struct

# Set

A set data type.

O(1) average-case amortized add, remove, and membership check.

from collections import Setvar set = Set[Int](1, 2, 3)print(len(set))  # 3set.add(4)for element in set:    print(element[])set -= Set[Int](3, 4, 5)print(set == Set[Int](1, 2))  # Trueprint(set | Set[Int](0, 1) == Set[Int](0, 1, 2))  # Truevar element = set.pop()print(len(set))  # 1

## Parameters​

• T (KeyElement): The element type of the set. Must implement KeyElement.

## Implemented traits​

AnyType, Boolable, EqualityComparable, Hashable, Sized

## Methods​

### __init__​

__init__(inout self: Self, /, *ts: T)

Construct a set from initial elements.

Args:

• *ts (T): Variadic of elements to add to the set.

__init__(inout self: Self, /, elements: Self)

Explicitly copy another Set instance.

Args:

• elements (Self): An existing set to copy.

__init__(inout self: Self, /, elements: List[T])

Construct a set from a List of elements.

Args:

• elements (List[T]): A vector of elements to add to the set.

### __moveinit__​

__moveinit__(inout self: Self, /, owned other: Self)

Move constructor.

Args:

• other (Self): The existing Set instance to move from.

### __bool__​

__bool__(self: Self) -> Bool

Whether the set is non-empty or not.

Returns:

True if the set is non-empty, False if it is empty.

### __eq__​

__eq__(self: Self, other: Self) -> Bool

Set equality.

Args:

• other (Self): Another Set instance to check equality against.

Returns:

True if the sets contain the same elements and False otherwise.

### __ne__​

__ne__(self: Self, other: Self) -> Bool

Set inequality.

Args:

• other (Self): Another Set instance to check equality against.

Returns:

True if the sets are different and False otherwise.

### __contains__​

__contains__(self: Self, t: T) -> Bool

Whether or not the set contains an element.

Args:

• t (T): The element to check membership in the set.

Returns:

Whether or not the set contains the element.

### __sub__​

__sub__(self: Self, other: Self) -> Self

Set subtraction.

Args:

• other (Self): Another Set instance to subtract from this one.

Returns:

A new set containing elements of this set, but not containing any elements which were in the other set.

### __and__​

__and__(self: Self, other: Self) -> Self

The set intersection operator.

Args:

• other (Self): Another Set instance to intersect with this one.

Returns:

A new set containing only the elements which appear in both this set and the other set.

### __or__​

__or__(self: Self, other: Self) -> Self

The set union operator.

Args:

• other (Self): Another Set instance to union with this one.

Returns:

A new set containing any elements which appear in either this set or the other set.

### __isub__​

__isub__(inout self: Self, other: Self)

In-place set subtraction.

Updates the set to remove any elements from the other set.

Args:

• other (Self): Another Set instance to subtract from this one.

### __iand__​

__iand__(inout self: Self, other: Self)

In-place set intersection.

Updates the set to contain only the elements which are already in the set and are also contained in the other set.

Args:

• other (Self): Another Set instance to intersect with this one.

### __ior__​

__ior__(inout self: Self, other: Self)

In-place set union.

Updates the set to contain all elements in the other set as well as keeping all elements it already contained.

Args:

• other (Self): Another Set instance to union with this one.

### __len__​

__len__(self: Self) -> Int

The size of the set.

Returns:

The number of elements in the set.

### __hash__​

__hash__(self: Self) -> Int

A hash value of the elements in the set.

The hash value is order independent, so s1 == s2 -> hash(s1) == hash(s2).

Returns:

A hash value of the set suitable for non-cryptographic purposes.

### __iter__​

__iter__[mutability: i1, self_life: lifetime<*(0,0)>](self: !lit.ref<_stdlib::_collections::_set::_Set<:trait<_stdlib::_collections::_dict::_KeyElement> T>, mut=mutability, self_life>) -> _DictKeyIter[T, None, $0,$1, true]

Iterate over elements of the set, returning immutable references.

Returns:

An iterator of immutable references to the set elements.

### add​

add(inout self: Self, t: T)

Add an element to the set.

Args:

• t (T): The element to add to the set.

### remove​

remove(inout self: Self, t: T)

Remove an element from the set.

Args:

• t (T): The element to remove from the set.

Raises:

If the element isn't in the set to remove.

### pop​

pop(inout self: Self) -> T

Remove any one item from the set, and return it.

As an implementation detail this will remove the first item according to insertion order. This is practically useful for breadth-first search implementations.

Returns:

The element which was removed from the set.

Raises:

If the set is empty.

### union​

union(self: Self, other: Self) -> Self

Set union.

Args:

• other (Self): Another Set instance to union with this one.

Returns:

A new set containing any elements which appear in either this set or the other set.

### intersection​

intersection(self: Self, other: Self) -> Self

Set intersection.

Args:

• other (Self): Another Set instance to intersect with this one.

Returns:

A new set containing only the elements which appear in both this set and the other set.

### difference​

difference(self: Self, other: Self) -> Self

Set difference.

Args:

• other (Self): Another Set instance to find the difference with this one.

Returns:

A new set containing elements that are in this set but not in the other set.

### update​

update(inout self: Self, other: Self)

In-place set update.

Updates the set to contain all elements in the other set as well as keeping all elements it already contained.

Args:

• other (Self): Another Set instance to union with this one.

### difference_update​

difference_update(inout self: Self, other: Self)

In-place set difference update.

Updates the set by removing all elements found in the other set, effectively keeping only elements that are unique to this set.

Args:

• other (Self): Another Set instance to compare with this one.

### intersection_update​

intersection_update(inout self: Self, other: Self)

In-place set intersection update.

Updates the set by retaining only elements found in both this set and the other set, removing all other elements. The result is the intersection of this set with other.

Args:

• other (Self): Another Set instance to intersect with this one.

### remove_all​

remove_all(inout self: Self, other: Self)

In-place set subtraction.

Updates the set to remove any elements from the other set.

Args:

• other (Self): Another Set instance to subtract from this one.