This library provides the Set class, which deals with a collection of unordered values with no duplicates. It is a hybrid of Array's intuitive inter-operation facilities and Hash's 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 Array's intuitive inter-operation facilities and Hash's 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] #=> #<Set: {1, 2}> s2 = [1, 2].to_set #=> #<Set: {1, 2}> s1 == s2 #=> true s1.add("foo") #=> #<Set: {1, 2, "foo"}> s1.merge([2, 6]) #=> #<Set: {1, 2, "foo", 6}> s1.subset?(s2) #=> false s2.subset?(s1) #=> true
Akinori MUSHA <knu@iDaemons.org> (current maintainer)
First, what's 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.
Creates a new set containing the given objects.
Set[1, 2] # => #<Set: {1, 2}> Set[1, 2, 1] # => #<Set: {1, 2}> Set[1, 'c', :s] # => #<Set: {1, "c", :s}>
# File ruby-3.1.2/lib/set.rb, line 230
def self.[](*ary)
new(ary)
end
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: {1, 2}> Set.new([1, 2, 1]) #=> #<Set: {1, 2}> Set.new([1, 'c', :s]) #=> #<Set: {1, "c", :s}> Set.new(1..5) #=> #<Set: {1, 2, 3, 4, 5}> Set.new([1, 2, 3]) { |x| x * x } #=> #<Set: {1, 4, 9}>
# File ruby-3.1.2/lib/set.rb, line 245
def initialize(enum = nil, &block) # :yields: o
@hash ||= Hash.new(false)
enum.nil? and return
if block
do_with_enum(enum) { |o| add(block[o]) }
else
merge(enum)
end
end
Returns a new set containing elements common to the set and the given enumerable object.
Set[1, 3, 5] & Set[3, 2, 1] #=> #<Set: {3, 1}> Set['a', 'b', 'z'] & ['a', 'b', 'c'] #=> #<Set: {"a", "b"}>
# File ruby-3.1.2/lib/set.rb, line 648
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
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: {3}> Set['a', 'b', 'z'] - ['a', 'c'] #=> #<Set: {"b", "z"}>
# File ruby-3.1.2/lib/set.rb, line 638
def -(enum)
dup.subtract(enum)
end
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.
# File ruby-3.1.2/lib/set.rb, line 463
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
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] #=> true Set[1, 3, 5] == Set[1, 5] #=> false Set['a', 'b', 'c'] == Set['a', 'c', 'b'] #=> true Set['a', 'b', 'c'] == ['a', 'c', 'b'] #=> false
# File ruby-3.1.2/lib/set.rb, line 682
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
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 # => "fruit"
Or by itself:
Set[1, 2, 3] === 2 #=> true Set[1, 2, 3] === 4 #=> false
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: {3, 1}> Set[1, 'b', 'c'] ^ ['b', 'd'] #=> #<Set: {"d", 1, "c"}>
# File ruby-3.1.2/lib/set.rb, line 669
def ^(enum)
n = Set.new(enum)
each { |o| n.add(o) unless n.delete?(o) }
n
end
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, 3}> Set[1, 2].add([3, 4]) #=> #<Set: {1, 2, [3, 4]}> Set[1, 2].add(2) #=> #<Set: {1, 2}>
# File ruby-3.1.2/lib/set.rb, line 521
def add(o)
@hash[o] = true
self
end
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, 3}> Set[1, 2].add?([3, 4]) #=> #<Set: {1, 2, [3, 4]}> Set[1, 2].add?(2) #=> nil
# File ruby-3.1.2/lib/set.rb, line 533
def add?(o)
add(o) unless include?(o)
end
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 #=> {2000=>#<Set: {"a.rb", "b.rb"}>, # 2001=>#<Set: {"c.rb", "d.rb", "e.rb"}>, # 2002=>#<Set: {"f.rb"}>}
Returns an enumerator if no block is given.
