NamedTuple in Python - Part 1

In this post, we will understand what a NamedTuple in Python is, how it is different from other container structures and how it can be created.

Note: Remember that NamedTuple was introduced in Python 2.6 and can be used in the versions >=2.6 only.

What is a NamedTuple?

You might be familiar with a tuple, it is an immutable data structure that is used to store data elements in Python. As the name suggests, the NamedTuple is a tuple in which every value has a pre-assigned name associated with it. It is present in the collections module. It is a container and is similar to dictionaries because it contains a key that is associated with a specific data element/value (multiple values also can be mapped).

One significant difference between a NamedTuple and a dictionary is that NamedTuple can be accessed with the help of a key as well as iterating over the elements in the NamedTuple. This functionality hasn't been implemented in dictionaries as of now.

How to define a NamedTuple?

There are different ways to define a NamedTuple, few of them have been listed below:

1. As a string which is comma-separated

Since a key-value pair (similar to a dictionary) only can be passed to a NamedTuple, if the number of values associated with a specific namedtuple is more than one, it has to be passed as a string or in such a way with which it is interpreted as a single entity mapped to the key.

As shown in the image above, Website_details is the name of the namedtuple and that named tuple can store two values for the key, Name and Type.

Time for an example:

from collections import namedtuple

# initialising a named tuple
website = namedtuple('Website_details', "Name, Type")
# adding values to it
my_website = website('Studytonight', 'Student friendly')
print(my_website)

Output:

Website_details(Name='Studytonight', Type='Student friendly')

2. Using a list for keys

The value associated with the namedtuple can be passed as a list as well, when the number of keys associated with a namedtuple is greater than 1 (usually, this is the case, otherwise, dictionaries could be used).

Time for an example:

from collections import namedtuple

website = namedtuple('Website_details', ['Name', 'Type', 'number_of_characters'])
my_website = website( 'Studytonight', 'Student friendly', 12)
print(my_website)

Output:

Website_details(Name='Studytonight', Type='Student friendly', number_of_characters=12)

3. Passing Keys as a string which is space-separated

The key bound with a namedtuple can also be passed as a string that is separated by spaces.

Time for an example:

from collections import namedtuple

website = namedtuple('Website_details', 'Name Type number_of_characters')
my_website = website( 'Studytonight', 'Student friendly', 12)
print(my_website)

Output:

Website_details(Name='Studytonight', Type='Student friendly', number_of_characters=12)

4. Using a dictionary

The keys associated with a namedtuple can be passed as dictionary elements which can later be mapped to values.

Time for an example:

from collections import namedtuple

website = namedtuple('Website_details', {'Name':'', 'Type':'', 'number_of_characters':''})
my_website = website( 'Studytonight', 'Student friendly', 12)
print(my_website)

Output:

Website_details(Name='Studytonight', Type='Student friendly', number_of_characters=12)

Conclusion:

In this post, we saw what a NamedTuple is, and how it is different from a dictionary. We also saw how a NamedTuple can be defined in different ways. In the next tutorial covering NamedTuple we will cover some useful methods associated with namedtuple.