Elixir v1.7.4 MapSet View Source
Functions that work on sets.
MapSet is the “go to” set data structure in Elixir. A set can be constructed
using MapSet.new/0:
iex> MapSet.new()
#MapSet<[]>A set can contain any kind of elements, and elements in a set don’t have to be of the same type. By definition, sets can’t contain duplicate elements: when inserting an element in a set where it’s already present, the insertion is simply a no-op.
iex> map_set = MapSet.new()
iex> MapSet.put(map_set, "foo")
#MapSet<["foo"]>
iex> map_set |> MapSet.put("foo") |> MapSet.put("foo")
#MapSet<["foo"]>A MapSet is represented internally using the %MapSet{} struct. This struct
can be used whenever there’s a need to pattern match on something being a MapSet:
iex> match?(%MapSet{}, MapSet.new())
trueNote that, however, the struct fields are private and must not be accessed directly; use the functions in this module to perform operations on sets.
MapSets can also be constructed starting from other collection-type data
structures: for example, see MapSet.new/1 or Enum.into/2.
Link to this section Summary
Functions
Deletes value from map_set
Returns a set that is map_set1 without the members of map_set2
Checks if map_set1 and map_set2 have no members in common
Checks if two sets are equal
Returns a set containing only members that map_set1 and map_set2 have in common
Checks if map_set contains value
Returns a new set
Creates a set from an enumerable
Creates a set from an enumerable via the transformation function
Inserts value into map_set if map_set doesn’t already contain it
Returns the number of elements in map_set
Checks if map_set1’s members are all contained in map_set2
Converts map_set to a list
Returns a set containing all members of map_set1 and map_set2
Link to this section Types
Link to this section Functions
Deletes value from map_set.
Returns a new set which is a copy of map_set but without value.
Examples
iex> map_set = MapSet.new([1, 2, 3])
iex> MapSet.delete(map_set, 4)
#MapSet<[1, 2, 3]>
iex> MapSet.delete(map_set, 2)
#MapSet<[1, 3]>Returns a set that is map_set1 without the members of map_set2.
Examples
iex> MapSet.difference(MapSet.new([1, 2]), MapSet.new([2, 3, 4]))
#MapSet<[1]>Checks if map_set1 and map_set2 have no members in common.
Examples
iex> MapSet.disjoint?(MapSet.new([1, 2]), MapSet.new([3, 4]))
true
iex> MapSet.disjoint?(MapSet.new([1, 2]), MapSet.new([2, 3]))
falseChecks if two sets are equal.
The comparison between elements must be done using ===/2.
Examples
iex> MapSet.equal?(MapSet.new([1, 2]), MapSet.new([2, 1, 1]))
true
iex> MapSet.equal?(MapSet.new([1, 2]), MapSet.new([3, 4]))
falseReturns a set containing only members that map_set1 and map_set2 have in common.
Examples
iex> MapSet.intersection(MapSet.new([1, 2]), MapSet.new([2, 3, 4]))
#MapSet<[2]>
iex> MapSet.intersection(MapSet.new([1, 2]), MapSet.new([3, 4]))
#MapSet<[]>Checks if map_set contains value.
Examples
iex> MapSet.member?(MapSet.new([1, 2, 3]), 2)
true
iex> MapSet.member?(MapSet.new([1, 2, 3]), 4)
falseCreates a set from an enumerable.
Examples
iex> MapSet.new([:b, :a, 3])
#MapSet<[3, :a, :b]>
iex> MapSet.new([3, 3, 3, 2, 2, 1])
#MapSet<[1, 2, 3]>Creates a set from an enumerable via the transformation function.
Examples
iex> MapSet.new([1, 2, 1], fn x -> 2 * x end)
#MapSet<[2, 4]>Inserts value into map_set if map_set doesn’t already contain it.
Examples
iex> MapSet.put(MapSet.new([1, 2, 3]), 3)
#MapSet<[1, 2, 3]>
iex> MapSet.put(MapSet.new([1, 2, 3]), 4)
#MapSet<[1, 2, 3, 4]>Checks if map_set1’s members are all contained in map_set2.
This function checks if map_set1 is a subset of map_set2.
Examples
iex> MapSet.subset?(MapSet.new([1, 2]), MapSet.new([1, 2, 3]))
true
iex> MapSet.subset?(MapSet.new([1, 2, 3]), MapSet.new([1, 2]))
falseReturns a set containing all members of map_set1 and map_set2.
Examples
iex> MapSet.union(MapSet.new([1, 2]), MapSet.new([2, 3, 4]))
#MapSet<[1, 2, 3, 4]>