1.4. collections
— High-performance container datatypes¶
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collections.
namedtuple
(typename, field_names)¶ Returns a new tuple subclass named typename. The new subclass is used to create tuple-like objects that have fields accessible by attribute lookup as well as being indexable and iterable. Instances of the subclass also have a helpful docstring (with typename and field_names) and a helpful
__repr__()
method which lists the tuple contents in a name=value format.The field_names are a single string with each fieldname separated by whitespace and/or commas, for example
'x y'
or'x, y'
. Alternatively, field_names can be a sequence of strings such as['x', 'y']
.>>> # Basic example >>> Point = namedtuple('Point', ['x', 'y']) >>> p = Point(11, y=22) # instantiate with positional or keyword arguments >>> p[0] + p[1] # indexable like the plain tuple (11, 22) 33 >>> x, y = p # unpack like a regular tuple >>> x, y (11, 22) >>> p.x + p.y # fields also accessible by name 33 >>> p # readable __repr__ with a name=value style Point(x=11, y=22)
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class
collections.
OrderedDict
([items])¶ Return an instance of a dict subclass, supporting the usual dict methods. An OrderedDict is a dict that remembers the order that keys were first inserted. If a new entry overwrites an existing entry, the original insertion position is left unchanged. Deleting an entry and reinserting it will move it to the end.
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popitem
(last=True)¶ The
popitem()
method for ordered dictionaries returns and removes a(key, value)
pair. The pairs are returned in LIFO order if last is true or FIFO order if false.
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