Namedtuple in Python

Python supports a type of container dictionary called “namedtuple()” present in the module “collections“. In this article, we are going to review how to Create a NameTuple and operations enabled NamedTuple.

What is NamedTuple in Python?

In Python, NamedTuple is present inside the collections module. It provides a way to create simple, lightweight data structures similar to a class, but without the overhead of defining a full class. similar as dictionaries, they contain keys that are hashed to a particular value. On the contrary, it supports both access from key-value and iteration, the functionality that dictionaries lack.

Python NamedTuple Syntax

namedtuple(typename, field_names)

typename – The name of the namedtuple.

field_names – The list of attributes stored in the namedtuple.

Example: Code implementation of NamedTuple is shown in Python.

Python

# Python code to demonstrate namedtuple()
from collections import namedtuple

# Declaring namedtuple()
Student = namedtuple('Student', ['name', 'age', 'DOB'])

# Adding values
S = Student('Nandini', '19', '2541997')

# Access using index
print("The Student age using index is : ", end="")
print(S[1])

# Access using name
print("The Student name using keyname is : ", end="")
print(S.name)

Output

The Student age using index is : 19
The Student name using keyname is : Nandini

Operations enabled NamedTuple

Below are the following operations that can done by using namedtuple():

Create a NameTuple
Access Operations
Conversion Operations
Additional Operations

Create a NameTuple in Python

This creates a new namedtuple class using the namedtuple() function/method from the collections module. The first argument is the name of the new class, and the second argument is a list of field names.

Python

from collections import namedtuple

Point = namedtuple('Point', ['x', 'y'])
p = Point(x=1, y=2)
print(p.x, p.y)

Output

1 2

Access Operations

Namedtuples in Python provide convenient ways to access their fields. Below are some access operations provided in Python for NamedTuple:

Access by index
Access by keyname
Access Using getattr()

Access By Index

The property values of namedtuple() are ordered and can be accessed using the index number unlike dictionaries which are not accessible by index. In this example, we are accessing the student’s by using index.

Python

# importing "collections" for namedtuple()
import collections

# Declaring namedtuple()
Student = collections.namedtuple('Student', ['name', 'age', 'DOB'])

# Adding values
S = Student('Nandini', '19', '2541997')

# Access using index
print("The Student age using index is : ", end="")
print(S[1])

Output

The Student age using index is : 19

Access by keyname

Access by keyname is also allowed when in dictionaries. In this example, we are using keyname to access the student’s name.

Python

# importing "collections" for namedtuple()
import collections

# Declaring namedtuple()
Student = collections.namedtuple('Student', ['name', 'age', 'DOB'])

# Adding values
S = Student('Nandini', '19', '2541997')

# Access using name
print("The Student name using keyname is : ", end="")
print(S.name)

Output

The Student name using keyname is : Nandini

Access Using getattr()

This is yet another way to access the value by giving namedtuple and key value when its argument. In this example, we are using getattr() to access the student’s id in the given namedtuple.

Python

# importing "collections" for namedtuple()
import collections

# Declaring namedtuple()
Student = collections.namedtuple('Student', ['name', 'age', 'DOB'])

# Adding values
S = Student('Nandini', '19', '2541997')

# Access using getattr()
print("The Student DOB using getattr() is : ", end="")
print(getattr(S, 'DOB'))

Output

The Student DOB using getattr() is : 2541997

Conversion Operations

Namedtuples provide a few useful conversion operations to work with other data types in Python. Below are the following conversion operations that is provided for namedtuples in Python:

Using _make()
Using _asdict()
Using **(double star) operator

Conversion Using _make()

This function/method is have used to return a namedtuple() from the iterable passed when argument. In this example, we are using _make() to convert the list “li” into namedtuple.

