Class Set
In: lib/set.rb
Parent: Object

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.

Several methods accept any Enumerable object (implementing each) for greater flexibility: new, replace, merge, subtract, |, &, -, ^.

The equality of each couple of elements is determined according to Object#eql? and Object#hash, since Set uses Hash as storage.

Finally, if you are using class Set, you can also use Enumerable#to_set for convenience.

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: {6, 1, 2, "foo"}>
  s1.subset? s2                         # -> false
  s2.subset? s1                         # -> true

Contact

  - Akinori MUSHA <knu@iDaemons.org> (current maintainer)

Methods

&   +   -   <<   ==   []   ^   add   add?   classify   clear   collect!   delete   delete?   delete_if   difference   divide   each   empty?   flatten   flatten!   flatten_merge   include?   initialize_copy   inspect   intersection   length   map!   member?   merge   new   proper_subset?   proper_superset?   reject!   replace   size   subset?   subtract   superset?   to_a   union   |  

Included Modules

Enumerable

Public Class methods

Creates a new set containing the given objects.

[Source]

    # File lib/set.rb, line 59
59:   def self.[](*ary)
60:     new(ary)
61:   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.

[Source]

    # File lib/set.rb, line 68
68:   def initialize(enum = nil, &block) # :yields: o
69:     @hash ||= Hash.new
70: 
71:     enum.nil? and return
72: 
73:     if block
74:       enum.each { |o| add(block[o]) }
75:     else
76:       merge(enum)
77:     end
78:   end

Public Instance methods

Returns a new set containing elements common to the set and the given enumerable object.

[Source]

     # File lib/set.rb, line 297
297:   def &(enum)
298:     enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
299:     n = self.class.new
300:     enum.each { |o| n.add(o) if include?(o) }
301:     n
302:   end
+(enum)

Alias for #|

Returns a new set built by duplicating the set, removing every element that appears in the given enumerable object.

[Source]

     # File lib/set.rb, line 289
289:   def -(enum)
290:     enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
291:     dup.subtract(enum)
292:   end
<<(o)

Alias for add

Returns true if two sets are equal. The equality of each couple of elements is defined according to Object#eql?.

[Source]

     # File lib/set.rb, line 317
317:   def ==(set)
318:     equal?(set) and return true
319: 
320:     set.is_a?(Set) && size == set.size or return false
321: 
322:     hash = @hash.dup
323:     set.all? { |o| hash.include?(o) }
324:   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)).

[Source]

     # File lib/set.rb, line 308
308:   def ^(enum)
309:     enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
310:     n = Set.new(enum)
311:     each { |o| if n.include?(o) then n.delete(o) else n.add(o) end }
312:     n
313:   end

Adds the given object to the set and returns self. Use merge to add several elements at once.

[Source]

     # File lib/set.rb, line 201
201:   def add(o)
202:     @hash[o] = true
203:     self
204:   end

Adds the given object to the set and returns self. If the object is already in the set, returns nil.

[Source]

     # File lib/set.rb, line 209
209:   def add?(o)
210:     if include?(o)
211:       nil
212:     else
213:       add(o)
214:     end
215:   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"}>}

[Source]

     # File lib/set.rb, line 348
348:   def classify # :yields: o
349:     h = {}
350: 
351:     each { |i|
352:       x = yield(i)
353:       (h[x] ||= self.class.new).add(i)
354:     }
355: 
356:     h
357:   end

Removes all elements and returns self.

[Source]

     # File lib/set.rb, line 97
 97:   def clear
 98:     @hash.clear
 99:     self
100:   end

Do collect() destructively.

[Source]

     # File lib/set.rb, line 242
242:   def collect!
243:     set = self.class.new
244:     each { |o| set << yield(o) }
245:     replace(set)
246:   end

Deletes the given object from the set and returns self. Use subtract to delete several items at once.

[Source]

     # File lib/set.rb, line 219
219:   def delete(o)
220:     @hash.delete(o)
221:     self
222:   end

Deletes the given object from the set and returns self. If the object is not in the set, returns nil.

[Source]

     # File lib/set.rb, line 226
226:   def delete?(o)
227:     if include?(o)
228:       delete(o)
229:     else
230:       nil
231:     end
232:   end

Deletes every element of the set for which block evaluates to true, and returns self.

[Source]

     # File lib/set.rb, line 236
236:   def delete_if
237:     to_a.each { |o| @hash.delete(o) if yield(o) }
238:     self
239:   end
difference(enum)

Alias for #-

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}>}>

[Source]

     # File lib/set.rb, line 375
375:   def divide(&func)
376:     if func.arity == 2
377:       require 'tsort'
378: 
379:       class << dig = {}         # :nodoc:
380:         include TSort
381: 
382:         alias tsort_each_node each_key
383:         def tsort_each_child(node, &block)
384:           fetch(node).each(&block)
385:         end
386:       end
387: 
388:       each { |u|
389:         dig[u] = a = []
390:         each{ |v| func.call(u, v) and a << v }
391:       }
392: 
393:       set = Set.new()
394:       dig.each_strongly_connected_component { |css|
395:         set.add(self.class.new(css))
396:       }
397:       set
398:     else
399:       Set.new(classify(&func).values)
400:     end
401:   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.

