struct Set(T)

Overview

Set implements a collection of unordered values with no duplicates.

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:

Example

s1 = Set{1, 2}
s2 = [1, 2].to_set
s3 = Set.new [1, 2]
s1 == s2 # => true
s1 == s3 # => true
s1.add(2)
s1.concat([6, 8])
s1.subset? s2 # => false
s2.subset? s1 # => true

Included Modules

Defined in:

set.cr
json/to_json.cr
yaml/to_yaml.cr

Constructors

Instance Method Summary

Instance methods inherited from module Iterable(T)

chunk(reuse = false, &block : T -> U) forall U chunk, cycle(n)
cycle cycle, each each, each_cons(count : Int, reuse = false) each_cons, each_slice(count : Int, reuse = false) each_slice, each_with_index(offset = 0) each_with_index, each_with_object(obj) each_with_object

Instance methods inherited from module Enumerable(T)

all?(&block)
all? all?, any?(&block)
any? any?, chunks(&block : T -> U) forall U chunks, compact_map(&block) compact_map, count(&block)
count(item) count, cycle(n, &block)
cycle(&block) cycle, each(&block : T -> _) each, each_cons(count : Int, reuse = false, &block) each_cons, each_slice(count : Int, reuse = false, &block) each_slice, each_with_index(offset = 0, &block) each_with_index, each_with_object(obj, &block) each_with_object, find(if_none = nil, &block) find, first(count : Int)
first first, first? first?, flat_map(&block : T -> Array(U) | Iterator(U) | U) forall U flat_map, grep(pattern) grep, group_by(&block : T -> U) forall U group_by, in_groups_of(size : Int, filled_up_with : U = nil) forall U
in_groups_of(size : Int, filled_up_with : U = nil, reuse = false, &block) forall U in_groups_of, includes?(obj) includes?, index(&block)
index(obj) index, index_by(&block : T -> U) forall U index_by, join(separator, io)
join(separator = "")
join(separator, io, &block)
join(separator = "", &block) join, map(&block : T -> U) forall U map, map_with_index(&block : T, Int32 -> U) forall U map_with_index, max max, max? max?, max_by(&block : T -> U) forall U max_by, max_by?(&block : T -> U) forall U max_by?, max_of(&block : T -> U) forall U max_of, max_of?(&block : T -> U) forall U max_of?, min min, min? min?, min_by(&block : T -> U) forall U min_by, min_by?(&block : T -> U) forall U min_by?, min_of(&block : T -> U) forall U min_of, min_of?(&block : T -> U) forall U min_of?, minmax minmax, minmax? minmax?, minmax_by(&block : T -> U) forall U minmax_by, minmax_by?(&block : T -> U) forall U minmax_by?, minmax_of(&block : T -> U) forall U minmax_of, minmax_of?(&block : T -> U) forall U minmax_of?, none?(&block)
none? none?, one?(&block) one?, partition(&block) partition, product(&block)
product(initial : Number, &block)
product
product(initial : Number) product, reduce(&block)
reduce(memo, &block) reduce, reject(&block : T -> ) reject, select(&block : T -> ) select, size size, skip(count : Int) skip, skip_while(&block) skip_while, sum(initial)
sum
sum(initial, &block)
sum(&block) sum, take_while(&block) take_while, to_a to_a, to_h to_h, to_set to_set

Instance methods inherited from struct Struct

==(other : self) : Bool ==, hash : Int32 hash, inspect(io : IO) : Nil inspect, pretty_print(pp) : Nil pretty_print, to_s(io) to_s

Instance methods inherited from struct Value

==(other) ==, dup dup

Instance methods inherited from class Object

!=(other) !=, !~(other) !~, ==(other) ==, ===(other : JSON::Any)
===(other : YAML::Any)
===(other) ===, =~(other) =~, class class, dup dup, hash hash, inspect(io : IO)
inspect inspect, itself itself, not_nil! not_nil!, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, tap(&block) tap, to_json(io : IO)
to_json to_json, to_pretty_json(indent : String = " ")
to_pretty_json(io : IO, indent : String = " ") to_pretty_json, to_s
to_s(io : IO) to_s, to_yaml(io : IO)
to_yaml to_yaml, try(&block) try, unsafe_as(type : T.class) forall T unsafe_as

Constructor methods inherited from class Object

from_json(string_or_io, root : String) : self
from_json(string_or_io) : self from_json, from_yaml(string_or_io) : self from_yaml

Constructor Detail

def self.new(other : Indexable(T)) #

Optimized version of new used when other is also an Indexable


View source
def self.new(enumerable : Enumerable(T)) #

Creates a new set from the elements in enumerable.

a = [1, 3, 5]
s = Set.new a
s.empty? # => false

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def self.new(pull : JSON::PullParser) #

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def self.new(initial_capacity = nil) #

Creates a new, empty Set.

s = Set(Int32).new
s.empty? # => true

An initial capacity can be specified, and it will be set as the initial capacity of the internal Hash.


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Instance Method Detail

def &(other : Set) #

Intersection: returns a new set containing elements common to both sets.

Set{1, 1, 3, 5} & Set{1, 2, 3}               # => Set{1, 3}
Set{'a', 'b', 'b', 'z'} & Set{'a', 'b', 'c'} # => Set{'a', 'b'}

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def -(other : Set) #

Difference: returns a new set containing elements in this set that are not present in the other.

