Cawdrey¶

Several useful custom dictionaries for Python 📖 🐍

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Highlights¶

frozendict: An immutable dictionary that cannot be changed after creation.
FrozenOrderedDict: An immutable OrderedDict where the order of keys is preserved, but that cannot be changed after creation.
AlphaDict: A FrozenOrderedDict where the keys are stored in alphabetical order.
bdict: A dictionary where key, value pairs are stored both ways round.
Tally: A subclass of collections.Counter with additional methods.
HeaderMapping: A collections.abc.MutableMapping which supports duplicate, case-insentive keys.

This package also provides two base classes for creating your own custom dictionaries:

FrozenBase: An Abstract Base Class for frozen dictionaries.
MutableBase: An Abstract Base Class for mutable dictionaries.

Other Dictionary Packages¶

If you’re looking to unflatten a dictionary, such as to go from this:

{"foo.bar": "val"}

to this:

{"foo": {"bar": "val"}}

check out unflatten, flattery or morph to accomplish that.

indexed provides an OrederedDict where the values can be accessed by their index as well as by their keys.

There’s also python-benedict, which provides a custom dictionary with keylist/keypath support, I/O shortcuts (Base64, CSV, JSON, TOML, XML, YAML, pickle, query-string) and many utilities.

Installation¶

python3 -m pip install cawdrey --user

First add the required channels

conda config --add channels https://conda.anaconda.org/conda-forge
conda config --add channels https://conda.anaconda.org/domdfcoding

Then install

conda install cawdrey

python3 -m pip install git+https://github.com/domdfcoding/cawdrey@master --user

Contents¶

AlphaDict¶

Provides AlphaDict, a frozen OrderedDict where the keys are stored alphabetically.

Classes:

AlphaDict([seq])

Initialize an immutable, alphabetised dictionary.

Functions:

alphabetical_dict(**kwargs)

Returns an OrderedDict with the keys sorted alphabetically.

class AlphaDict(seq=None, **kwargs)[source]¶

Bases: FrozenOrderedDict[~KT, ~VT]

Initialize an immutable, alphabetised dictionary.

The signature is the same as regular dictionaries.

AlphaDict() -> new empty AlphaDict
AlphaDict(mapping) -> new AlphaDict initialized from a mapping object’s (key, value) pairs
AlphaDict(iterable) -> new AlphaDict initialized as if via:
d = {} for k, v in iterable: d[k] = v
AlphaDict(**kwargs) -> new AlphaDict initialized with the name=value pairs in the keyword argument list.
For example:
AlphaDict(one=1, two=2)

alphabetical_dict(**kwargs)[source]¶

Returns an OrderedDict with the keys sorted alphabetically.

Parameters: kwargs

bdict¶

class bdict(seq=None, **kwargs)[source]¶

Bases: UserDict

Returns a new dictionary initialized from an optional positional argument, and a possibly empty set of keyword arguments.

Each key: value pair is entered into the dictionary in both directions, so you can perform lookups with either the key or the value.

If no positional argument is given, an empty dictionary is created.

If a positional argument is given and it is a mapping object, a dictionary is created with the same key-value pairs as the mapping object. Otherwise, the positional argument must be an iterable object. Each item in the iterable must itself be an iterable with exactly two objects. The first object of each item becomes a key in the new dictionary, and the second object the corresponding value.

If keyword arguments are given, the keyword arguments and their values are added to the dictionary created from the positional argument.

If an attempt is made to add a key or value that already exists in the dictionary a ValueError will be raised.

Keys or values of None, True and False will be stored internally as "_None", "_True" and "_False" respectively

Methods:

`__contains__`(key)	Return `key in self`.
`__delitem__`(key)	Delete `self[key]`.
`__getitem__`(key)	Return `self[key]`.
`__setitem__`(key, val)	Set `self[key]` to `value`.
`clear`()	Removes all items from the `bdict`.
`get`(k[, default])	Return the value for `k` if `k` is in the dictionary, else `default`.
`items`()	Returns a set-like object providing a view on the `bdict`'s items.
`keys`()	Returns a set-like object providing a view on the `bdict`'s keys.
`values`()	Returns an object providing a view on the `bdict`'s values.