[Source]

     # File lib/set.rb, line 193
193:   def each
194:     block_given? or return enum_for(__method__)
195:     @hash.each_key { |o| yield(o) }
196:     self
197:   end

Returns true if the set contains no elements.

[Source]

    # File lib/set.rb, line 92
92:   def empty?
93:     @hash.empty?
94:   end

Returns a new set that is a copy of the set, flattening each containing set recursively.

[Source]

     # File lib/set.rb, line 142
142:   def flatten
143:     self.class.new.flatten_merge(self)
144:   end

Equivalent to Set#flatten, but replaces the receiver with the result in place. Returns nil if no modifications were made.

[Source]

     # File lib/set.rb, line 148
148:   def flatten!
149:     if detect { |e| e.is_a?(Set) }
150:       replace(flatten())
151:     else
152:       nil
153:     end
154:   end

Returns true if the set contains the given object.

[Source]

     # File lib/set.rb, line 157
157:   def include?(o)
158:     @hash.include?(o)
159:   end

Copy internal hash.

[Source]

    # File lib/set.rb, line 81
81:   def initialize_copy(orig)
82:     @hash = orig.instance_eval{@hash}.dup
83:   end

Returns a string containing a human-readable representation of the set. ("#<Set: {element1, element2, …}>")

[Source]

     # File lib/set.rb, line 407
407:   def inspect
408:     ids = (Thread.current[InspectKey] ||= [])
409: 
410:     if ids.include?(object_id)
411:       return sprintf('#<%s: {...}>', self.class.name)
412:     end
413: 
414:     begin
415:       ids << object_id
416:       return sprintf('#<%s: {%s}>', self.class, to_a.inspect[1..-2])
417:     ensure
418:       ids.pop
419:     end
420:   end
intersection(enum)

Alias for #&

length()

Alias for size

map!()

Alias for collect!

member?(o)

Alias for include?

Merges the elements of the given enumerable object to the set and returns self.

[Source]

     # File lib/set.rb, line 259
259:   def merge(enum)
260:     if enum.is_a?(Set)
261:       @hash.update(enum.instance_eval { @hash })
262:     else
263:       enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
264:       enum.each { |o| add(o) }
265:     end
266: 
267:     self
268:   end

Returns true if the set is a proper subset of the given set.

[Source]

     # File lib/set.rb, line 184
184:   def proper_subset?(set)
185:     set.is_a?(Set) or raise ArgumentError, "value must be a set"
186:     return false if set.size <= size
187:     all? { |o| set.include?(o) }
188:   end

Returns true if the set is a proper superset of the given set.

[Source]

     # File lib/set.rb, line 170
170:   def proper_superset?(set)
171:     set.is_a?(Set) or raise ArgumentError, "value must be a set"
172:     return false if size <= set.size
173:     set.all? { |o| include?(o) }
174:   end

Equivalent to Set#delete_if, but returns nil if no changes were made.

[Source]

     # File lib/set.rb, line 251
251:   def reject!
252:     n = size
253:     delete_if { |o| yield(o) }
254:     size == n ? nil : self
255:   end

Replaces the contents of the set with the contents of the given enumerable object and returns self.

[Source]

     # File lib/set.rb, line 104
104:   def replace(enum)
105:     if enum.class == self.class
106:       @hash.replace(enum.instance_eval { @hash })
107:     else
108:       enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
109:       clear
110:       enum.each { |o| add(o) }
111:     end
112: 
113:     self
114:   end

Returns the number of elements.

[Source]

    # File lib/set.rb, line 86
86:   def size
87:     @hash.size
88:   end

Returns true if the set is a subset of the given set.

[Source]

     # File lib/set.rb, line 177
177:   def subset?(set)
178:     set.is_a?(Set) or raise ArgumentError, "value must be a set"
179:     return false if set.size < size
180:     all? { |o| set.include?(o) }
181:   end

Deletes every element that appears in the given enumerable object and returns self.

[Source]

     # File lib/set.rb, line 272
272:   def subtract(enum)
273:     enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
274:     enum.each { |o| delete(o) }
275:     self
276:   end

Returns true if the set is a superset of the given set.

[Source]

     # File lib/set.rb, line 163
163:   def superset?(set)
164:     set.is_a?(Set) or raise ArgumentError, "value must be a set"
165:     return false if size < set.size
166:     set.all? { |o| include?(o) }
167:   end

Converts the set to an array. The order of elements is uncertain.

[Source]

     # File lib/set.rb, line 117
117:   def to_a
118:     @hash.keys
119:   end
union(enum)

Alias for #|

Returns a new set built by merging the set and the elements of the given enumerable object.

[Source]

     # File lib/set.rb, line 280
280:   def |(enum)
281:     enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
282:     dup.merge(enum)
283:   end

Protected Instance methods

[Source]

     # File lib/set.rb, line 121
121:   def flatten_merge(set, seen = Set.new)
122:     set.each { |e|
123:       if e.is_a?(Set)
124:         if seen.include?(e_id = e.object_id)
125:           raise ArgumentError, "tried to flatten recursive Set"
126:         end
127: 
128:         seen.add(e_id)
129:         flatten_merge(e, seen)
130:         seen.delete(e_id)
131:       else
132:         add(e)
133:       end
134:     }
135: 
136:     self
137:   end

[Validate]