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?andObject#hash. -
Setassumes 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.
Comparison
The comparison operators <, >, <= and >= are implemented as shorthand for the {proper_,}{subset?,superset?} methods. However, the <=> operator is intentionally left out because not every pair of sets is comparable. ({x,y} vs. {x,z} for example)
Example
require 'set' s1 = Set.new [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
Contact
- Akinori MUSHA <knu@iDaemons.org> (current maintainer)
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 73
def self.[](*ary)
new(ary)
end
Creates a new set containing the given objects.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 82
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
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.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 418
def &(enum)
n = self.class.new
do_with_enum(enum) { |o| n.add(o) if include?(o) }
n
end
Returns a new set containing elements common to the set and the given enumerable object.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 411
def -(enum)
dup.subtract(enum)
end
Returns a new set built by duplicating the set, removing every element that appears in the given enumerable object.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 436
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 two sets are equal. The equality of each couple of elements is defined according to Object#eql?.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 428
def ^(enum)
n = Set.new(enum)
each { |o| n.add(o) unless n.delete?(o) }
n
end
Returns a new set containing elements exclusive between the set and the given enumerable object. (set ^ enum) is equivalent to ((set | enum) - (set & enum)).
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 312
def add(o)
@hash[o] = true
self
end
Adds the given object to the set and returns self. Use merge to add many elements at once.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 320
def add?(o)
add(o) unless include?(o)
end
Adds the given object to the set and returns self. If the object is already in the set, returns nil.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 470
def classify # :yields: o
block_given? or return enum_for(__method__)
h = {}
each { |i|
(h[yield(i)] ||= self.class.new).add(i)
}
h
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.
e.g.:
require 'set' files = Set.new(Dir.glob("*.rb")) hash = files.classify { |f| File.mtime(f).year } p hash # => {2000=>#<Set: {"a.rb", "b.rb"}>, # 2001=>#<Set: {"c.rb", "d.rb", "e.rb"}>, # 2002=>#<Set: {"f.rb"}>}
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 144
def clear
@hash.clear
self
end
Removes all elements and returns self.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 358
def collect!
block_given? or return enum_for(__method__)
replace(self.class.new(self) { |o| yield(o) })
end
Replaces the elements with ones returned by collect().
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 326
def delete(o)
@hash.delete(o)
self
end
Deletes the given object from the set and returns self. Use subtract to delete many items at once.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 333
def delete?(o)
delete(o) if include?(o)
end
Deletes the given object from the set and returns self. If the object is not in the set, returns nil.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 339
def delete_if
block_given? or return enum_for(__method__)
# @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
Deletes every element of the set for which block evaluates to true, and returns self.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 297
def disjoint?(set)
!intersect?(set)
end
Returns true if the set and the given set have no element in common. This method is the opposite of intersect?.
e.g.:
require 'set' Set[1, 2, 3].disjoint? Set[3, 4] # => false Set[1, 2, 3].disjoint? Set[4, 5] # => true
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 498
def divide(&func)
func or return enum_for(__method__)
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
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).
e.g.:
require 'set' numbers = Set[1, 3, 4, 6, 9, 10, 11] set = numbers.divide { |i,j| (i - j).abs == 1 } p set # => #<Set: {#<Set: {1}>, # #<Set: {11, 9, 10}>, # #<Set: {3, 4}>, # #<Set: {6}>}>
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 304
def each(&block)
block or return enum_for(__method__) { size }
@hash.each_key(&block)
self
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 tmp/rubies/ruby-2.3.8/lib/set.rb, line 139
def empty?
@hash.empty?
end
Returns true if the set contains no elements.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 198
def flatten
self.class.new.flatten_merge(self)
end
Returns a new set that is a copy of the set, flattening each containing set recursively.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 204
def flatten!
replace(flatten()) if any? { |e| e.is_a?(Set) }
end
Equivalent to Set#flatten, but replaces the receiver with the result in place. Returns nil if no modifications were made.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 214
def include?(o)
@hash[o]
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 tmp/rubies/ruby-2.3.8/lib/set.rb, line 112
def initialize_clone(orig)
super
@hash = orig.instance_variable_get(:@hash).clone
end
Clone internal hash.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 106
def initialize_dup(orig)
super
@hash = orig.instance_variable_get(:@hash).dup
end
Dup internal hash.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 532
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 a string containing a human-readable representation of the set. (“#<Set: {element1, element2, …}>”)
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 279
def intersect?(set)
set.is_a?(Set) or raise ArgumentError, "value must be a set"
if size < set.size
any? { |o| set.include?(o) }
else
set.any? { |o| include?(o) }
end
end
Returns true if the set and the given set have at least one element in common.
e.g.:
require 'set' Set[1, 2, 3].intersect? Set[4, 5] # => false Set[1, 2, 3].intersect? Set[3, 4] # => true
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 349
def keep_if
block_given? or return enum_for(__method__)
# @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
Deletes every element of the set for which block evaluates to false, and returns self.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 384
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
Merges the elements of the given enumerable object to the set and returns self.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 259
def proper_subset?(set)
case
when set.instance_of?(self.class)
@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 subset of the given set.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 233
def proper_superset?(set)
case
when set.instance_of?(self.class)
@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
Returns true if the set is a proper superset of the given set.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 366
def reject!(&block)
block or return enum_for(__method__)
n = size
delete_if(&block)
self if size != n
end
Equivalent to Set#delete_if, but returns nil if no changes were made.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 151
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
Replaces the contents of the set with the contents of the given enumerable object and returns self.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 375
def select!(&block)
block or return enum_for(__method__)
n = size
keep_if(&block)
self if size != n
end
Equivalent to Set#keep_if, but returns nil if no changes were made.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 133
def size
@hash.size
end
Returns the number of elements.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 246
def subset?(set)
case
when set.instance_of?(self.class)
@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 subset of the given set.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 396
def subtract(enum)
do_with_enum(enum) { |o| delete(o) }
self
end
Deletes every element that appears in the given enumerable object and returns self.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 220
def superset?(set)
case
when set.instance_of?(self.class)
@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
Returns true if the set is a superset of the given set.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 163
def to_a
@hash.keys
end
Converts the set to an array. The order of elements is uncertain.
# File tmp/rubies/ruby-2.3.8/lib/set.rb, line 172
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 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 tmp/rubies/ruby-2.3.8/lib/set.rb, line 403
def |(enum)
dup.merge(enum)
end
Returns a new set built by merging the set and the elements of the given enumerable object.