__contains__(key)[source]¶

Return key in self.

Parameters: key (object)
Return type: bool

__delitem__(key)[source]¶

Delete self[key].

Parameters: key (~KT)

__getitem__(key)[source]¶

Return self[key].

Parameters: key (~KT)
Return type: ~VT

__setitem__(key, val)[source]¶

Set self[key] to value.

Parameters

key
val

clear()[source]¶: Removes all items from the bdict.

get(k, default=None)[source]¶

Return the value for k if k is in the dictionary, else default.

Parameters

k – The key to return the value for.
default – The value to return if key is not in the dictionary. Default None.

Overloads

get(k: ~KT) -> Optional[~VT]
get(k: ~KT, default: Union[~VT, ~T] ) -> Union[~VT, ~T]

items()[source]¶

Returns a set-like object providing a view on the bdict's items.

Return type: AbstractSet[Tuple[~KT, ~VT]]

keys()[source]¶

Returns a set-like object providing a view on the bdict's keys.

Return type: AbstractSet[~KT]

values()[source]¶

Returns an object providing a view on the bdict's values.

Return type: ValuesView[~VT]

frozendict¶

About¶

frozendict is an immutable wrapper around dictionaries that implements the complete mapping interface. It can be used as a drop-in replacement for dictionaries where immutability is desired.

Of course this is Python, and you can still poke around the object’s internals if you want.

The frozendict constructor mimics dict, and all of the expected interfaces (iter, len, repr, hash, getitem) are provided. Note that a frozendict does not guarantee the immutability of its values, so the utility of the hash method is restricted by usage.

The only difference is that the copy() method of frozendict takes variable keyword arguments, which will be present as key/value pairs in the new, immutable copy.

Usage¶

>>> from cawdrey import frozendict
>>>
>>> fd = frozendict({ 'hello': 'World' })
>>>
>>> print fd
<frozendict {'hello': 'World'}>
>>>
>>> print fd['hello']
'World'
>>>
>>> print fd.copy(another='key/value')
<frozendict {'hello': 'World', 'another': 'key/value'}>
>>>

In addition, frozendict supports the + and - operands. If you add a dict-like object, a new frozendict will be returned, equal to the old frozendict updated with the other object. Example:

>>> frozendict({"Sulla": "Marco", 2: 3}) + {"Sulla": "Marò", 4: 7}
<frozendict {'Sulla': 'Marò', 2: 3, 4: 7}>
>>>

You can also subtract an iterable from a frozendict. A new frozendict will be returned, without the keys that are in the iterable. Examples:

>>> frozendict({"Sulla": "Marco", 2: 3}) - {"Sulla": "Marò", 4: 7}
<frozendict {'Sulla': 'Marco', 2: 3}>
>>> frozendict({"Sulla": "Marco", 2: 3}) - [2, 4]
<frozendict {'Sulla': 'Marco'}>
>>>

Some other examples:

