class Set
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.
-
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.
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 <[email protected]> (current maintainer)
Public Class Methods
# File lib/set.rb, line 71 def self.[](*ary) new(ary) end
Creates a new set containing the given objects.
# File lib/set.rb, line 80
def initialize(enum = nil, &block) # :yields: o
@hash ||= Hash.new
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.
Public Instance Methods
# File lib/set.rb, line 405
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 lib/set.rb, line 398 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 lib/set.rb, line 423
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 lib/set.rb, line 415
def ^(enum)
n = Set.new(enum)
each { |o| if n.include?(o) then n.delete(o) else n.add(o) end }
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 lib/set.rb, line 289 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 lib/set.rb, line 297
def add?(o)
if include?(o)
nil
else
add(o)
end
end Adds the given object to the set and returns self. If the object is already in the set, returns nil.
# File lib/set.rb, line 457
def classify # :yields: o
block_given? or return enum_for(__method__)
h = {}
each { |i|
x = yield(i)
(h[x] ||= 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 lib/set.rb, line 142 def clear @hash.clear self end
Removes all elements and returns self.
# File lib/set.rb, line 343
def collect!
block_given? or return enum_for(__method__)
set = self.class.new
each { |o| set << yield(o) }
replace(set)
end Replaces the elements with ones returned by collect().
# File lib/set.rb, line 307 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 lib/set.rb, line 314
def delete?(o)
if include?(o)
delete(o)
else
nil
end
end Deletes the given object from the set and returns self. If the object is not in the set, returns nil.
# File lib/set.rb, line 324
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 lib/set.rb, line 274 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 lib/set.rb, line 486
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 lib/set.rb, line 281 def each(&block) block or return enum_for(__method__) @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 lib/set.rb, line 137 def empty? @hash.empty? end
Returns true if the set contains no elements.
# File lib/set.rb, line 196 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 lib/set.rb, line 202
def flatten!
if detect { |e| e.is_a?(Set) }
replace(flatten())
else
nil
end
end Equivalent to #flatten, but replaces the receiver with the result in place. Returns nil if no modifications were made.
# File lib/set.rb, line 211 def include?(o) @hash.include?(o) end
Returns true if the set contains the given object.
# File lib/set.rb, line 110 def initialize_clone(orig) super @hash = orig.instance_variable_get(:@hash).clone end
Clone internal hash.
# File lib/set.rb, line 104 def initialize_dup(orig) super @hash = orig.instance_variable_get(:@hash).dup end
Dup internal hash.
# File lib/set.rb, line 520
def inspect
ids = (Thread.current[InspectKey] ||= [])
if ids.include?(object_id)
return sprintf('#<%s: {...}>', self.class.name)
end
begin
ids << object_id
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 lib/set.rb, line 256
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 lib/set.rb, line 334
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 lib/set.rb, line 371
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 lib/set.rb, line 241
def proper_subset?(set)
set.is_a?(Set) or raise ArgumentError, "value must be a set"
return false if set.size <= size
all? { |o| set.include?(o) }
end Returns true if the set is a proper subset of the given set.
# File lib/set.rb, line 225
def proper_superset?(set)
set.is_a?(Set) or raise ArgumentError, "value must be a set"
return false if size <= set.size
set.all? { |o| include?(o) }
end Returns true if the set is a proper superset of the given set.
# File lib/set.rb, line 353 def reject!(&block) block or return enum_for(__method__) n = size delete_if(&block) size == n ? nil : self end
Equivalent to #delete_if, but returns nil if no changes were made.
# File lib/set.rb, line 149
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 Replaces the contents of the set with the contents of the given enumerable object and returns self.
# File lib/set.rb, line 362 def select!(&block) block or return enum_for(__method__) n = size keep_if(&block) size == n ? nil : self end
Equivalent to #keep_if, but returns nil if no changes were made.
# File lib/set.rb, line 131 def size @hash.size end
Returns the number of elements.
# File lib/set.rb, line 233
def subset?(set)
set.is_a?(Set) or raise ArgumentError, "value must be a set"
return false if set.size < size
all? { |o| set.include?(o) }
end Returns true if the set is a subset of the given set.
# File lib/set.rb, line 383
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 lib/set.rb, line 217
def superset?(set)
set.is_a?(Set) or raise ArgumentError, "value must be a set"
return false if size < set.size
set.all? { |o| include?(o) }
end Returns true if the set is a superset of the given set.
# File lib/set.rb, line 161 def to_a @hash.keys end
Converts the set to an array. The order of elements is uncertain.
# File lib/set.rb, line 170 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 lib/set.rb, line 390 def |(enum) dup.merge(enum) end
Returns a new set built by merging the set and the elements of the given enumerable object.
Ruby Core © 1993–2017 Yukihiro Matsumoto
Licensed under the Ruby License.
Ruby Standard Library © contributors
Licensed under their own licenses.