ubelt.orderedset module

This module exposes the OrderedSet class, which is a collection of unique items that maintains the order in which the items were added. An OrderedSet (or its alias oset) behaves very similarly to Python’s builtin set object, the main difference being that an OrderedSet can efficiently lookup its items by index.

Example

>>> import ubelt as ub
>>> ub.oset([1, 2, 3])
OrderedSet([1, 2, 3])
>>> (ub.oset([1, 2, 3]) - {2}) | {2}
OrderedSet([1, 3, 2])
>>> [ub.oset([1, 2, 3])[i] for i in [1, 0, 2]]
[2, 1, 3]

As of version (0.8.5), ubelt contains its own internal copy of OrderedSet in order to reduce external dependencies. The original standalone implementation lives in https://github.com/LuminosoInsight/ordered-set.

The original documentation is as follows:

An OrderedSet is a custom MutableSet that remembers its order, so that every entry has an index that can be looked up.

Based on a recipe originally posted to ActiveState Recipes by Raymond Hettiger, and released under the MIT license.

class ubelt.orderedset.OrderedSet(iterable=None)[source]

Bases: MutableSet, Sequence

An OrderedSet is a custom MutableSet that remembers its order, so that every entry has an index that can be looked up.

Variables:
  • items (List[Any]) – internal ordered representation.

  • map (Dict[Any, int]) – internal mapping from items to indices.

Example

>>> OrderedSet([1, 1, 2, 3, 2])
OrderedSet([1, 2, 3])
Parameters:

iterable (None | Iterable) – input data

copy()[source]

Return a shallow copy of this object.

Returns:

OrderedSet

Example

>>> this = OrderedSet([1, 2, 3])
>>> other = this.copy()
>>> this == other
True
>>> this is other
False
add(key)[source]

Add key as an item to this OrderedSet, then return its index.

If key is already in the OrderedSet, return the index it already had.

Example

>>> oset = OrderedSet()
>>> oset.append(3)
0
>>> print(oset)
OrderedSet([3])
append(key)

Add key as an item to this OrderedSet, then return its index.

If key is already in the OrderedSet, return the index it already had.

Example

>>> oset = OrderedSet()
>>> oset.append(3)
0
>>> print(oset)
OrderedSet([3])
update(sequence)[source]

Update the set with the given iterable sequence, then return the index of the last element inserted.

Example

>>> oset = OrderedSet([1, 2, 3])
>>> oset.update([3, 1, 5, 1, 4])
4
>>> print(oset)
OrderedSet([1, 2, 3, 5, 4])
index(key)[source]

Get the index of a given entry, raising an IndexError if it’s not present.

key can be a non-string iterable of entries, in which case this returns a list of indices.

Example

>>> oset = OrderedSet([1, 2, 3])
>>> oset.index(2)
1
get_loc(key)

Get the index of a given entry, raising an IndexError if it’s not present.

key can be a non-string iterable of entries, in which case this returns a list of indices.

Example

>>> oset = OrderedSet([1, 2, 3])
>>> oset.index(2)
1
get_indexer(key)

Get the index of a given entry, raising an IndexError if it’s not present.

key can be a non-string iterable of entries, in which case this returns a list of indices.

Example

>>> oset = OrderedSet([1, 2, 3])
>>> oset.index(2)
1
pop()[source]

Remove and return the last element from the set.

Raises KeyError if the set is empty.

Returns:

Any

Example

>>> oset = OrderedSet([1, 2, 3])
>>> oset.pop()
3
discard(key)[source]

Remove an element. Do not raise an exception if absent.

The MutableSet mixin uses this to implement the .remove() method, which does raise an error when asked to remove a non-existent item.

Example

>>> oset = OrderedSet([1, 2, 3])
>>> oset.discard(2)
>>> print(oset)
OrderedSet([1, 3])
>>> oset.discard(2)
>>> print(oset)
OrderedSet([1, 3])
clear()[source]

Remove all items from this OrderedSet.

union(*sets)[source]

Combines all unique items. Each items order is defined by its first appearance.