>>> from cawdrey import frozendict
>>> fd = frozendict({"Sulla": "Marco", "Hicks": "Bill"})
>>> print(fd)
<frozendict {'Sulla': 'Marco', 'Hicks': 'Bill'}>
>>> print(fd["Sulla"])
Marco
>>> fd["Bim"]
KeyError: 'Bim'
>>> len(fd)
2
>>> "Sulla" in fd
True
>>> "Sulla" not in fd
False
>>> "Bim" in fd
False
>>> hash(fd)
835910019049608535
>>> fd_unhashable = frozendict({1: []})
>>> hash(fd_unhashable)
TypeError: unhashable type: 'list'
>>> fd2 = frozendict({"Hicks": "Bill", "Sulla": "Marco"})
>>> print(fd2)
<frozendict {'Hicks': 'Bill', 'Sulla': 'Marco'}>
>>> fd2 is fd
False
>>> fd2 == fd
True
>>> frozendict()
<frozendict {}>
>>> frozendict(Sulla="Marco", Hicks="Bill")
<frozendict {'Sulla': 'Marco', 'Hicks': 'Bill'}>
>>> frozendict((("Sulla", "Marco"), ("Hicks", "Bill")))
<frozendict {'Sulla': 'Marco', 'Hicks': 'Bill'}>
>>> fd.get("Sulla")
'Marco'
>>> print(fd.get("God"))
None
>>> tuple(fd.keys())
('Sulla', 'Hicks')
>>> tuple(fd.values())
('Marco', 'Bill')
>>> tuple(fd.items())
(('Sulla', 'Marco'), ('Hicks', 'Bill'))
>>> iter(fd)
<dict_keyiterator object at 0x7feb75c49188>
>>> frozendict.fromkeys(["Marco", "Giulia"], "Sulla")
<frozendict {'Marco': 'Sulla', 'Giulia': 'Sulla'}>
>>> fd["Sulla"] = "Silla"
TypeError: 'frozendict' object does not support item assignment
>>> del fd["Sulla"]
TypeError: 'frozendict' object does not support item deletion
>>> fd.clear()
AttributeError: 'frozendict' object has no attribute 'clear'
>>> fd.pop("Sulla")
AttributeError: 'frozendict' object has no attribute 'pop'
>>> fd.popitem()
AttributeError: 'frozendict' object has no attribute 'popitem'
>>> fd.setdefault("Sulla")
AttributeError: 'frozendict' object has no attribute 'setdefault'
>>> fd.update({"Bim": "James May"})
AttributeError: 'frozendict' object has no attribute 'update'

API Reference¶

class frozendict(*args, **kwargs)[source]¶

Bases: FrozenBase[~KT, ~VT]

An immutable wrapper around dictionaries that implements the complete collections.abc.Mapping interface. It can be used as a drop-in replacement for dictionaries where immutability is desired.

Methods:

`__add__`(other, args, *kwargs)	If you add a dict-like object, a new frozendict will be returned, equal to the old frozendict updated with the other object.
`__and__`(other, args, *kwargs)	Returns a new `frozendict`, that is the intersection between `self` and `other`.
`__sub__`(other, args, *kwargs)	The method will create a new `frozendict`, result of the subtraction by other.
`copy`(args, *kwargs)	Return a copy of the dictionary.
`sorted`(*args[, by])	Return a new `frozendict`, with the element insertion sorted.

__add__(other, *args, **kwargs)[source]¶: If you add a dict-like object, a new frozendict will be returned, equal to the old frozendict updated with the other object.

__and__(other, *args, **kwargs)[source]¶

Returns a new frozendict, that is the intersection between self and other.

If other is a dict-like object, the intersection will contain only the items in common.

If other is another iterable, the intersection will contain the items of self which keys are in other.

Iterables of pairs are not managed differently. This is for consistency.

Beware! The final order is dictated by the order of other. This allows the coder to change the order of the original frozendict.

The last two behaviours breaks voluntarily the dict.items() API, for consistency and practical reasons.

__sub__(other, *args, **kwargs)[source]¶

The method will create a new frozendict, result of the subtraction by other.

If other is a dict-like, the result will have the items of the frozendict that are not in common with other.

If other is another type of iterable, the result will have the items of frozendict without the keys that are in other.

copy(*args, **kwargs)[source]¶

Return a copy of the dictionary.

Return type: ~_D

sorted(*args, by='keys', **kwargs)[source]¶

Return a new frozendict, with the element insertion sorted. The signature is the same as the builtin sorted function, except for the additional parameter by, that is 'keys' by default and can also be 'values' and 'items'. So the resulting frozendict can be sorted by keys, values or items.

If you want more complicated sorts read the documentation of sorted.

The the parameters passed to the key function are the keys of the frozendict if by = "keys", and are the items otherwise.

