# API Reference

## Protocol APIs

Changed in version 4.8.0: Previously, `ISized` was defined here, but now it is imported from `zope.interface.common.collections`. The definition is the same.

Similarly, `IReadSequence`, previously defined here, has been replaced with `zope.interface.common.sequence.IMinimalSequence`.

Caution

Before version 4.8.0, most of these interfaces served as documentation only, and were not implemented by the classes of this package. For example, `BTrees.OOBTree.BTree` did not implement IBTree. (The exceptions were the `IBTreeModule` and `IBTreeFamily` families of interfaces and implementations.)

Beginning with version 4.8.0, objects implement the expected interface; the `BTree` classes implement `IBTree`, the set classes implement the appropriate set interface and so on.

interface BTrees.Interfaces.IKeyed

  Extends: `BTrees.Interfaces.ICollection`

  has_key(key)

    Check whether the object has an item with the given key.

    Return a true value if the key is present, else a false value.

  keys(min=None, max=None, excludemin=False, excludemax=False)

    Return an `IMinimalSequence` containing the keys in the collection.

    The type of the `IMinimalSequence` is not specified. It could be a list or a tuple or some other type.

    All arguments are optional, and may be specified as keyword arguments, or by position.

    If a min is specified, then output is constrained to keys greater than or equal to the given min, and, if excludemin is specified and true, is further constrained to keys strictly greater than min. A min value of None is ignored. If min is None or not specified, and excludemin is true, the smallest key is excluded.

    If a max is specified, then output is constrained to keys less than or equal to the given max, and, if excludemax is specified and true, is further constrained to keys strictly less than max. A max value of None is ignored. If max is None or not specified, and excludemax is true, the largest key is excluded.

  maxKey(key=None)

    Return the maximum key.

    If a key argument if provided and not None, return the largest key that is less than or equal to the argument. Raise an exception if no such key exists.

  minKey(key=None)

    Return the minimum key.

    If a key argument if provided and not None, return the smallest key that is greater than or equal to the argument. Raise an exception if no such key exists.

interface BTrees.Interfaces.ISetMutable

  Extends: `BTrees.Interfaces.IKeyed`

  insert(key)

    Add the key (value) to the set.

    If the key was already in the set, return 0, otherwise return 1.

  remove(key)

    Remove the key from the set.

    Raises `KeyError` if key is not in the set.

  update(seq)

    Add the items from the given sequence to the set.

  __and__(other)

    Shortcut for `intersection()`

    Added in version 4.8.0.

  __iand__(other)

    As for `set.intersection_update()`: Update this object, keeping only elements found in both it and other.

    Added in version 4.8.0.

  __or__(other)

    Shortcut for `union()`

    Added in version 4.8.0.

  __ior__(other)

    As for `set.update()`: Update this object, adding elements from other.

    Added in version 4.8.0.

  __sub__(other)

    Shortcut for `difference()`

    Added in version 4.8.0.

  __isub__(other)

    As for `set.difference_update()`: Update this object, removing elements found in other.

    Added in version 4.8.0.

  isdisjoint(other)

    As for `set.isdisjoint()`: Return True if the set has no elements in common with other.

    Added in version 4.8.0.

  discard(key)

    As for `set.discard()`: Remove the key from the set, but only if it is present.

    Added in version 4.8.0.

  pop()

    As for `set.pop()`: Remove and return an arbitrary element; raise `KeyError` if the object is empty.

    Added in version 4.8.0.

  __ixor__(other)

    As for `set.symmetric_difference_update()`: Update this object, keeping only elements found in either set but not in both.

    Added in version 4.8.0.

interface BTrees.Interfaces.IKeySequence

  Extends: `BTrees.Interfaces.IKeyed`, `zope.interface.common.collections.ISized`

  __getitem__(index)

    Return the key in the given index position.

    This allows iteration with for loops and use in functions, like map and list, that read sequences.

interface BTrees.Interfaces.IMinimalDictionary

  Extends: `BTrees.Interfaces.IKeyed`, `zope.interface.common.collections.IMapping`

  Mapping operations.

  Changed in version 4.8.0: Now extends `zope.interface.common.collections.IMapping`.

  get(key, default)

    Get the value associated with the given key.

    Return the default if `has_key()` is false with the given key.

  __getitem__(key)

    Get the value associated with the given key.

    Raise `KeyError` if `has_key()` is false with the given key.

  __setitem__(key, value)

    Set the value associated with the given key.

  __delitem__(key)

    Delete the value associated with the given key.

