OrderedDefaultdict¶

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

Bases: OrderedDict

This class behaves as defaultdict from the collections module but maintaining the order of insertion.

It is usually called in our codebase using the following structure: my_list = utils.OrderedDefaultdict(list) The dict can then be filled straight away: my_list[2] = [1, 2, 3]

For example, >>> my_list = OrderedDefaultdict(list) >>> my_list[2] = [1, 2, 3] >>> my_list[1] [] >>> my_list[2] [1, 2, 3]

Note that from Python 3.8 this class should probably work as collections.defaultdict given that dicts now preserve the insertion order as a feature and the __reverse__ method is implemented in dicts.

Methods Summary

`clear`()
`copy`()
`fromkeys`(iterable[, value])	Create a new ordered dictionary with keys from iterable and values set to value.
`get`(key[, default])	Return the value for key if key is in the dictionary, else default.
`items`()
`keys`()
`move_to_end`(key[, last])	Move an existing element to the end (or beginning if last is false).
`pop`(key[,default])	If the key is not found, return the default if given; otherwise, raise a KeyError.
`popitem`([last])	Remove and return a (key, value) pair from the dictionary.
`setdefault`(key[, default])	Insert key with a value of default if key is not in the dictionary.
`update`([E, ]**F)	If E is present and has a .keys() method, then does: for k in E.keys(): D[k] = E[k] If E is present and lacks a .keys() method, then does: for k, v in E: D[k] = v In either case, this is followed by: for k in F: D[k] = F[k]
`values`()

Methods Documentation

clear() → None. Remove all items from od.¶

copy() → a shallow copy of od¶

classmethod fromkeys(iterable, value=None)¶: Create a new ordered dictionary with keys from iterable and values set to value.

get(key, default=None, /)¶: Return the value for key if key is in the dictionary, else default.

items() → a set-like object providing a view on D's items¶

keys() → a set-like object providing a view on D's keys¶

move_to_end(key, last=True)¶

Move an existing element to the end (or beginning if last is false).

Raise KeyError if the element does not exist.

pop(key[, default]) → v, remove specified key and return the corresponding value.¶: If the key is not found, return the default if given; otherwise, raise a KeyError.

popitem(last=True)¶

Remove and return a (key, value) pair from the dictionary.

Pairs are returned in LIFO order if last is true or FIFO order if false.

setdefault(key, default=None)¶

Insert key with a value of default if key is not in the dictionary.

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

update([E, ]**F) → None. Update D from mapping/iterable E and F.¶: If E is present and has a .keys() method, then does: for k in E.keys(): D[k] = E[k] If E is present and lacks a .keys() method, then does: for k, v in E: D[k] = v In either case, this is followed by: for k in F: D[k] = F[k]

values() → an object providing a view on D's values¶