41. Named Tuples

Here are 10 Python snippets demonstrating how to work with Named Tuples using collections.namedtuple:

1. Creating a Basic Named Tuple

This creates a simple named tuple to represent a point in 2D space.

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from collections import namedtuple

Point = namedtuple('Point', ['x', 'y'])
point = Point(3, 4)
print(point.x, point.y)  # Output: 3 4

Here, Point is a named tuple with fields x and y.

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2. Accessing Fields by Name

You can access the fields of a named tuple by name rather than by index.

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from collections import namedtuple

Person = namedtuple('Person', ['name', 'age'])
person = Person(name='Alice', age=30)

print(person.name)  # Output: Alice
print(person.age)   # Output: 30

This demonstrates how to access named fields instead of using numerical indices.

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3. Default Values in Named Tuples

Named tuples can be extended to allow default values by using defaults.

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from collections import namedtuple

Person = namedtuple('Person', ['name', 'age', 'location'])
Person.__new__ = lambda cls, name, age, location='Unknown': super().__new__(cls, (name, age, location))

person = Person('Bob', 25)
print(person.name, person.age, person.location)  # Output: Bob 25 Unknown

This sets a default for the location field.

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4. Using _replace to Modify Named Tuples

Since named tuples are immutable, you can use the _replace method to create a modified copy.

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from collections import namedtuple

Car = namedtuple('Car', ['make', 'model', 'year'])
car = Car('Toyota', 'Camry', 2020)

# Replace the 'year' field
updated_car = car._replace(year=2021)
print(updated_car)  # Output: Car(make='Toyota', model='Camry', year=2021)

This creates a new instance with the modified value for year.

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5. Named Tuples with Additional Methods

Named tuples can be subclassed to add custom methods.

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from collections import namedtuple

Car = namedtuple('Car', ['make', 'model', 'year'])

class CarWithMethod(Car):
    def description(self):
        return f"{self.make} {self.model} ({self.year})"

car = CarWithMethod('Honda', 'Civic', 2020)
print(car.description())  # Output: Honda Civic (2020)

Here, we added a description() method to the Car named tuple.

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6. Unpacking Named Tuples

Named tuples support unpacking, just like regular tuples.

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from collections import namedtuple

Rectangle = namedtuple('Rectangle', ['width', 'height'])
rect = Rectangle(10, 20)

# Unpacking
width, height = rect
print(width, height)  # Output: 10 20

This shows how to unpack the fields of a named tuple into variables.

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7. Named Tuples as Dictionary Keys

Named tuples are hashable and can be used as keys in dictionaries.

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from collections import namedtuple

Point = namedtuple('Point', ['x', 'y'])
points_dict = {}
point = Point(1, 2)

# Using named tuple as a dictionary key
points_dict[point] = "Origin"
print(points_dict)  # Output: {Point(x=1, y=2): 'Origin'}

This demonstrates using a named tuple as a dictionary key.

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8. Iterating Over Named Tuples

You can iterate over the fields of a named tuple just like a regular tuple.

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from collections import namedtuple

Person = namedtuple('Person', ['name', 'age', 'location'])
person = Person('Charlie', 35, 'New York')

for field in person:
    print(field)

This will output each field of the person named tuple in sequence.

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9. Named Tuples with OrderedDict

You can convert a named tuple to an OrderedDict for better flexibility in field names.

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from collections import namedtuple, OrderedDict

Person = namedtuple('Person', ['name', 'age'])
person = Person('David', 40)

# Convert to OrderedDict
person_dict = OrderedDict(person._asdict())
print(person_dict)  # Output: OrderedDict([('name', 'David'), ('age', 40)])

This converts the named tuple to an ordered dictionary.

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10. Named Tuple with Length and Count

You can use the len() and count() methods with named tuples.

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from collections import namedtuple

Student = namedtuple('Student', ['name', 'age', 'grade'])
student = Student('Eva', 22, 'A')

# Length of named tuple
print(len(student))  # Output: 3

# Count occurrences of a field value
print(student.count('A'))  # Output: 1

This demonstrates using the len() function and count() with a named tuple.

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These snippets cover a variety of ways to use Named Tuples in Python, demonstrating how they provide an easy-to-use, readable, and immutable alternative to regular tuples. Named tuples can be very handy for data structures and organizing information efficiently.