CODEWITHSUNDEEP
python
canadadry
canadadry

Reputation: 8443

Can I overwrite the string form of a namedtuple?

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 ?

Upvotes: 48

Views: 16053

Answers (3)

Raymond Hettinger
Raymond Hettinger

Reputation: 226296

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)

Upvotes: 83

Serdalis
Serdalis

Reputation: 10489

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.

Upvotes: 4

Björn Pollex
Björn Pollex

Reputation: 76788

You can define a function for it:

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

and assign it to __str__:

Spoken.__str__ = print_loudness

Upvotes: 20

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