    Raise class:KeyError if `has_key()` is false with the given key.

  values(min=None, max=None, excludemin=False, excludemax=False)

    Return a minimal sequence containing the values in the collection.

    Return value is an `IMinimalSequence`.

    The type of the `IMinimalSequence` is not specified. It could be a list or a tuple or some other type.

    All arguments are optional, and may be specified as keyword arguments, or by position.

    If a min is specified, then output is constrained to values whose keys are greater than or equal to the given min, and, if excludemin is specified and true, is further constrained to values whose keys are strictly greater than min. A min value of None is ignored. If min is None or not specified, and excludemin is true, the value corresponding to the smallest key is excluded.

    If a max is specified, then output is constrained to values whose keys are less than or equal to the given max, and, if excludemax is specified and true, is further constrained to values whose keys are strictly less than max. A max value of None is ignored. If max is None or not specified, and excludemax is true, the value corresponding to the largest key is excluded.

  items(min=None, max=None, excludemin=False, excludemax=False)

    Return an `IMinimalSequence` containing the items in the collection.

    An item is a 2-tuple, a `(key, value)` pair.

    The type of the `IMinimalSequence` is not specified. It could be a list or a tuple or some other type.

    All arguments are optional, and may be specified as keyword arguments, or by position.

    If a min is specified, then output is constrained to items whose keys are greater than or equal to the given min, and, if excludemin is specified and true, is further constrained to items whose keys are strictly greater than min. A min value of None is ignored. If min is None or not specified, and excludemin is true, the item with the smallest key is excluded.

    If a max is specified, then output is constrained to items whose keys are less than or equal to the given max, and, if excludemax is specified and true, is further constrained to items whose keys are strictly less than *max. A max value of None is ignored. If max is None or not specified, and excludemax is true, the item with the largest key is excluded.

interface BTrees.Interfaces.IDictionaryIsh

  Extends: `BTrees.Interfaces.IMinimalDictionary`

  update(collection)

    Add the items from the given collection object to the collection.

    The input collection must be a sequence of (key, value) 2-tuples, or an object with an ‘items’ method that returns a sequence of (key, value) pairs.

  byValue(minValue)

    Return a sequence of (value, key) pairs, sorted by value.

    Values < minValue are omitted and other values are “normalized” by the minimum value. This normalization may be a noop, but, for integer values, the normalization is division.

  setdefault(key, d)

    D.setdefault(k, d) -> D.get(k, d), also set D[k]=d if k not in D.

    Return the value like `get()` except that if key is missing, d is both returned and inserted into the dictionary as the value of k.

    Note that, unlike as for Python’s `dict.setdefault()`, d is not optional. Python defaults d to None, but that doesn’t make sense for mappings that can’t have None as a value (for example, an `IIBTree` can have only integers as values).

  pop(key, d)

    D.pop(k[, d]) -> v, remove key and return the corresponding value.

    If key is not found, d is returned if given, otherwise `KeyError` is raised.

  popitem()

    D.popitem() -> (k, v), remove and return some (key, value) pair as a 2-tuple; but raise KeyError if D is empty.

    Added in version 4.8.0.

interface BTrees.Interfaces.IMerge

  Object with methods for merging sets, buckets, and trees.

  These methods are supplied in modules that define collection classes with particular key and value types. The operations apply only to collections from the same module. For example, the `BTrees.IIBTree.IIBTree.union()` can only be used with `IIBTree`, `IIBucket`, `IISet`, and `IITreeSet`.

  The number protocols methods `__and__`, `__or__` and `__sub__` are provided by all the data structures. They are shortcuts for `intersection()`, `union()` and `difference()`.

  The implementing module has a value type. The `IOBTree` and `OOBTree` modules have object value type. The `IIBTree` and `OIBTree` modules have integer value types. Other modules may be defined in the future that have other value types.

  The individual types are classified into set (Set and TreeSet) and mapping (Bucket and BTree) types.

  difference(c1, c2)

    Return the keys or items in c1 for which there is no key in c2.

    If c1 is None, then None is returned. If c2 is None, then c1 is returned.

    If neither c1 nor c2 is None, the output is a Set if c1 is a Set or TreeSet, and is a Bucket if c1 is a Bucket or BTree.

    While c1 must be one of those types, c2 can be any Python iterable returning the correct types of objects.

    Changed in version 4.8.0: Add support for c2 to be an arbitrary iterable.

  union(c1, c2)

    Compute the Union of c1 and c2.

    If c1 is None, then c2 is returned, otherwise, if c2 is None, then c1 is returned.