Note

Sorting by keys and items achieves the same effect. The only difference is when you want to customize the sorting passing a custom key function. You could achieve the same result using by = "values", since also sorting by values passes the items to the key function. But this is an implementation detail and you should not rely on it.

Copyright¶

Based on https://github.com/slezica/python-frozendict and https://github.com/mredolatti/python-frozendict .
Copyright (c) 2012 Santiago Lezica
Licensed under the MIT License:

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Also based on https://github.com/Marco-Sulla/python-frozendict
Copyright (c) Marco Sulla
Licensed under the GNU Lesser General Public License Version 3

FrozenOrderedDict¶

About¶

FrozenOrderedDict is a immutable wrapper around an OrderedDict. It is similar to frozendict, and with regards to immutability it solves the same problems:

Because dictionaries are mutable, they are not hashable and cannot be used in sets or as dictionary keys.

Nasty bugs can and do occur when mutable data structures are passed around.

It can be initialized just like a dict or OrderedDict. Once instantiated, an instance of FrozenOrderedDict cannot be altered, since it does not implement the MutableMapping interface.

FrozenOrderedDict implements the Mapping interface, so can be used like a normal dictionary in most cases.

In order to modify the contents of a FrozenOrderedDict, a new instance must be created. The easiest way to do that is by calling the .copy() method. It will return a new instance of FrozenOrderedDict initialized using the following steps:

A copy of the wrapped OrderedDict instance will be created.

If any arguments or keyword arguments are passed to the .copy() method, they will be used to create another OrderedDict instance, which will then be used to update the copy made in step #1.

Finally, self.__class__() will be called, passing the copy as the only argument.

API Reference¶

class FrozenOrderedDict(*args, **kwargs)[source]¶

Bases: FrozenBase[~KT, ~VT]

An immutable OrderedDict. It can be used as a drop-in replacement for dictionaries where immutability is desired.

Methods:

`__contains__`(key)	Return `key in self`.
`__getitem__`(key)	Return `self[key]`.
`copy`(args, *kwargs)	Return a copy of the `FrozenOrderedDict`.
`get`(k[, default])	Return the value for `k` if `k` is in the dictionary, else `default`.
`items`()	Returns a set-like object providing a view on the `FrozenOrderedDict`'s items.
`keys`()	Returns a set-like object providing a view on the `FrozenOrderedDict`'s keys.
`values`()	Returns an object providing a view on the `FrozenOrderedDict`'s values.

__contains__(key)[source]¶

Return key in self.

Parameters: key (object)
Return type: bool

__getitem__(key)[source]¶

Return self[key].

Parameters: key (~KT)
Return type: ~VT

copy(*args, **kwargs)[source]¶

Return a copy of the FrozenOrderedDict.

Parameters

args
kwargs

get(k, default=None)[source]¶

Return the value for k if k is in the dictionary, else default.

Parameters

k – The key to return the value for.
default – The value to return if key is not in the dictionary. Default None.

Overloads

get(k: ~KT) -> Optional[~VT]
get(k: ~KT, default: Union[~VT, ~T] ) -> Union[~VT, ~T]

items()[source]¶

Returns a set-like object providing a view on the FrozenOrderedDict's items.

Return type: AbstractSet[Tuple[~KT, ~VT]]

keys()[source]¶

Returns a set-like object providing a view on the FrozenOrderedDict's keys.

Return type: AbstractSet[~KT]

values()[source]¶

Returns an object providing a view on the FrozenOrderedDict's values.

Return type: ValuesView[~VT]

Copyright¶

Based on https://github.com/slezica/python-frozendict and https://github.com/mredolatti/python-frozendict .
Copyright (c) 2012 Santiago Lezica
Licensed under the MIT License:

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Also based on https://github.com/Marco-Sulla/python-frozendict
Copyright (c) Marco Sulla
Licensed under the GNU Lesser General Public License Version 3

Also based on https://github.com/wsmith323/frozenordereddict
Copyright (c) 2015 Warren Smith
Licensed under the MIT License:

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

HeaderMapping¶

collections.abc.MutableMapping which supports duplicate, case-insentive keys.

