5 Best Ways to Create a List of Tuples from a Given List Having Number and Its Cube in Each Tuple Using Python

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πŸ’‘ Problem Formulation: Python developers are often tasked with transforming a list of numbers into a list of tuples, where each tuple consists of a number from the list and its corresponding cube. For example, given the list [1, 2, 3], the desired output would be [(1, 1), (2, 8), (3, 27)].

Method 1: Using a For Loop

One basic approach to creating a list of tuples with numbers and their cubes is to iterate over the list using a for loop. In each iteration, append a tuple to the result list, which contains the current number and its cube calculated with the exponent operator.

Here’s an example:

numbers = [1, 2, 3, 4, 5]
tuples_list = []
for number in numbers:
    tuples_list.append((number, number**3))

Output: [(1, 1), (2, 8), (3, 27), (4, 64), (5, 125)]

This method directly iterates over the numbers and appends each calculated tuple to a new list. It’s simple and easy to understand, making it perfect for beginners.

Method 2: Using List Comprehension

List comprehension is a concise way to create lists in Python. It can be used to generate a list of tuples where each tuple is formed from a number and its cube by iterating over the original list in a single line of code.

Here’s an example:

tuples_list = [(number, number**3) for number in [1, 2, 3, 4, 5]]

Output: [(1, 1), (2, 8), (3, 27), (4, 64), (5, 125)]

This elegant one-liner leverages comprehension to build the entire list in a compact form, greatly reducing the number of lines needed and enhancing readability.

Method 3: Using the map() Function

The map() function is a powerful tool in Python that applies a given function to all items in an iterable. A lambda function can be used here to produce tuples that include both a number and its cube.

Here’s an example:

numbers = [1, 2, 3, 4, 5]
tuples_list = list(map(lambda number: (number, number**3), numbers))

Output: [(1, 1), (2, 8), (3, 27), (4, 64), (5, 125)]

This method uses a functional programming style to transform the list. The lambda function is concise but may be less readable to those unfamiliar with functional or Python’s lambda syntax.

Method 4: Using a Generator Expression

A generator expression is similar to list comprehension but is more memory efficient as it yields items one by one using an iterator, rather than creating the entire list at once. Wrapped in a call to list(), it can create the desired list of tuples.

Here’s an example:

tuples_list = list((number, number**3) for number in [1, 2, 3, 4, 5])

Output: [(1, 1), (2, 8), (3, 27), (4, 64), (5, 125)]

This approach is suitable for large datasets as it does not hold all tuples in memory at once, generating them on-the-fly instead.

Bonus One-Liner Method 5: Using the zip() Function

The zip() function can be used cleverly to create a list of tuples. By zipping the original list with a list of cubes, each created by list comprehension, we achieve the desired outcome efficiently.

Here’s an example:

numbers = [1, 2, 3, 4, 5]
tuples_list = list(zip(numbers, [number**3 for number in numbers]))

Output: [(1, 1), (2, 8), (3, 27), (4, 64), (5, 125)]

This one-liner is concise and leverages the built-in zip() function to combine two lists into one list of tuples. It is both readable and efficient.

Summary/Discussion

  • Method 1: For Loop. Simple and straightforward. May be seen as verbose compared to other methods.
  • Method 2: List Comprehension. Very concise and readable. Preferred for its elegance and simplicity.
  • Method 3: map() Function. Functional programming style. Might be less intuitive for some users.
  • Method 4: Generator Expression. Memory efficient for large lists. Slightly less direct than list comprehension.
  • Method 5: zip() Function. Creative use of zip to pair elements. Combines readability with compact code.