    The output is a Set containing keys from the input collections.

    c1 and c2 can be any Python iterables returning the correct type of objects.

    Changed in version 4.8.0: Add support for arbitrary iterables.

  intersection(c1, c2)

    Compute the intersection of c1 and c2.

    If c1 is None, then c2 is returned, otherwise, if c2 is None, then c1 is returned.

    The output is a Set containing matching keys from the input collections.

    c1 and c2 can be any Python iterables returning the correct type of objects.

    Changed in version 4.8.0: Add support for arbitrary iterables.

interface BTrees.Interfaces.IIMerge

  Extends: `BTrees.Interfaces.IMerge`

  Merge collections with integer value type.

  A primary intent is to support operations with no or integer values, which are used as “scores” to rate indiviual keys. That is, in this context, a BTree or Bucket is viewed as a set with scored keys, using integer scores.

  weightedUnion(c1, c2, weight1=1, weight2=1)

    Compute the weighted union of c1 and c2.

    If c1 and c2 are None, the output is (0, None).

    If c1 is None and c2 is not None, the output is (weight2, c2).

    If c1 is not None and c2 is None, the output is (weight1, c1).

    Else, and hereafter, c1 is not None and c2 is not None.

    If c1 and c2 are both sets, the output is 1 and the (unweighted) union of the sets.

    Else the output is 1 and a Bucket whose keys are the union of c1 and c2’s keys, and whose values are:

        v1*weight1 + v2*weight2

        where:

          v1 is 0        if the key is not in c1
                1        if the key is in c1 and c1 is a set
                c1[key]  if the key is in c1 and c1 is a mapping

          v2 is 0        if the key is not in c2
                1        if the key is in c2 and c2 is a set
                c2[key]  if the key is in c2 and c2 is a mapping

    Note that c1 and c2 must be collections.

  weightedIntersection(c1, c2, weight1=1, weight2=1)

    Compute the weighted intersection of c1 and c2.

    If c1 and c2 are None, the output is (0, None).

    If c1 is None and c2 is not None, the output is (weight2, c2).

    If c1 is not None and c2 is None, the output is (weight1, c1).

    Else, and hereafter, c1 is not None and c2 is not None.

    If c1 and c2 are both sets, the output is the sum of the weights and the (unweighted) intersection of the sets.

    Else the output is 1 and a Bucket whose keys are the intersection of c1 and c2’s keys, and whose values are:

        v1*weight1 + v2*weight2

        where:

          v1 is 1        if c1 is a set
                c1[key]  if c1 is a mapping

          v2 is 1        if c2 is a set
                c2[key]  if c2 is a mapping

    Note that c1 and c2 must be collections.

interface BTrees.Interfaces.IMergeIntegerKey

  Extends: `BTrees.Interfaces.IMerge`

  `IMerge`-able objects with integer keys.

  Concretely, this means the types in `IOBTree` and `IIBTree`.

  multiunion(seq)

    Return union of (zero or more) integer sets, as an integer set.

    seq is a sequence of objects each convertible to an integer set. These objects are convertible to an integer set:

    - An integer, which is added to the union.

    - A Set or TreeSet from the same module (for example, an `BTrees.IIBTree.TreeSet` for `BTrees.IIBTree.multiunion()`). The elements of the set are added to the union.

    - A Bucket or BTree from the same module (for example, an `BTrees.IOBTree.IOBTree` for `BTrees.IOBTree.multiunion()`). The keys of the mapping are added to the union.

    - Any iterable Python object that iterates across integers. This will be slower than the above types.

    The union is returned as a Set from the same module (for example, `BTrees.IIBTree.multiunion()` returns an `BTrees.IIBTree.IISet`).

    The point to this method is that it can run much faster than doing a sequence of two-input `union()` calls. Under the covers, all the integers in all the inputs are sorted via a single linear-time radix sort, then duplicates are removed in a second linear-time pass.

    Changed in version 4.8.0: Add support for arbitrary iterables of integers.

### BTree Family APIs

interface BTrees.Interfaces.ISet

  Extends: `BTrees.Interfaces.ISetMutable`, `BTrees.Interfaces.IKeySequence`

  A set of unique items stored in a single persistent object.

interface BTrees.Interfaces.ITreeSet

  Extends: `BTrees.Interfaces.ISetMutable`

  A set of unique items stored in a tree of persistent objects.

interface BTrees.Interfaces.IBTree

  Extends: `BTrees.Interfaces.IDictionaryIsh`

  insert(key, value)

    Insert a key and value into the collection.