Returns:

OrderedSet

Example

>>> oset = OrderedSet.union(OrderedSet([3, 1, 4, 1, 5]), [1, 3], [2, 0])
>>> print(oset)
OrderedSet([3, 1, 4, 5, 2, 0])
>>> oset.union([8, 9])
OrderedSet([3, 1, 4, 5, 2, 0, 8, 9])
>>> oset | {10}
OrderedSet([3, 1, 4, 5, 2, 0, 10])
intersection(*sets)[source]

Returns elements in common between all sets. Order is defined only by the first set.

Returns:

OrderedSet

Example

>>> from ubelt.orderedset import *  # NOQA
>>> oset = OrderedSet.intersection(OrderedSet([0, 1, 2, 3]), [1, 2, 3])
>>> print(oset)
OrderedSet([1, 2, 3])
>>> oset.intersection([2, 4, 5], [1, 2, 3, 4])
OrderedSet([2])
>>> oset.intersection()
OrderedSet([1, 2, 3])
difference(*sets)[source]

Returns all elements that are in this set but not the others.

Returns:

OrderedSet

Example

>>> OrderedSet([1, 2, 3]).difference(OrderedSet([2]))
OrderedSet([1, 3])
>>> OrderedSet([1, 2, 3]).difference(OrderedSet([2]), OrderedSet([3]))
OrderedSet([1])
>>> OrderedSet([1, 2, 3]) - OrderedSet([2])
OrderedSet([1, 3])
>>> OrderedSet([1, 2, 3]).difference()
OrderedSet([1, 2, 3])
issubset(other) bool[source]

Report whether another set contains this set.

Example

>>> OrderedSet([1, 2, 3]).issubset({1, 2})
False
>>> OrderedSet([1, 2, 3]).issubset({1, 2, 3, 4})
True
>>> OrderedSet([1, 2, 3]).issubset({1, 4, 3, 5})
False
issuperset(other) bool[source]

Report whether this set contains another set.

Example

>>> OrderedSet([1, 2]).issuperset([1, 2, 3])
False
>>> OrderedSet([1, 2, 3, 4]).issuperset({1, 2, 3})
True
>>> OrderedSet([1, 4, 3, 5]).issuperset({1, 2, 3})
False
symmetric_difference(other)[source]

Return the symmetric difference of two OrderedSets as a new set. That is, the new set will contain all elements that are in exactly one of the sets.

Their order will be preserved, with elements from self preceding elements from other.

Returns:

OrderedSet

Example

>>> this = OrderedSet([1, 4, 3, 5, 7])
>>> other = OrderedSet([9, 7, 1, 3, 2])
>>> this.symmetric_difference(other)
OrderedSet([4, 5, 9, 2])
difference_update(*sets)[source]

Update this OrderedSet to remove items from one or more other sets.

Example

>>> this = OrderedSet([1, 2, 3])
>>> this.difference_update(OrderedSet([2, 4]))
>>> print(this)
OrderedSet([1, 3])
>>> this = OrderedSet([1, 2, 3, 4, 5])
>>> this.difference_update(OrderedSet([2, 4]), OrderedSet([1, 4, 6]))
>>> print(this)
OrderedSet([3, 5])
intersection_update(other)[source]

Update this OrderedSet to keep only items in another set, preserving their order in this set.

Example

>>> this = OrderedSet([1, 4, 3, 5, 7])
>>> other = OrderedSet([9, 7, 1, 3, 2])
>>> this.intersection_update(other)
>>> print(this)
OrderedSet([1, 3, 7])
symmetric_difference_update(other)[source]

Update this OrderedSet to remove items from another set, then add items from the other set that were not present in this set.

Example

>>> this = OrderedSet([1, 4, 3, 5, 7])
>>> other = OrderedSet([9, 7, 1, 3, 2])
>>> this.symmetric_difference_update(other)
>>> print(this)
OrderedSet([4, 5, 9, 2])
ubelt.orderedset.oset

alias of OrderedSet