# ordsets

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Module

ordsets

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Module Summary

Functions for manipulating sets as ordered lists.

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Description

Sets are collections of elements with no duplicate elements. An ordset is a representation of a set, where an ordered list is used to store the elements of the set. An ordered list is more efficient than an unordered list. Elements are ordered according to the Erlang term order.

This module provides the same interface as the sets(3) module but with a defined representation. One difference is that while sets considers two elements as different if they do not match (=:=), this module considers two elements as different if and only if they do not compare equal (==).

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Data Types

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ordset(T) = [T]

As returned by new/0.

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Exports

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add_element(Element, Ordset1) -> Ordset2

### Types

Element = E
Ordset1 = ordset(T)
Ordset2 = ordset(T | E)

Returns a new ordered set formed from Ordset1 with Element inserted.

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del_element(Element, Ordset1) -> Ordset2

### Types

Element = term()
Ordset1 = Ordset2 = ordset(T)

Returns Ordset1, but with Element removed.

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filter(Pred, Ordset1) -> Ordset2

### Types

Pred = fun((Element :: T) -> boolean())
Ordset1 = Ordset2 = ordset(T)

Filters elements in Ordset1 with boolean function Pred.

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fold(Function, Acc0, Ordset) -> Acc1

### Types

Function =
fun((Element :: T, AccIn :: term()) -> AccOut :: term())
Ordset = ordset(T)
Acc0 = Acc1 = term()

Folds Function over every element in Ordset and returns the final value of the accumulator.

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from_list(List) -> Ordset

### Types

List = [T]
Ordset = ordset(T)

Returns an ordered set of the elements in List.

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intersection(OrdsetList) -> Ordset

### Types

OrdsetList = [ordset(term()), ...]
Ordset = ordset(term())

Returns the intersection of the non-empty list of sets.

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intersection(Ordset1, Ordset2) -> Ordset3

### Types

Ordset1 = Ordset2 = Ordset3 = ordset(term())

Returns the intersection of Ordset1 and Ordset2.

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is_disjoint(Ordset1, Ordset2) -> boolean()

### Types

Ordset1 = Ordset2 = ordset(term())

Returns true if Ordset1 and Ordset2 are disjoint (have no elements in common), otherwise false.

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is_element(Element, Ordset) -> boolean()

### Types

Element = term()
Ordset = ordset(term())

Returns true if Element is an element of Ordset, otherwise false.

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is_empty(Ordset) -> boolean()
OTP 21.0

### Types

Ordset = ordset(term())

Returns true if Ordset is an empty set, otherwise false.

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is_set(Ordset) -> boolean()

### Types

Ordset = term()

Returns true if Ordset is an ordered set of elements, otherwise false. This function will return true for any ordered list, even when not constructed by the functions in this module.

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is_subset(Ordset1, Ordset2) -> boolean()

### Types

Ordset1 = Ordset2 = ordset(term())

Returns true when every element of Ordset1 is also a member of Ordset2, otherwise false.

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new() -> []

Returns a new empty ordered set.

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size(Ordset) -> integer() >= 0

### Types

Ordset = ordset(term())

Returns the number of elements in Ordset.

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subtract(Ordset1, Ordset2) -> Ordset3

### Types

Ordset1 = Ordset2 = Ordset3 = ordset(term())

Returns only the elements of Ordset1 that are not also elements of Ordset2.

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to_list(Ordset) -> List

### Types

Ordset = ordset(T)
List = [T]

Returns the elements of Ordset as a list.

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union(OrdsetList) -> Ordset

### Types

OrdsetList = [ordset(T)]
Ordset = ordset(T)

Returns the merged (union) set of the list of sets.

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union(Ordset1, Ordset2) -> Ordset3

### Types

Ordset1 = ordset(T1)
Ordset2 = ordset(T2)
Ordset3 = ordset(T1 | T2)

Returns the merged (union) set of Ordset1 and Ordset2.

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See Also

gb_sets(3), sets(3)