View Source MapSet (Elixir v1.14.0)
Functions that work on sets.
A set is a data structure that can contain unique elements of any kind,
without any particular order. MapSet is the "go to" set data structure in Elixir.
A set can be constructed using MapSet.new/0:
iex> MapSet.new()
MapSet.new([])Elements in a set don't have to be of the same type and they can be
populated from an enumerable using MapSet.new/1:
iex> MapSet.new([1, :two, {"three"}])
MapSet.new([1, :two, {"three"}])Elements can be inserted using MapSet.put/2:
iex> MapSet.new([2]) |> MapSet.put(4) |> MapSet.put(0)
MapSet.new([0, 2, 4])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.new(["foo"])
iex> map_set |> MapSet.put("foo") |> MapSet.put("foo")
MapSet.new(["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.
MapSet is built on top of Map, this means that they share many properties,
including logarithmic time complexity. See the documentation for Map for more
information on its execution time complexity.
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.
Filters the set by returning only the elements from set for which invoking
fun returns a truthy value.
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 a set by excluding the elements from set for which invoking fun
returns a truthy value.
Returns the number of elements in map_set.
Checks if map_set1's members are all contained in map_set2.
Returns a set with elements that are present in only one but not both sets.
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.new([1, 2, 3])
iex> MapSet.delete(map_set, 2)
MapSet.new([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.new([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 is done using ===/2,
which a set with 1 is not equivalent to a set with
1.0.
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]))
false
iex> MapSet.equal?(MapSet.new([1]), MapSet.new([1.0]))
false@spec filter(t(a), (a -> as_boolean(term()))) :: t(a) when a: value()
Filters the set by returning only the elements from set for which invoking
fun returns a truthy value.
Also see reject/2 which discards all elements where the function returns
a truthy value.
Note: if you find yourself doing multiple calls to
MapSet.filter/2andMapSet.reject/2in a pipeline, it is likely more efficient to useEnum.map/2andEnum.filter/2instead and convert to a map at the end usingMap.new/1.
Examples
iex> MapSet.filter(MapSet.new(1..5), fn x -> x > 3 end)
MapSet.new([4, 5])
iex> MapSet.filter(MapSet.new(["a", :b, "c"]), &is_atom/1)
MapSet.new([:b])Returns 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.new([2])
iex> MapSet.intersection(MapSet.new([1, 2]), MapSet.new([3, 4]))
MapSet.new([])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)
false@spec new() :: t()
Returns a new set.
Examples
iex> MapSet.new()
MapSet.new([])@spec new(Enumerable.t()) :: t()
Creates a set from an enumerable.
Examples
iex> MapSet.new([:b, :a, 3])
MapSet.new([3, :a, :b])
iex> MapSet.new([3, 3, 3, 2, 2, 1])
MapSet.new([1, 2, 3])@spec new(Enumerable.t(), (term() -> val)) :: t(val) when val: value()
Creates a set from an enumerable via the transformation function.
Examples
iex> MapSet.new([1, 2, 1], fn x -> 2 * x end)
MapSet.new([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.new([1, 2, 3])
iex> MapSet.put(MapSet.new([1, 2, 3]), 4)
MapSet.new([1, 2, 3, 4])@spec reject(t(a), (a -> as_boolean(term()))) :: t(a) when a: value()
Returns a set by excluding the elements from set for which invoking fun
returns a truthy value.
See also filter/2.
Examples
iex> MapSet.reject(MapSet.new(1..5), fn x -> rem(x, 2) != 0 end)
MapSet.new([2, 4])
iex> MapSet.reject(MapSet.new(["a", :b, "c"]), &is_atom/1)
MapSet.new(["a", "c"])@spec size(t()) :: non_neg_integer()
Returns the number of elements in map_set.
Examples
iex> MapSet.size(MapSet.new([1, 2, 3]))
3Checks 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 with elements that are present in only one but not both sets.
Examples
iex> MapSet.symmetric_difference(MapSet.new([1, 2, 3]), MapSet.new([2, 3, 4]))
MapSet.new([1, 4])Converts map_set to a list.
Examples
iex> MapSet.to_list(MapSet.new([1, 2, 3]))
[1, 2, 3]Returns 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.new([1, 2, 3, 4])