5 Best Ways to Find Whether All Tuples Have the Same Length in Python

by

💡 Problem Formulation: When working with tuples in Python, a common situation might involve ensuring that all tuples in a given collection, such as a list, have the same length. For example, given the input [ (1, 2), (3, 4), (5, 6) ], the desired output would be True since all tuples have the same length of 2. However, for [ (1, 2, 3), (3, 4), (5, 6) ], the desired output would be False.

Method 1: Using a for loop to check tuple lengths

This method iterates over each tuple in the collection using a for loop. It compares the length of each tuple to the length of the first one. If any tuple does not match, it returns False, otherwise it returns True after completing the iteration.

♥️ Info: Are you AI curious but you still have to create real impactful projects? Join our official AI builder club on Skool (only $5): SHIP! - One Project Per Month

Here’s an example:

def all_tuples_same_length(tuples):
    first_length = len(tuples[0])
    for t in tuples[1:]:
        if len(t) != first_length:
            return False
    return True

tuples_list = [(1, 2), (3, 4), (5, 6)]
print(all_tuples_same_length(tuples_list))

The output of this code snippet is:

True

This code snippet defines a function all_tuples_same_length that takes a list of tuples tuples_list and compares the length of each tuple to the first one. It uses a for loop to iterate through the list. The function returns True if all the tuples have the same length; otherwise, it returns False.

Method 2: Using the built-in all() function

The all() function in Python returns True if all elements of the iterable are true. This method combines all() with a generator expression that checks the length of the tuples against the first tuple’s length in the iterable.

Here’s an example:

tuples_list = [(1, 2), (3, 4), (5, 6)]
first_length = len(tuples_list[0])
print(all(len(t) == first_length for t in tuples_list))

The output of this code snippet is:

True

The code uses all() with a generator expression that iterates through each tuple in tuples_list, checking whether their lengths match the length of the first tuple. The expression len(t) == first_length evaluates to either True or False for each tuple, and all() returns True only if all expressions are True.

Method 3: Using map() and set()

This method uses the map() function to apply the len() function to every tuple in the collection, and then converts the resulting lengths to a set to determine the number of unique lengths. If the set has only one unique length, it implies all tuples have the same length.

Here’s an example:

tuples_list = [(1, 2), (3, 4), (5, 6)]
lengths = set(map(len, tuples_list))
print(len(lengths) == 1)

The output of this code snippet is:

True

The map(len, tuples_list) function call applies the len function to every element in tuples_list, generating a list of lengths. This list is passed to the set() constructor, which eliminates any duplicates, leaving us with a set of unique lengths. The code finally checks if the set has exactly one element, which confirms that all tuple lengths are the same.

Method 4: Using itertools.starmap()

Similar to Method 3, this one uses the itertools.starmap() function to apply len() to each tuple. The approach of checking for a single unique length in the set to ensure all tuples are of the same length is the same.

Here’s an example:

import itertools

tuples_list = [(1, 2), (3, 4), (5, 6)]
lengths = set(itertools.starmap(len, tuples_list))
print(len(lengths) == 1)

The output of this code snippet is:

True

In this example, the itertools.starmap() function is used to create an iterator that applies the len function to each tuple in tuples_list. As with the previous method, a set is created from the map object, and its length is checked to determine if all tuples are of the same length.

Bonus One-Liner Method 5: Using a list comprehension

For a short and concise solution, this one-liner uses a list comprehension inside the all() function to check the tuple lengths.

Here’s an example:

tuples_list = [(1, 2), (3, 4), (5, 6)]
print(all(len(t) == len(tuples_list[0]) for t in tuples_list))

The output of this code snippet is:

True

This example makes use of Python’s ability to generate compact and readable code. It’s essentially a more concise version of Method 2, using a list comprehension to check if all tuples in tuples_list have the same length as the first tuple.

Summary/Discussion

  • Method 1: For Loop. Straightforward. May not be the most Pythonic way and could be considered verbose for this type of problem.
  • Method 2: all() with Generator Expression. Elegant and Pythonic. Requires understanding of generator expressions and the all() function.
  • Method 3: Using map() and set(). Efficient and quick. Requires additional memory for set creation, and slight indirectness in logic.
  • Method 4: Using itertools.starmap(). Clean and effective. Similar to Method 3 but makes use of the itertools module, which might be overkill for such a simple task.
  • Method 5: One-Liner List Comprehension. Most concise. Great for short scripts or inline use, but may impact readability for those new to Python.