NEW UPDATE: In python 3.6+, you can use the new typed syntax and create a typing.NamedTuple. The new syntax supports most of the usual python class creation features (docstrings, default arguments, methods, etc etc are available as of 3.6.1; however multiple inheritance is not supported): import typing class Pokemon(typing.NamedTuple): “”” Attributes ———- name : str … Read more
You can subclass a namedtuple-produced class, but you need to study the generated class more closely. You’ll need to add another __slots__ attribute with the extra fields, update the _fields attribute, create new __repr__ and _replace methods (they hardcode the field list and class name) and add extra property objects for the additional fields. See … Read more
The way named tuples are constructed make inheritance from typing.NamedTuple classes as yet not possible. You’d have to write your own metaclass to extend the typing.NamedTupleMeta class to make subclassing work, and even then the class generated by collections.namedtuple() is just not built to extend. Instead, you want to use the new dataclasses module to … Read more
I use namedtuple’s _asdict method. However, it returns an OrderedDict which pprint won’t indent, so I convert it to a dict: >>> from collections import namedtuple >>> Busbar = namedtuple(‘Busbar’, ‘id name voltage’) >>> busbar = Busbar(id=102, name=”FACTORY”, voltage=21.8) With pprint and dict: >>> from pprint import pprint >>> pprint(dict(busbar._asdict())) {‘id’: 102, ‘name’: ‘FACTORY’, ‘voltage’: … Read more
namedtuple is a tuple so you can iterate as over normal tuple: >>> from collections import namedtuple >>> A = namedtuple(‘A’, [‘a’, ‘b’]) >>> for i in A(1,2): print i 1 2 but tuples are immutable so you cannot change the value if you need the name of the field you can use: >>> a … Read more
Per Python bug #24931: [__dict__] disappeared because it was fundamentally broken in Python 3, so it had to be removed. Providing __dict__ broke subclassing and produced odd behaviors. Revision that made the change Specifically, subclasses without __slots__ defined would behave weirdly: >>> Cluster = namedtuple(‘Cluster’, ‘x y’) >>> class Cluster2(Cluster): pass >>> vars(Cluster(1,2)) OrderedDict([(‘x’, 1), … Read more
Use: Data = namedtuple(“Data”, next(reader)) and omit the line: next(reader) Combining this with an iterative version based on martineau’s comment below, the example becomes for Python 2 import csv from collections import namedtuple from itertools import imap with open(“data_file.txt”, mode=”rb”) as infile: reader = csv.reader(infile) Data = namedtuple(“Data”, next(reader)) # get names from column headers … Read more
As an analogy (albeit an imperfect one), you can think of enum.Enum and namedtuple in python as enum and struct in C. In other words, enums are a way of aliasing values, while namedtuple is a way of encapsulating data by name. The two are not really interchangeable, and you can use enums as the … Read more
You can, but you have to override __new__ which is called implicitly before __init__: class Z(X): def __new__(cls, a, b, c, d): self = super(Z, cls).__new__(cls, a, b, c) self.d = d return self >>> z = Z(1, 2, 3, 4) >>> z Z(a=1, b=2, c=3) >>> z.d 4 But d will be just an … Read more
namedtuple() is a factory function for tuple subclasses. Here, ‘whatsmypurpose’is the type name. When you create a named tuple, a class with this name (whatsmypurpose) gets created internally. You can notice this by using the verbose argument like: Point=namedtuple(‘whatsmypurpose’,[‘x’,’y’], verbose=True) Also you can try type(p) to verify this.