New in version 0.4.0.

Classes:

HeaderMapping()

Provides a MutableMapping interface to a list of headers, such as those used in an email message.

class HeaderMapping[source]¶

Bases: MutableMapping[str, ~VT]

Provides a MutableMapping interface to a list of headers, such as those used in an email message.

NonelessDict¶

About¶

NonelessDict is a wrapper around dict that will check if a value is None/empty/False, and not add the key in that case.

The class has a method set_with_strict_none_check() that can be used to set a value and check only for None values.

NonelessOrderedDict is based on NonelessDict and OrderedDict, so the order of key insertion is preserved.

API Reference¶

Classes:

`NonelessDict`(args, *kwargs)	A wrapper around dict that will check if a value is `None`/empty/`False`, and not add the key in that case.
`NonelessOrderedDict`(args, *kwargs)	A wrapper around OrderedDict that will check if a value is None/empty/False, and not add the key in that case.

Data:

`_ND`	Invariant `TypeVar` bound to `cawdrey.nonelessdict.NonelessDict`.
`_NOD`	Invariant `TypeVar` bound to `cawdrey.nonelessdict.NonelessOrderedDict`.

class NonelessDict(*args, **kwargs)[source]¶

Bases: MutableBase[~KT, ~VT]

A wrapper around dict that will check if a value is None/empty/False, and not add the key in that case.

Use the set_with_strict_none_check() method to check only for None.

Methods:

`__setitem__`(key, value)	Set `self[key]` to `value`.
`copy`(**add_or_replace)	Return a copy of the dictionary.
`set_with_strict_none_check`(key, value)	Set `key` in the dictionary to `value`, but skipping `None` values.

__setitem__(key, value)[source]¶: Set self[key] to value.

copy(**add_or_replace)[source]¶

Return a copy of the dictionary.

Return type: ~_ND

set_with_strict_none_check(key, value)[source]¶

Set key in the dictionary to value, but skipping None values.

Parameters

key (~KT)
value (Optional[~VT])

class NonelessOrderedDict(*args, **kwargs)[source]¶

Bases: MutableBase[~KT, ~VT]

A wrapper around OrderedDict that will check if a value is None/empty/False, and not add the key in that case. Use the set_with_strict_none_check function to check only for None

Methods:

`__setitem__`(key, value)	Set `self[key]` to `value`.
`copy`(args, *kwargs)	Return a copy of the dictionary.
`set_with_strict_none_check`(key, value)	Set `key` in the dictionary to `value`, but skipping `None` values.

__setitem__(key, value)[source]¶: Set self[key] to value.

copy(*args, **kwargs)[source]¶

Return a copy of the dictionary.

Return type: ~_NOD

set_with_strict_none_check(key, value)[source]¶

Set key in the dictionary to value, but skipping None values.

Parameters

key (~KT)
value (Optional[~VT])

_ND = TypeVar(_ND, bound=NonelessDict)¶

Type: TypeVar

Invariant TypeVar bound to cawdrey.nonelessdict.NonelessDict.

_NOD = TypeVar(_NOD, bound=NonelessOrderedDict)¶

Type: TypeVar

Invariant TypeVar bound to cawdrey.nonelessdict.NonelessOrderedDict.

Copyright¶

Based on https://github.com/slezica/python-frozendict and https://github.com/jerr0328/python-helpfuldicts .
Copyright (c) 2012 Santiago Lezica
Licensed under the MIT License:

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Tally¶

Subclass of collections.Counter with additional methods.

New in version 0.3.0.

Data:

`_F`	Invariant `TypeVar` constrained to `float`, `int` and `numbers.Real`.

Classes:

`SupportsMostCommon`	`typing.Protocol` for classes which support a `collections.Counter`-like `collections.Counter.most_common()` method.
`Tally`([iterable])	Subclass of `collections.Counter` with additional methods.
`Percentage`	Provides a dictionary interface, but with `collections.Counter`’s `collections.Counter.most_common()` method.

