Can I overwrite the string form of a namedtuple?

Question

For example:

>>> Spoken = namedtuple("Spoken", ["loudness", "pitch"])
>>> s = Spoken(loudness=90, pitch='high')
>>> str(s)
"Spoken(loudness=90, pitch='high')"

What I want is:

>>> str(s)
90

That is I want the string representation to display the loudness attribute.
Is this possible ?

Asked By: canadadry

||

Source

Answer 1

You can define a function for it:

def print_loudness(self):
    return str(self.loudness)

and assign it to __str__:

Spoken.__str__ = print_loudness

Answered By: Björn Pollex

Answer 2

Yes, it is not hard to do and there is an example for it in the namedtuple docs.

The technique is to make a subclass that adds its own str method:

>>> from collections import namedtuple
>>> class Spoken(namedtuple("Spoken", ["loudness", "pitch"])):
        __slots__ = ()
        def __str__(self):
            return str(self.loudness)

>>> s = Spoken(loudness=90, pitch='high')
>>> str(s)
'90'

Update:

You can also used typing.NamedTuple to get the same effect.

from typing import NamedTuple

class Spoken(NamedTuple):
    
    loudness: int
    pitch: str
    
    def __str__(self):
        return str(self.loudness)

Answered By: Raymond Hettinger

Answer 3

you can use code like this:

from collections import namedtuple

class SpokenTuple( namedtuple("Spoken", ["loudness", "pitch"]) ):

    def __str__(self):
        return str(self.loudness)

s = SpokenTuple(loudness=90, pitch='high')

print(str(s))

This will wrap namedtuple in a class of your choice which you then overload the str function too.

Answered By: Serdalis

Can I overwrite the string form of a namedtuple?

Question:

Answers: