Set

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:

Equality of elements is determined according to Object#== 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.

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

Class Method Summary

.new(other : Indexable(T))
Optimized version of .new used when other is also an Indexable
.new(enumerable : Enumerable(T))
Creates a new set from the elements in enumerable.
.new(pull : JSON::PullParser)
.new(initial_capacity = nil)
Creates a new, empty Set.

Instance Method Summary

#&(other : Set)
Intersection: returns a new set containing elements common to both sets.
#-(other : Set)
Difference: returns a new set containing elements in this set that are not present in the other.
#-(other : Enumerable)
Difference: returns a new set containing elements in this set that are not present in the other enumerable.
#<<(object : T)
Alias for #add
#==(other : Set)
Returns true if both sets have the same elements.
#^(other : Set(U)) forall U
Symmetric Difference: returns a new set (self - other) | (other - self).
#^(other : Enumerable(U)) forall U
Symmetric Difference: returns a new set (self - other) | (other - self).
#add(object : T)
Adds object to the set and returns self.
#clear
Removes all elements in the set, and returns self.
#clone
Returns a new Set with all of the elements cloned.
#concat(elems)
Adds #each element of elems to the set and returns self.
#delete(object)
Removes the object from the set and returns self.
#dup
Returns a new Set with all of the same elements.
#each
Returns an iterator for each element of the set.
#each(&block)
Yields each element of the set, and returns self.
#empty?
Returns true if the set is empty.
#hash
#includes?(object)
Returns true if object exists in the set.
#inspect(io)
Alias of #to_s.
#intersects?(other : Set)
Returns true if the set and the given set have at least one element in common.
#pretty_print(pp) : Nil
#proper_subset?(other : Set)
Returns true if the set is a proper subset of the other set.
#proper_superset?(other : Set)
Returns true if the set is a superset of the other set.
#size
Returns the number of elements in the set.
#subset?(other : Set)
Returns true if the set is a subset of the other set.
#subtract(other : Enumerable)
Returns self after removing from it those elements that are present in the given enumerable.
#superset?(other : Set)
Returns true if the set is a superset of the other set.
#to_a
Returns the elements as an Array-
#to_json(json : JSON::Builder)
#to_s(io)
Writes a string representation of the set to io.
#to_yaml(yaml : YAML::Builder)
#|(other : Set(U)) forall U
Union: returns a new set containing all unique elements from both sets.

Instance methods inherited from module `Iterable(T)`

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Instance methods inherited from module `Enumerable(T)`

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Instance methods inherited from struct `Struct`

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Instance methods inherited from struct `Value`

Instance methods inherited from class `Object`

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Class methods inherited from class `Object`

Class Method Detail

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

Optimized version of .new used when other is also an Indexable

def self.new(enumerable : Enumerable(T))Source

Creates a new set from the elements in enumerable.

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

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

def self.new(initial_capacity = nil)Source

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.

Instance Method Detail

def &(other : Set)Source

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'}

def -(other : Set)Source

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'}

def -(other : Enumerable)Source

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'}

def <<(object : T)Source

Alias for #add

def ==(other : Set)Source

Returns true if both sets have the same elements.

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

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

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'}

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

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'}

def add(object : T)Source

Adds object to the set and returns self.

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

def clearSource

Removes all elements in the set, and returns self.

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

def cloneSource

Returns a new Set with all of the elements cloned.

def concat(elems)Source

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.

def delete(object)Source

Removes the object from the set and returns self.

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

def dupSource

Returns a new Set with all of the same elements.

def eachSource

Returns an iterator for each element of the set.

def each(&block)Source

Yields each element of the set, and returns self.

def empty?Source

Returns true if the set is empty.

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

def hashSource

def includes?(object)Source

Returns true if object exists in the set.

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

def inspect(io)Source

Alias of #to_s.

def intersects?(other : Set)Source

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

def pretty_print(pp) : Nil Source

def proper_subset?(other : Set)Source

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

def proper_superset?(other : Set)Source

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

def sizeSource

Returns the number of elements in the set.

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

def subset?(other : Set)Source

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

def subtract(other : Enumerable)Source

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}

def superset?(other : Set)Source