_F = TypeVar(_F, float, int, Real)¶

Type: TypeVar

Invariant TypeVar constrained to float, int and numbers.Real.

protocol SupportsMostCommon[source]¶

Bases: Protocol[~KT]

typing.Protocol for classes which support a collections.Counter-like collections.Counter.most_common() method.

This protocol is runtime checkable.

Classes that implement this protocol must have the following methods / attributes:

items()[source]¶

Returns an iterator over the mapping’s items (as (key, value) pairs).

Return type: Iterable[Tuple[~KT, float]]

most_common(n=None)[source]¶

List the n most common elements and their counts from the most common to the least. If n is None then list all element counts.

>>> Counter('abracadabra').most_common(3)
[('a', 5), ('b', 2), ('r', 2)]

Parameters: n (Optional[int]) – Default None.
Return type: Union[List[Tuple[~KT, float]], List[Tuple[~KT, int]]]

class Tally(iterable=None, /, **kwds)[source]¶

Bases: Counter[~KT]

Subclass of collections.Counter with additional methods.

New in version 0.3.0.

Methods:

`as_percentage`()	Returns the `Tally` as a `collections.OrderedDict` comprising the count for each element as a percentage of the sum of all elements.
`get_percentage`(item[, default])	Returns the count for `item`, as a percentage of the sum of all elements.
`most_common`([n])	List the `n` most common elements and their counts from the most common to the least.

Attributes:

total

Returns the total count for all elements.

as_percentage()[source]¶

Returns the Tally as a collections.OrderedDict comprising the count for each element as a percentage of the sum of all elements.

Important

The sum of the dictionary’s values may not add up to exactly 1.0 due to limitations of floating-point numbers.

Return type: Percentage[~KT]

property total¶

Returns the total count for all elements.

Return type: int

get_percentage(item, default=None)[source]¶

Returns the count for item, as a percentage of the sum of all elements.

Parameters

item (~KT)
default (Optional[~_F]) – A default percentage (as a float) to return if item is not in the dictionary. Default None.

Return type

Union[None, ~_F, float]

Overloads

get_percentage(item: ~KT) -> Optional[float]
get_percentage(item: ~KT, default: ~_F) -> Union[~_F, float]

most_common(n=None)[source]¶

List the n most common elements and their counts from the most common to the least. If n is None then list all element counts.

>>> Tally('abracadabra').most_common(3)
[('a', 5), ('b', 2), ('r', 2)]

Parameters: n (Optional[int]) – Default None.
Return type: List[Tuple[~KT, int]]

class Percentage[source]¶

Bases: Dict[~KT, float]

Provides a dictionary interface, but with collections.Counter’s collections.Counter.most_common() method.

Represents the return type of cawdrey.tally.Tally.as_percentage().

Methods:

most_common([n])

List the n most common elements and their counts from the most common to the least.

most_common(n=None)[source]¶

List the n most common elements and their counts from the most common to the least. If n is None then list all element counts.

>>> Tally('abracadabra').as_percentage().most_common(3)
[('a', 0.45454545454545453), ('b', 0.18181818181818182), ('r', 0.18181818181818182)]

Parameters: n (Optional[int]) – Default None.
Return type: List[Tuple[~KT, float]]

Base Classes¶

About¶

FrozenBase is the base class for frozendict and FrozenOrderedDict. If you wish to construct your own frozen dictionary classes, you may inherit from this class.

API Reference¶

Classes:

`DictWrapper`(args, *kwds)	Abstract Mixin class for classes that wrap a dict object or similar.
`FrozenBase`(args, *kwargs)	Abstract Base Class for Frozen dictionaries.
`MutableBase`(args, *kwargs)	Abstract Base Class for mutable dictionaries.

Data:

`KT`	Invariant `TypeVar`.
`T`	Invariant `TypeVar`.
`VT`	Invariant `TypeVar`.
`_D`	Invariant `TypeVar` bound to `cawdrey.base.DictWrapper`.

class DictWrapper(*args, **kwds)[source]¶

Bases: Mapping[~KT, ~VT]

Abstract Mixin class for classes that wrap a dict object or similar.

