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