Remove empty tuples from a list - Python

The task of removing empty tuples from a list in Python involves filtering out tuples that contain no elements i.e empty. For example, given a list like [(1, 2), (), (3, 4), (), (5,)], the goal is to remove the empty tuples () and return a new list containing only non-empty tuples: [(1, 2), (3, 4), (5,)].

Using list comprehension

List comprehension is the most efficient way to remove empty tuples from a list. It creates a new list in a single line by filtering out empty tuples, making the code clear, concise, and fast.

a = [(1, 2), (), (3, 4), (), (5,)]
res = [t for t in a if t]
print(res)

[(1, 2), (3, 4), (5,)]

Explanation : list comprehension iterates over each element t in a, adding only non-empty tuples to res by filtering out those that evaluate to False.

Using filter()

filter() is a functional programming approach to remove empty tuples from a list. Using None as the first argument automatically filters out all falsy values, including empty tuples because empty tuples evaluate to False in Python.

a = [(1, 2), (), (3, 4), (), (5,)]
res = list(filter(None, a))
print(res)

[(1, 2), (3, 4), (5,)]

Explanation: list(filter(None, a)) filters out empty tuples from a by retaining only elements that evaluate to True, as empty tuples are False in Python.

Using itertools compress

compress() from the itertools module can remove empty tuples from a list by using a boolean mask. It creates a mask indicating whether each tuple is non-empty, and selects only the non-empty tuples based on the mask.

from itertools import compress
a = [(1, 2), (), (3, 4), (), (5,)]
res = list(compress(a, [bool(t) for t in a]))
print(res)

[(1, 2), (3, 4), (5,)]

Explanation: list(compress(a, [bool(t) for t in a])) uses compress() with a boolean mask to filter out empty tuples from a, returning only non-empty tuples in res.

Using for loop

This basic approach removes empty tuples from a list using a for loop and append(). It checks each tuple and appends only non-empty tuples to a new list, but it’s less efficient compared to modern alternatives like list comprehension.

a = [(1, 2), (), (3, 4), (), (5,)]
res = [] 
for t in a:
    if t:
        res.append(t)
print(res)

[(1, 2), (3, 4), (5,)]

Explanation: for loop iterates over each tuple t in the list a, checks if t is non-empty evaluates to True and appends it to the list res.