--experimental_enable_starlark_set.
The built-in mutable set type. Example set expressions:
x = set() # x is an empty set y = set([1, 2, 3]) # y is a set with 3 elements 3 in y # True 0 in y # False len(x) # 0 len(y) # 3
A set used in Boolean context is true if and only if it is non-empty.
s = set() "non-empty" if s else "empty" # "empty" t = set(["x", "y"]) "non-empty" if t else "empty" # "non-empty"
The elements of a set must be hashable; x may be an element of a set if and only if
x may be used as a key of a dict.
A set itself is not hashable; therefore, you cannot have a set with another set as an element.
You cannot access the elements of a set by index, but you can iterate over them, and you can
obtain the list of a set's elements in iteration order using the list() built-in
function. Just like for lists, it is an error to mutate a set while it is being iterated over. The
order of iteration matches insertion order:
s = set([3, 1, 3])
s.add(2)
# prints 3, 1, 2
for item in s:
print(item)
list(s) # [3, 1, 2]
A set s is equal to t if and only if t is a set containing
the same elements, possibly with a different iteration order. In particular, a set is
not equal to its list of elements.
Sets are not ordered; the <, <=, >, and
>= operations are not defined for sets, and a list of sets cannot be sorted - unlike
in Python.
The | operation on two sets returns the union of the two sets: a set containing the
elements found in either one or both of the original sets. The | operation has an
augmented assignment version; s |= t adds to s all the elements of
t.
set([1, 2]) | set([3, 2]) # set([1, 2, 3]) s = set([1, 2]) s |= set([2, 3, 4]) # s now equals set([1, 2, 3, 4])
The & operation on two sets returns the intersection of the two sets: a set
containing only the elements found in both of the original sets. The & operation
has an augmented assignment version; s &= t removes from s all the
elements not found in t.
set([1, 2]) & set([2, 3]) # set([2]) set([1, 2]) & set([3, 4]) # set() s = set([1, 2]) s &= set([0, 1]) # s now equals set([1])
The - operation on two sets returns the difference of the two sets: a set containing
the elements found in the left-hand side set but not the right-hand site set. The -
operation has an augmented assignment version; s -= t removes from s all
the elements found in t.
set([1, 2]) - set([2, 3]) # set([1]) set([1, 2]) - set([3, 4]) # set([1, 2]) s = set([1, 2]) s -= set([0, 1]) # s now equals set([2])
The ^ operation on two sets returns the symmetric difference of the two sets: a set
containing the elements found in exactly one of the two original sets, but not in both. The
^ operation has an augmented assignment version; s ^= t removes from
s any element of t found in s and adds to s any
element of t not found in s.
set([1, 2]) ^ set([2, 3]) # set([1, 3]) set([1, 2]) ^ set([3, 4]) # set([1, 2, 3, 4]) s = set([1, 2]) s ^= set([0, 1]) # s now equals set([2, 0])
Members
- add
- clear
- difference
- difference_update
- discard
- intersection
- intersection_update
- isdisjoint
- issubset
- issuperset
- pop
- remove
- symmetric_difference
- symmetric_difference_update
- union
- update
add
None set.add(element)Parameters
| Parameter | Description |
|---|---|
element
|
required Element to add. |
clear
None set.clear()difference
set set.difference(*others)Returns a new mutable set containing the difference of this set with others.
For example,
set([1, 2, 3]).intersection([1, 2], [2, 3]) == set([2])
Parameters
| Parameter | Description |
|---|---|
others
|
required Sets, sequences, or dicts. |
difference_update
None set.difference_update(*others)For example,
x = set([1, 2, 3, 4]) x.difference_update([2, 3], [3, 4]) # x is now set([1])
Parameters
| Parameter | Description |
|---|---|
others
|
required Sets, sequences, or dicts. |
discard
None set.discard(element)Parameters
| Parameter | Description |
|---|---|
element
|
required Element to discard. |
intersection
set set.intersection(*others)Returns a new mutable set containing the intersection of this set with others.
For example,
set([1, 2, 3]).intersection([1, 2], [2, 3]) == set([2])
Parameters
| Parameter | Description |
|---|---|
others
|
required Sets, sequences, or dicts. |
intersection_update
None set.intersection_update(*others)For example,
x = set([1, 2, 3, 4]) x.intersection_update([2, 3], [3, 4]) # x is now set([3])
Parameters
| Parameter | Description |
|---|---|
others
|
required Sets, sequences, or dicts. |
isdisjoint
bool set.isdisjoint(other)Returns true if this set has no elements in common with another.
For example,
set([1, 2]).isdisjoint([3, 4]) == True set().isdisjoint(set()) == True set([1, 2]).isdisjoint([2, 3]) == False
Parameters
| Parameter | Description |
|---|---|
other
|
required A set, sequence, or dict. |
issubset
bool set.issubset(other)Returns true of this set is a subset of another.
For example,
set([1, 2]).issubset([1, 2, 3]) == True set([1, 2]).issubset([1, 2]) == True set([1, 2]).issubset([2, 3]) == False
Parameters
| Parameter | Description |
|---|---|
other
|
required A set, sequence, or dict. |
issuperset
bool set.issuperset(other)Returns true of this set is a superset of another.
For example,
set([1, 2, 3]).issuperset([1, 2]) == True set([1, 2, 3]).issuperset([1, 2, 3]) == True set([1, 2, 3]).issuperset([2, 3, 4]) == False
Parameters
| Parameter | Description |
|---|---|
other
|
required A set, sequence, or dict. |
pop
unknown set.pop()Removes and returns the first element of the set. Fails if the set is empty.
remove
None set.remove(element)Parameters
| Parameter | Description |
|---|---|
element
|
required Element to remove. |
symmetric_difference
set set.symmetric_difference(other)Returns a new mutable set containing the symmetric difference of this set with another set, sequence, or dict.
For example,
set([1, 2, 3]).symmetric_difference([2, 3, 4]) == set([1, 4])
Parameters
| Parameter | Description |
|---|---|
other
|
required A set, sequence, or dict. |
symmetric_difference_update
None set.symmetric_difference_update(other)For example,
set([1, 2, 3]).symmetric_difference([2, 3, 4]) == set([1, 4])
Parameters
| Parameter | Description |
|---|---|
other
|
required A set, sequence, or dict. |
union
set set.union(*others)Returns a new mutable set containing the union of this set with others.
For example,
set([1, 2]).union([2, 3, 4], [4, 5]) == set([1, 2, 3, 4, 5])
Parameters
| Parameter | Description |
|---|---|
others
|
required Sets, sequences, or dicts. |
update
None set.update(*others)For example,
x = set([1, 2]) x.update([2, 3], [3, 4]) # x is now set([1, 2, 3, 4])
Parameters
| Parameter | Description |
|---|---|
others
|
required Sets, sequences, or dicts. |