# File ruby-3.1.2/lib/set.rb, line 751
def classify # :yields: o
block_given? or return enum_for(__method__) { size }
h = {}
each { |i|
(h[yield(i)] ||= self.class.new).add(i)
}
h
end
Removes all elements and returns self.
set = Set[1, 'c', :s] #=> #<Set: {1, "c", :s}> set.clear #=> #<Set: {}> set #=> #<Set: {}>
# File ruby-3.1.2/lib/set.rb, line 326
def clear
@hash.clear
self
end
Replaces the elements with ones returned by collect(). Returns an enumerator if no block is given.
# File ruby-3.1.2/lib/set.rb, line 574
def collect!
block_given? or return enum_for(__method__) { size }
set = self.class.new
each { |o| set << yield(o) }
replace(set)
end
Makes the set compare its elements by their identity and returns self. This method may not be supported by all subclasses of Set.
# File ruby-3.1.2/lib/set.rb, line 259
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
Returns true if the set will compare its elements by their identity. Also see Set#compare_by_identity.
# File ruby-3.1.2/lib/set.rb, line 270
def compare_by_identity?
@hash.respond_to?(:compare_by_identity?) && @hash.compare_by_identity?
end
Deletes the given object from the set and returns self. Use subtract to delete many items at once.
# File ruby-3.1.2/lib/set.rb, line 539
def delete(o)
@hash.delete(o)
self
end
Deletes the given object from the set and returns self. If the object is not in the set, returns nil.
# File ruby-3.1.2/lib/set.rb, line 546
def delete?(o)
delete(o) if include?(o)
end
Deletes every element of the set for which block evaluates to true, and returns self. Returns an enumerator if no block is given.
# File ruby-3.1.2/lib/set.rb, line 553
def delete_if
block_given? or return enum_for(__method__) { size }
# @hash.delete_if should be faster, but using it breaks the order
# of enumeration in subclasses.
select { |o| yield o }.each { |o| @hash.delete(o) }
self
end
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] #=> false Set[1, 2, 3].disjoint? Set[4, 5] #=> true Set[1, 2, 3].disjoint? [3, 4] #=> false Set[1, 2, 3].disjoint? 4..5 #=> true
# File ruby-3.1.2/lib/set.rb, line 502
def disjoint?(set)
!intersect?(set)
end
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 #=> #<Set: {#<Set: {1}>, # #<Set: {11, 9, 10}>, # #<Set: {3, 4}>, # #<Set: {6}>}>
Returns an enumerator if no block is given.
# File ruby-3.1.2/lib/set.rb, line 779
def divide(&func)
func or return enum_for(__method__) { size }
if func.arity == 2
require 'tsort'
class << dig = {} # :nodoc:
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
Calls the given block once for each element in the set, passing the element as parameter. Returns an enumerator if no block is given.
# File ruby-3.1.2/lib/set.rb, line 509
def each(&block)
block or return enum_for(__method__) { size }
@hash.each_key(&block)
self
end
Returns true if the set contains no elements.
# File ruby-3.1.2/lib/set.rb, line 317
def empty?
@hash.empty?
end
Returns a new set that is a copy of the set, flattening each containing set recursively.
# File ruby-3.1.2/lib/set.rb, line 387
def flatten
self.class.new.flatten_merge(self)
end
Equivalent to Set#flatten, but replaces the receiver with the result in place. Returns nil if no modifications were made.
# File ruby-3.1.2/lib/set.rb, line 393
def flatten!
replace(flatten()) if any? { |e| e.is_a?(Set) }
end
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?
# File ruby-3.1.2/lib/set.rb, line 403
def include?(o)
@hash[o]
end
Clone internal hash.
# File ruby-3.1.2/lib/set.rb, line 293
def initialize_clone(orig, **options)
super
@hash = orig.instance_variable_get(:@hash).clone(**options)
end
Dup internal hash.
# File ruby-3.1.2/lib/set.rb, line 286
def initialize_dup(orig)
super
@hash = orig.instance_variable_get(:@hash).dup
end
Returns a string containing a human-readable representation of the set (“#<Set: {element1, element2, …}>”).
# File ruby-3.1.2/lib/set.rb, line 819
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
Returns true if the set and the given enumerable have at least one element in common.
