if no block is given.
def classify
block_given? or return enum_for(__method__) { size }
h = {}
each { |i|
(h[yield(i)] ||= self.class.new).add(i)
}
h
end
clear() click to toggle source
Removes all elements and returns self.
set = Set[1, 'c', :s] set.clear set
def clear @hash.clear self end
collect!() { |o| ... } click to toggle source
Replaces the elements with ones returned by collect(). Returns an enumerator if no block is given.
def collect!
block_given? or return enum_for(__method__) { size }
set = self.class.new
each { |o| set << yield(o) }
replace(set)
end
compare_by_identity() click to toggle source
Makes the set compare its elements by their identity and returns self. This method may not be supported by all subclasses of Set.
def compare_by_identity
if @hash.respond_to?(:compare_by_identity)
@hash.compare_by_identity
self
else
raise NotImplementedError, "#{self.class.name}\##{__method__} is not implemented"
end
end
compare_by_identity?() click to toggle source
Returns true if the set will compare its elements by their identity. Also see Set#compare_by_identity.
def compare_by_identity? @hash.respond_to?(:compare_by_identity?) && @hash.compare_by_identity? end
delete(o) click to toggle source
Deletes the given object from the set and returns self. Use subtract to delete many items at once.
def delete(o) @hash.delete(o) self end
delete?(o) click to toggle source
Deletes the given object from the set and returns self. If the object is not in the set, returns nil.
def delete?(o) delete(o) if include?(o) end
delete_if() { |o| ... } click to toggle source
Deletes every element of the set for which block evaluates to true, and returns self. Returns an enumerator if no block is given.
def delete_if
block_given? or return enum_for(__method__) { size }
select { |o| yield o }.each { |o| @hash.delete(o) }
self
end
disjoint?(set) click to toggle source
Returns true if the set and the given enumerable have no element in common. This method is the opposite of intersect?.
Set[1, 2, 3].disjoint? Set[3, 4] Set[1, 2, 3].disjoint? Set[4, 5] Set[1, 2, 3].disjoint? [3, 4] Set[1, 2, 3].disjoint? 4..5
def disjoint?(set) !intersect?(set) end
divide(&func) click to toggle source
Divides the set into a set of subsets according to the commonality defined by the given block.
If the arity of the block is 2, elements o1 and o2 are in common if block.call(o1, o2) is true. Otherwise, elements o1 and o2 are in common if block.call(o1) == block.call(o2).
require 'set'
numbers = Set[1, 3, 4, 6, 9, 10, 11]
set = numbers.divide { |i,j| (i - j).abs == 1 }
set
Returns an enumerator if no block is given.
def divide(&func)
func or return enum_for(__method__) { size }
if func.arity == 2
require 'tsort'
class << dig = {}
include TSort
alias tsort_each_node each_key
def tsort_each_child(node, &block)
fetch(node).each(&block)
end
end
each { |u|
dig[u] = a = []
each{ |v| func.call(u, v) and a << v }
}
set = Set.new()
dig.each_strongly_connected_component { |css|
set.add(self.class.new(css))
}
set
else
Set.new(classify(&func).values)
end
end
each(&block) click to toggle source
Calls the given block once for each element in the set, passing the element as parameter. Returns an enumerator if no block is given.
def each(&block)
block or return enum_for(__method__) { size }
@hash.each_key(&block)
self
end
empty?() click to toggle source
Returns true if the set contains no elements.
def empty? @hash.empty? end
flatten() click to toggle source
Returns a new set that is a copy of the set, flattening each containing set recursively.
def flatten self.class.new.flatten_merge(self) end
flatten!() click to toggle source
Equivalent to Set#flatten, but replaces the receiver with the result in place. Returns nil if no modifications were made.
def flatten!
replace(flatten()) if any? { |e| e.is_a?(Set) }
end
include?(o) click to toggle source
Returns true if the set contains the given object.
Note that include? and member? do not test member equality using == as do other Enumerables.
See also Enumerable#include?
def include?(o) @hash[o] end
initialize_clone(orig, **options) click to toggle source
Clone internal hash.
Calls superclass method
def initialize_clone(orig, **options) super @hash = orig.instance_variable_get(:@hash).clone(**options) end
initialize_dup(orig) click to toggle source
Dup internal hash.
Calls superclass method
def initialize_dup(orig) super @hash = orig.instance_variable_get(:@hash).dup end
inspect() click to toggle source
Returns a string containing a human-readable representation of the set (â#<Set: {element1, element2, â¦}>â).
def inspect
ids = (Thread.current[InspectKey] ||= [])
if ids.include?(object_id)
return sprintf('#<%s: {...}>', self.class.name)
end
ids << object_id
begin
return sprintf('#<%s: {%s}>', self.class, to_a.inspect[1..-2])
ensure
ids.pop
end
end
intersect?(set) click to toggle source
Returns true if the set and the given enumerable have at least one element in common.