Set{1, 2, 3, 4, 5} - Set{2, 4}               # => Set{1, 3, 5}
Set{'a', 'b', 'b', 'z'} - Set{'a', 'b', 'c'} # => Set{'z'}

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def -(other : Enumerable) #

Difference: returns a new set containing elements in this set that are not present in the other enumerable.

Set{1, 2, 3, 4, 5} - [2, 4]               # => Set{1, 3, 5}
Set{'a', 'b', 'b', 'z'} - ['a', 'b', 'c'] # => Set{'z'}

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def <<(object : T) #

Alias for #add


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def ==(other : Set) #

Returns true if both sets have the same elements.

Set{1, 5} == Set{1, 5} # => true

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def ^(other : Set(U)) forall U #

Symmetric Difference: returns a new set (self - other) | (other - self). Equivalently, returns (self | other) - (self & other).

Set{1, 2, 3, 4, 5} ^ Set{2, 4, 6}            # => Set{1, 3, 5, 6}
Set{'a', 'b', 'b', 'z'} ^ Set{'a', 'b', 'c'} # => Set{'z', 'c'}

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def ^(other : Enumerable(U)) forall U #

Symmetric Difference: returns a new set (self - other) | (other - self). Equivalently, returns (self | other) - (self & other).

Set{1, 2, 3, 4, 5} ^ [2, 4, 6]            # => Set{1, 3, 5, 6}
Set{'a', 'b', 'b', 'z'} ^ ['a', 'b', 'c'] # => Set{'z', 'c'}

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def add(object : T) #

Adds object to the set and returns self.

s = Set{1, 5}
s.includes? 8 # => false
s << 8
s.includes? 8 # => true

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def clear #

Removes all elements in the set, and returns self.

s = Set{1, 5}
s.size # => 2
s.clear
s.size # => 0

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def clone #

Returns a new Set with all of the elements cloned.


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def concat(elems) #

Adds #each element of elems to the set and returns self.

s = Set{1, 5}
s.concat [5, 5, 8, 9]
s.size # => 4

See also: #| to merge two sets and return a new one.


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def delete(object) #

Removes the object from the set and returns self.

s = Set{1, 5}
s.includes? 5 # => true
s.delete 5
s.includes? 5 # => false

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def dup #

Returns a new Set with all of the same elements.


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def each #

Returns an iterator for each element of the set.


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def each(&block) #

Yields each element of the set, and returns self.


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def empty? #

Returns true if the set is empty.

s = Set(Int32).new
s.empty? # => true
s << 3
s.empty? # => false

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def hash #

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def includes?(object) #

Returns true if object exists in the set.

s = Set{1, 5}
s.includes? 5 # => true
s.includes? 9 # => false

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def inspect(io) #

Alias of #to_s.


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def intersects?(other : Set) #

Returns true if the set and the given set have at least one element in common.

Set{1, 2, 3}.intersects? Set{4, 5} # => false
Set{1, 2, 3}.intersects? Set{3, 4} # => true

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def pretty_print(pp) : Nil #

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def proper_subset?(other : Set) #

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

This set must have fewer elements than the other set, and all of elements in this set must be present in the other set.

Set{1, 5}.proper_subset? Set{1, 3, 5}    # => true
Set{1, 3, 5}.proper_subset? Set{1, 3, 5} # => false

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def proper_superset?(other : Set) #

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

The other must have the same or fewer elements than this set, and all of elements in the other set must be present in this set.

Set{1, 3, 5}.proper_superset? Set{1, 5}    # => true
Set{1, 3, 5}.proper_superset? Set{1, 3, 5} # => false

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def size #

Returns the number of elements in the set.

s = Set{1, 5}
s.size # => 2

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def subset?(other : Set) #

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

This set must have the same or fewer elements than the other set, and all of elements in this set must be present in the other set.

Set{1, 5}.subset? Set{1, 3, 5}    # => true
Set{1, 3, 5}.subset? Set{1, 3, 5} # => true

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def subtract(other : Enumerable) #

Returns self after removing from it those elements that are present in the given enumerable.

Set{'a', 'b', 'b', 'z'}.subtract Set{'a', 'b', 'c'} # => Set{'z'}
Set{1, 2, 3, 4, 5}.subtract [2, 4, 6]               # => Set{1, 3, 5}

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def superset?(other : Set) #

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

The other must have the same or fewer elements than this set, and all of elements in the other set must be present in this set.

Set{1, 3, 5}.superset? Set{1, 5}    # => true
Set{1, 3, 5}.superset? Set{1, 3, 5} # => true

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def to_a #

Returns the elements as an Array.

Set{1, 5}.to_a # => [1,5]

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def to_json(json : JSON::Builder) #

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def to_s(io) #

Writes a string representation of the set to io.


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def to_yaml(yaml : YAML::Builder) #

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def |(other : Set(U)) forall U #

Union: returns a new set containing all unique elements from both sets.

Set{1, 1, 3, 5} | Set{1, 2, 3}               # => Set{1, 3, 5, 2}
Set{'a', 'b', 'b', 'z'} | Set{'a', 'b', 'c'} # => Set{'a', 'b', 'z', 'c'}

See also: #concat to add elements from a set to self.


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