Methods:

`__contains__`(key)	Return `key in self`.
`__getitem__`(key)	Return `self[key]`.
`__iter__`()	Iterates over the dictionary’s keys.
`__len__`()	Returns the number of keys in the dictionary.
`__repr__`()	Return a string representation of the `DictWrapper`.
`copy`(args, *kwargs)	Return a copy of the dictionary.
`get`(k[, default])	Return the value for `k` if `k` is in the dictionary, else `default`.
`items`()	Returns a set-like object providing a view on the dictionary’s items.
`keys`()	Returns a set-like object providing a view on the dictionary’s keys.
`values`()	Returns an object providing a view on the `bdict`'s values.

__contains__(key)[source]¶

Return key in self.

Parameters: key (object)
Return type: bool

__getitem__(key)[source]¶

Return self[key].

Parameters: key (~KT)
Return type: ~VT

__iter__()[source]¶

Iterates over the dictionary’s keys.

Return type: Iterator[~KT]

__len__()[source]¶

Returns the number of keys in the dictionary.

Return type: int

__repr__()[source]¶

Return a string representation of the DictWrapper.

Return type: str

abstract copy(*args, **kwargs)[source]¶

Return a copy of the dictionary.

Return type: ~_D

get(k, default=None)[source]¶

Return the value for k if k is in the dictionary, else default.

Parameters

k – The key to return the value for.
default – The value to return if key is not in the dictionary. Default None.

Overloads

get(k: ~KT) -> Optional[~VT]
get(k: ~KT, default: Union[~VT, ~T] ) -> Union[~VT, ~T]

items()[source]¶

Returns a set-like object providing a view on the dictionary’s items.

Return type: AbstractSet[Tuple[~KT, ~VT]]

keys()[source]¶

Returns a set-like object providing a view on the dictionary’s keys.

Return type: AbstractSet[~KT]

values()[source]¶

Returns an object providing a view on the bdict's values.

Return type: ValuesView[~VT]

class FrozenBase(*args, **kwargs)[source]¶

Bases: DictWrapper[~KT, ~VT]

Abstract Base Class for Frozen dictionaries.

Used by frozendict and FrozenOrderedDict.

Custom subclasses must implement at a minimum __init__, copy, fromkeys.

Methods:

fromkeys(iterable[, value])

Create a new dictionary with keys from iterable and values set to value.

classmethod fromkeys(iterable, value=None)[source]¶

Create a new dictionary with keys from iterable and values set to value.

Return type

FrozenBase[~KT, ~VT]

Overloads

fromkeys(iterable ) -> FrozenBase[KT, Any]
fromkeys(iterable, value: ~VT) -> FrozenBase[KT, VT]

KT = TypeVar(KT)¶

Type: TypeVar

Invariant TypeVar.

typing.TypeVar used for annotating key types in mappings.

class MutableBase(*args, **kwargs)[source]¶

Bases: DictWrapper[~KT, ~VT], MutableMapping[~KT, ~VT]

Abstract Base Class for mutable dictionaries.

Used by NonelessDict and NonelessOrderedDict.

Custom subclasses must implement at a minimum __init__, copy, fromkeys.

Methods:

`__delitem__`(key)	Delete `self[key]`.
`__setitem__`(key, value)	Set `self[key]` to `value`.
`fromkeys`(iterable[, value])	Create a new dictionary with keys from iterable and values set to value.

__delitem__(key)[source]¶: Delete self[key].

__setitem__(key, value)[source]¶: Set self[key] to value.

classmethod fromkeys(iterable, value=None)[source]¶

Create a new dictionary with keys from iterable and values set to value.

Return type

MutableBase[~KT, ~VT]

Overloads

fromkeys(iterable ) -> MutableBase[KT, Any]
fromkeys(iterable, value: ~VT) -> MutableBase[KT, VT]

T = TypeVar(T)¶

Type: TypeVar

Invariant TypeVar.