Set[1, 2, 3].intersect? Set[4, 5] #=> false Set[1, 2, 3].intersect? Set[3, 4] #=> true Set[1, 2, 3].intersect? 4..5 #=> false Set[1, 2, 3].intersect? [3, 4] #=> true
# File ruby-3.1.2/lib/set.rb, line 480
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
Returns a string created by converting each element of the set to a string See also: Array#join
# File ruby-3.1.2/lib/set.rb, line 811
def join(separator=nil)
to_a.join(separator)
end
Deletes every element of the set for which block evaluates to false, and returns self. Returns an enumerator if no block is given.
# File ruby-3.1.2/lib/set.rb, line 564
def keep_if
block_given? or return enum_for(__method__) { size }
# @hash.keep_if should be faster, but using it breaks the order of
# enumeration in subclasses.
reject { |o| yield o }.each { |o| @hash.delete(o) }
self
end
Merges the elements of the given enumerable object to the set and returns self.
# File ruby-3.1.2/lib/set.rb, line 605
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
Returns true if the set is a proper subset of the given set.
# File ruby-3.1.2/lib/set.rb, line 448
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
Returns true if the set is a proper superset of the given set.
# File ruby-3.1.2/lib/set.rb, line 422
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
Equivalent to Set#delete_if, but returns nil if no changes were made. Returns an enumerator if no block is given.
# File ruby-3.1.2/lib/set.rb, line 584
def reject!(&block)
block or return enum_for(__method__) { size }
n = size
delete_if(&block)
self if size != n
end
Replaces the contents of the set with the contents of the given enumerable object and returns self.
set = Set[1, 'c', :s] #=> #<Set: {1, "c", :s}> set.replace([1, 2]) #=> #<Set: {1, 2}> set #=> #<Set: {1, 2}>
# File ruby-3.1.2/lib/set.rb, line 337
def replace(enum)
if enum.instance_of?(self.class)
@hash.replace(enum.instance_variable_get(:@hash))
self
else
do_with_enum(enum) # make sure enum is enumerable before calling clear
clear
merge(enum)
end
end
Resets the internal state after modification to existing elements and returns self.
Elements will be reindexed and deduplicated.
# File ruby-3.1.2/lib/set.rb, line 707
def reset
if @hash.respond_to?(:rehash)
@hash.rehash # This should perform frozenness check.
else
raise FrozenError, "can't modify frozen #{self.class.name}" if frozen?
end
self
end
Equivalent to Set#keep_if, but returns nil if no changes were made. Returns an enumerator if no block is given.
# File ruby-3.1.2/lib/set.rb, line 593
def select!(&block)
block or return enum_for(__method__) { size }
n = size
keep_if(&block)
self if size != n
end
Returns the number of elements.
# File ruby-3.1.2/lib/set.rb, line 311
def size
@hash.size
end
Returns true if the set is a subset of the given set.
# File ruby-3.1.2/lib/set.rb, line 435
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
Deletes every element that appears in the given enumerable object and returns self.
# File ruby-3.1.2/lib/set.rb, line 617
def subtract(enum)
do_with_enum(enum) { |o| delete(o) }
self
end
Returns true if the set is a superset of the given set.
# File ruby-3.1.2/lib/set.rb, line 409
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
Converts the set to an array. The order of elements is uncertain.
Set[1, 2].to_a #=> [1, 2] Set[1, 'c', :s].to_a #=> [1, "c", :s]
# File ruby-3.1.2/lib/set.rb, line 352
def to_a
@hash.keys
end
return the JSON value
# File ruby-3.1.2/ext/json/lib/json/add/set.rb, line 25
def to_json(*args)
as_json.to_json(*args)
end
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.
# File ruby-3.1.2/lib/set.rb, line 361
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
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, 2, 3, 4, 5}> Set[1, 5, 'z'] | (1..6) #=> #<Set: {1, 5, "z", 2, 3, 4, 6}>
# File ruby-3.1.2/lib/set.rb, line 627
def |(enum)
dup.merge(enum)
end