orderedattrdict 1.4.1

OrderedDict with attribute-style access

An ordered dictionary with attribute-style access.

Usage

AttrDict behaves exactly like collections.OrderedDict, but also allows keys to be accessed as attributes:

>>> from orderedattrdict import AttrDict
>>> conf = AttrDict()
>>> conf['z'] = 1
>>> assert conf.z == 1
>>> conf.y = 2
>>> assert conf['y'] == 2
>>> conf.x = 3
>>> assert conf.keys() == ['z', 'y', 'x']

NOTE: If the key clashes with an OrderedDict attribute or starts with __ (two underscores), you can’t access it as an attribute. For example:

>>> a = AttrDict(keys=1)
>>> a.keys
<bound method AttrDict.keys of AttrDict([('keys', 1)])>
>>> a['keys']
1

Load JSON preserving the order of keys:

>>> import json
>>> data = json.load(open('test.json'), object_pairs_hook=AttrDict)

Load YAML preserving the order of keys:

>>> import yaml
>>> from orderedattrdict.yamlutils import AttrDictYAMLLoader
>>> data = yaml.load(open('test.yaml'), Loader=AttrDictYAMLLoader)

Make PyYAML always load all dictionaries as AttrDict:

>>> from orderedattrdict.yamlutils import from_yaml
>>> yaml.add_constructor(u'tag:yaml.org,2002:map', from_yaml)
>>> yaml.add_constructor(u'tag:yaml.org,2002:omap', from_yaml)

json.dump, yaml.dump and yaml.safe_dump convert AttrDict into dictionaries, retaining the order:

>>> json.dumps(data)
>>> yaml.dump(data)

CounterAttrDict

CounterAttrDict provides a Counter with ordered keys and attribute-style access:

>>> from orderedattrdict import CounterAttrDict
>>> c = CounterAttrDict()
>>> c.x
0
>>> c.elements
<bound method CounterAttrDict.elements of CounterAttrDict()>
>>> c.x += 1
>>> c.y += 2
>>> c.most_common()
[('y', 2), ('x', 1)]
>>> list(c.elements())
['x', 'y', 'y']
>>> c.subtract(y=1)
>>> c
CounterAttrDict([('x', 1), ('y', 1)])

DefaultAttrDict

DefaultAttrDict provides a defaultdict with ordered keys and attribute-style access. This can be used with a list factory to collect items:

>>> from orderedattrdict import DefaultDict
>>> d = DefaultAttrDict(list)
>>> d.x.append(10)  # Append item without needing to initialise list
>>> d.x.append(20)
>>> sum(d.x)
30

or with a set to collect unique items:

>>> d = DefaultAttrDict(set)
>>> d.x.add(5)
>>> d.x.add(2)
>>> d.x.add(5)      # Duplicate item is ignored
>>> sum(d.x)
7

You can create a tree structure where you can set attributes in any level of the hierarchy using the above DefaultAttrDict:

>>> tree = lambda: DefaultAttrDict(tree)
>>> node = tree()
>>> node.x.y.z = 1
>>> node
DefaultAttrDict([('x', DefaultAttrDict([('y', DefaultAttrDict([('z', 1)]))]))])

Installation

This is a pure-Python package built for Python 2.7+ and Python 3.0+. To set up:

pip install orderedattrdict

Changelog

• 1.0: Basic implementation

• 1.1: Add utilities to load and save as YAML

• 1.2: Allow specific keys to be excluded from attribute access

• 1.3: Restore << merge tags for YAML

• 1.4.1: Add CounterAttrDict and DefaultAttrDict