VT = TypeVar(VT)¶

Type: TypeVar

Invariant TypeVar.

typing.TypeVar used for annotating value types in mappings.

_D = TypeVar(_D, bound=DictWrapper)¶

Type: TypeVar

Invariant TypeVar bound to cawdrey.base.DictWrapper.

Functions¶

General utility functions.

Functions:

search_dict(dictionary, regex)

Return the subset of the dictionary whose keys match the regex.

search_dict(dictionary, regex)[source]¶

Return the subset of the dictionary whose keys match the regex.

Parameters

dictionary (Mapping[str, Any])
regex (Union[str, Pattern])

Return type

Dict[str, Any]

Contributing¶

Cawdrey uses tox to automate testing and packaging, and pre-commit to maintain code quality.

Install pre-commit with pip and install the git hook:

python -m pip install pre-commit
pre-commit install

Coding style¶

formate is used for code formatting.

It can be run manually via pre-commit:

pre-commit run formate -a

Or, to run the complete autoformatting suite:

pre-commit run -a

Automated tests¶

Tests are run with tox and pytest. To run tests for a specific Python version, such as Python 3.6:

tox -e py36

To run tests for all Python versions, simply run:

tox

Type Annotations¶

Type annotations are checked using mypy. Run mypy using tox:

tox -e mypy

Build documentation locally¶

The documentation is powered by Sphinx. A local copy of the documentation can be built with tox:

tox -e docs

Downloading source code¶

The Cawdrey source code is available on GitHub, and can be accessed from the following URL: https://github.com/domdfcoding/cawdrey

If you have git installed, you can clone the repository with the following command:

git clone https://github.com/domdfcoding/cawdrey

Cloning into 'cawdrey'...
remote: Enumerating objects: 47, done.
remote: Counting objects: 100% (47/47), done.
remote: Compressing objects: 100% (41/41), done.
remote: Total 173 (delta 16), reused 17 (delta 6), pack-reused 126
Receiving objects: 100% (173/173), 126.56 KiB | 678.00 KiB/s, done.
Resolving deltas: 100% (66/66), done.

Alternatively, the code can be downloaded in a ‘zip’ file by clicking:

Clone or download –> Download Zip

Downloading a ‘zip’ file of the source code¶

Building from source¶

The recommended way to build Cawdrey is to use tox:

tox -e build

The source and wheel distributions will be in the directory dist.

If you wish, you may also use pep517.build or another PEP 517-compatible build tool.

License¶

Cawdrey is licensed under the GNU Lesser General Public License v3.0

Permissions of this copyleft license are conditioned on making available complete source code of licensed works and modifications under the same license or the GNU GPLv3. Copyright and license notices must be preserved. Contributors provide an express grant of patent rights. However, a larger work using the licensed work through interfaces provided by the licensed work may be distributed under different terms and without source code for the larger work.

Permissions	Conditions	Limitations
Commercial use Modification Distribution Patent use Private use	License and copyright notice Disclose source State changes Same license (library)	Liability Warranty

See more information on choosealicense.com ➩

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 Everyone is permitted to copy and distribute verbatim copies
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View the Function Index or browse the Source Code.

Browse the GitHub Repository

And Finally:¶

Why “Cawdrey”?

`__contains__`(name)	Returns whether `name` is in the `HeaderMapping`.
`__delitem__`(name)	Delete all occurrences of a header, if present.
`__getitem__`(name)	Get a header value.
`__iter__`()	Returns an iterator over the keys in the `HeaderMapping`.
`__len__`()	Return the total number of keys, including duplicates.
`__repr__`()	Return a string representation of the `HeaderMapping`.
`__setitem__`(name, val)	Set the value of a header.
`get`(k[, default])	Get a header value.
`get_all`(k[, default])	Return a list of all the values for the named field.
`items`()	Get all the message’s header fields and values.
`keys`()	Return a list of all the message’s header field names.
`values`()	Return a list of all the message’s header values.