    If the key was already in the collection, then there is no change and 0 is returned.

    If the key was not already in the collection, then the item is added and 1 is returned.

    This method is here to allow one to generate random keys and to insert and test whether the key was there in one operation.

    A standard idiom for generating new keys will be:

        key = generate_key()
        while not t.insert(key, value):
            key=generate_key()

  __and__(other)

    Shortcut for `intersection()`

  __or__(other)

    Shortcut for `union()`

  __sub__(other)

    Shortcut for `difference()`

interface BTrees.Interfaces.IBTreeFamily

  the 64-bit or 32-bit family

  IF

    The IIntegerFloatBTreeModule for this family

  II

    The IIntegerIntegerBTreeModule for this family

  IO

    The IIntegerObjectBTreeModule for this family

  IU

    The IIntegerUnsignedBTreeModule for this family

  UF

    The IUnsignedFloatBTreeModule for this family

  UI

    The IUnsignedIntegerBTreeModule for this family

  UO

    The IUnsignedObjectBTreeModule for this family

  UU

    The IUnsignedUnsignedBTreeModule for this family

  OI

    The IObjectIntegerBTreeModule for this family

  OO

    The IObjectObjectBTreeModule for this family

  OU

    The IObjectUnsignedBTreeModule for this family

  maxint

    The maximum signed integer storable in this family

  maxuint

    The maximum unsigned integer storable in this family

  minint

    The minimum signed integer storable in this family

There are two families defined:

### Module APIs

interface BTrees.Interfaces.IBTreeModule

  These are available in all modules (IOBTree, OIBTree, OOBTree, IIBTree, IFBTree, LFBTree, LOBTree, OLBTree, and LLBTree).

  BTree

    The IBTree for this module.

    Also available as [prefix]BTree, as in IOBTree.

  Bucket

    The leaf-node data buckets used by the BTree.

    (IBucket is not currently defined in this file, but is essentially IDictionaryIsh, with the exception of __nonzero__, as of this writing.)

    Also available as [prefix]Bucket, as in IOBucket.

  TreeSet

    The ITreeSet for this module.

    Also available as [prefix]TreeSet, as in IOTreeSet.

  Set

    The ISet for this module: the leaf-node data buckets used by the TreeSet.

    Also available as [prefix]BTree, as in IOSet.

interface BTrees.Interfaces.IObjectObjectBTreeModule

  Extends: `BTrees.Interfaces.IBTreeModule`, `BTrees.Interfaces.IMerge`

  Keys, or set values, are objects; values are also objects.

  Object keys (and set values) must sort reliably (for instance, not on object id)! Homogenous key types recommended.

  Note that there’s no `family` attribute; all families include the OO flavor of BTrees.

  Describes OOBTree

interface BTrees.Interfaces.IIntegerObjectBTreeModule

  Extends: `BTrees.Interfaces._IMergeBTreeModule`

  Keys, or set values, are signed ints; values are objects.

  Describes IOBTree and LOBTree.

interface BTrees.Interfaces.IObjectIntegerBTreeModule

  Extends: `BTrees.Interfaces._IMergeBTreeModule`

  Keys, or set values, are objects; values are signed ints.

  Object keys (and set values) must sort reliably (for instance, not on object id)! Homogenous key types recommended.

  Describes OIBTree and OLBTree.

interface BTrees.Interfaces.IIntegerIntegerBTreeModule

  Extends: `BTrees.Interfaces._IMergeBTreeModule`, `BTrees.Interfaces.IMergeIntegerKey`

  Keys, or set values, are signed integers; values are signed integers.

  Describes IIBTree and LLBTree

interface BTrees.Interfaces.IIntegerFloatBTreeModule

  Extends: `BTrees.Interfaces._IMergeBTreeModule`

  Keys, or set values, are signed ints; values are floats.

  Describes IFBTree and LFBTree

## Utilities

## BTree Data Structure Variants

### Integer Keys

#### Float Values

#### Integer Values

#### Object Values

#### Unsigned Integer Values

### Long Integer Keys

#### Float Values

#### Long Integer Values

#### Object Values

#### Quad Unsigned Integer Values

### Object Keys

#### Integer Values

#### Long Integer Values

#### Object Values

#### Quad Unsigned Integer Values

#### Unsigned Integer Values

### Quad Unsigned Integer Keys

#### Float Values

#### Long Integer Values

#### Object Values

#### Quad Unsigned Integer Values

### Unsigned Integer Keys

#### Float Values

#### Integer Values

#### Object Values

#### Unsigned Integer Values