Set[1, 2, 3].intersect? Set[4, 5] Set[1, 2, 3].intersect? Set[3, 4] Set[1, 2, 3].intersect? 4..5 Set[1, 2, 3].intersect? [3, 4]
def intersect?(set)
case set
when Set
if size < set.size
any? { |o| set.include?(o) }
else
set.any? { |o| include?(o) }
end
when Enumerable
set.any? { |o| include?(o) }
else
raise ArgumentError, "value must be enumerable"
end
end
join(separator=nil) click to toggle source
Returns a string created by converting each element of the set to a string See also: Array#join
def join(separator=nil) to_a.join(separator) end
keep_if() { |o| ... } click to toggle source
Deletes every element of the set for which block evaluates to false, and returns self. Returns an enumerator if no block is given.
def keep_if
block_given? or return enum_for(__method__) { size }
reject { |o| yield o }.each { |o| @hash.delete(o) }
self
end
merge(enum) click to toggle source
Merges the elements of the given enumerable object to the set and returns self.
def merge(enum)
if enum.instance_of?(self.class)
@hash.update(enum.instance_variable_get(:@hash))
else
do_with_enum(enum) { |o| add(o) }
end
self
end
proper_subset?(set) click to toggle source
Returns true if the set is a proper subset of the given set.
def proper_subset?(set)
case
when set.instance_of?(self.class) && @hash.respond_to?(:<)
@hash < set.instance_variable_get(:@hash)
when set.is_a?(Set)
size < set.size && all? { |o| set.include?(o) }
else
raise ArgumentError, "value must be a set"
end
end
proper_superset?(set) click to toggle source
Returns true if the set is a proper superset of the given set.
def proper_superset?(set)
case
when set.instance_of?(self.class) && @hash.respond_to?(:>)
@hash > set.instance_variable_get(:@hash)
when set.is_a?(Set)
size > set.size && set.all? { |o| include?(o) }
else
raise ArgumentError, "value must be a set"
end
end
reject!(&block) click to toggle source
Equivalent to Set#delete_if, but returns nil if no changes were made. Returns an enumerator if no block is given.
def reject!(&block)
block or return enum_for(__method__) { size }
n = size
delete_if(&block)
self if size != n
end
replace(enum) click to toggle source
Replaces the contents of the set with the contents of the given enumerable object and returns self.
set = Set[1, 'c', :s] set.replace([1, 2]) set
def replace(enum)
if enum.instance_of?(self.class)
@hash.replace(enum.instance_variable_get(:@hash))
self
else
do_with_enum(enum)
clear
merge(enum)
end
end
reset() click to toggle source
Resets the internal state after modification to existing elements and returns self.
Elements will be reindexed and deduplicated.
def reset
if @hash.respond_to?(:rehash)
@hash.rehash
else
raise FrozenError, "can't modify frozen #{self.class.name}" if frozen?
end
self
end
select!(&block) click to toggle source
Equivalent to Set#keep_if, but returns nil if no changes were made. Returns an enumerator if no block is given.
def select!(&block)
block or return enum_for(__method__) { size }
n = size
keep_if(&block)
self if size != n
end
size() click to toggle source
Returns the number of elements.
subset?(set) click to toggle source
Returns true if the set is a subset of the given set.
def subset?(set)
case
when set.instance_of?(self.class) && @hash.respond_to?(:<=)
@hash <= set.instance_variable_get(:@hash)
when set.is_a?(Set)
size <= set.size && all? { |o| set.include?(o) }
else
raise ArgumentError, "value must be a set"
end
end
subtract(enum) click to toggle source
Deletes every element that appears in the given enumerable object and returns self.
def subtract(enum)
do_with_enum(enum) { |o| delete(o) }
self
end
superset?(set) click to toggle source
Returns true if the set is a superset of the given set.
def superset?(set)
case
when set.instance_of?(self.class) && @hash.respond_to?(:>=)
@hash >= set.instance_variable_get(:@hash)
when set.is_a?(Set)
size >= set.size && set.all? { |o| include?(o) }
else
raise ArgumentError, "value must be a set"
end
end
to_a() click to toggle source
Converts the set to an array. The order of elements is uncertain.
Set[1, 2].to_a Set[1, 'c', :s].to_a
to_json(*args) click to toggle source
return the JSON value
def to_json(*args) as_json.to_json(*args) end
to_set(klass = Set, *args, &block) click to toggle source
Returns self if no arguments are given. Otherwise, converts the set to another with klass.new(self, *args, &block).
In subclasses, returns klass.new(self, *args, &block) unless overridden.
def to_set(klass = Set, *args, &block) return self if instance_of?(Set) && klass == Set && block.nil? && args.empty? klass.new(self, *args, &block) end
|(enum) click to toggle source
Returns a new set built by merging the set and the elements of the given enumerable object.
Set[1, 2, 3] | Set[2, 4, 5] Set[1, 5, 'z'] | (1..6)
def |(enum) dup.merge(enum) end
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