Python

# importing "collections" for namedtuple()
import collections

# Declaring namedtuple()
Student = collections.namedtuple('Student',
                                 ['name', 'age', 'DOB'])

# Adding values
S = Student('Nandini', '19', '2541997')

# initializing iterable
li = ['Manjeet', '19', '411997']

di = {'name': "Nikhil", 'age': 19, 'DOB': '1391997'}

# using _make() to return namedtuple()
print("The namedtuple instance using iterable is  : ")
print(Student._make(li))

Output

The namedtuple instance using iterable is  : 
Student(name='Manjeet', age='19', DOB='411997')

Conversion Operation Using _asdict()

This function/method returns the OrderedDict() when constructed from the mapped values of namedtuple(). In this example, we are using _asdict() to convert the input list into namedtuple instance.

Python

import collections
# Declaring namedtuple()
Student = collections.namedtuple('Student',
                                 ['name', 'age', 'DOB'])

# Adding values
S = Student('Nandini', '19', '2541997')

# initializing iterable
li = ['Manjeet', '19', '411997']

# initializing dict
di = {'name': "Nikhil", 'age': 19, 'DOB': '1391997'}

# using _asdict() to return an OrderedDict()
print("The OrderedDict instance using namedtuple is  : ")
print(S._asdict())

Output

The OrderedDict instance using namedtuple is : 
OrderedDict([('name', 'Nandini'), ('age', '19'), ('DOB', '2541997')])

Using “” (double star) operator**

This function/method is have used to convert a dictionary into the namedtuple(). In this example, we are using “**” to convert the input list into namedtuple.

Python

import collections

# Declaring namedtuple()
Student = collections.namedtuple('Student',
                                 ['name', 'age', 'DOB'])

# Adding values
S = Student('Nandini', '19', '2541997')

# initializing iterable
li = ['Manjeet', '19', '411997']

# initializing dict
di = {'name': "Nikhil", 'age': 19, 'DOB': '1391997'}

# using ** operator to return namedtuple from dictionary
print("The namedtuple instance from dict is  : ")
print(Student(**di))

Output

The namedtuple instance from dict is  : 
Student(name='Nikhil', age=19, DOB='1391997')

Additional Operations

There are some additional operations that are provided in Python for NamedTuples:

_fields
_replace()
__new__()
__getnewargs__()

_fields

This data property is have used to get all the keynames of the namespace declared. In this example, we are using _fields to get all the keynames of the namespace declared.

Python

import collections
Student = collections.namedtuple('Student', ['name', 'age', 'DOB'])

# Adding values
S = Student('Nandini', '19', '2541997')

# using _fields to display all the keynames of namedtuple()
print("All the fields of students are : ")
print(S._fields)

Output

All the fields of students are: 
('name', 'age', 'DOB')

_replace()

_replace() is simillar as str.replace() but targets named fields( does not modify the original values). In this example, we are using _replace() to replace a name from “Nandini” to “Manjeet”.

Python

import collections

# Declaring namedtuple()
Student = collections.namedtuple('Student', 
                           ['name', 'age', 'DOB'])

# Adding values
S = Student('Nandini', '19', '2541997')

# ._replace returns a new namedtuple, 
# it does not modify the original
print("returns a new namedtuple : ")
print(S._replace(name='Manjeet'))

Output

returns a new namedtuple : 
Student(name='Manjeet', age='19', DOB='2541997')

new()

This function/method returns a new instance of the Student class, by taking the values that we may be interested to assign to the keys in the named tuple. In this example, we are using __new__() to return a new instance of the Student class.

Python

import collections

# Declaring namedtuple()
Student = collections.namedtuple('Student', ['name', 'age', 'DOB'])

# Adding values
S = Student('Nandini', '19', '2541997')

# Student.__new__ returns a new instance of Student(name,age,DOB)
print(Student.__new__(Student,'Himesh','19','26082003'))

Output

Student(name='Himesh', age='19', DOB='26082003')

getnewargs()

This function/method returns the named tuple when a plain tuple. In this example, we are doing the same by using __getnewargs__().

Python

import collections

# Declaring namedtuple()
Student = collections.namedtuple('Student', ['name', 'age', 'DOB'])

# Adding values
S = Student('Nandini', '19', '2541997')

H=Student('Himesh','19','26082003')
# .__getnewargs__ returns the named tuple when a plain tuple
print(H.__getnewargs__())

Output

('Himesh', '19', '26082003')