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Python any(): Check if at least one element is truthy

The built-in any() function returns True if at least one element in an iterable is truthy; otherwise it returns False. It evaluates lazily and short-circuits on the first truthy value, which makes it efficient for large datasets and streaming sources.

Syntax

any(iterable)

Parameter: Any iterable (list, tuple, set, dict, generator, iterator, etc.).

Returns: True if one or more elements are truthy; False if none are truthy or the iterable is empty. Note that any([]) returns False by definition.

Truthiness rules

• Falsy: False, None, numeric zero (0, 0.0), empty containers ([], (), {}, set(), ""), and objects whose __bool__() returns False or __len__() returns 0.
• Truthy: Everything else, including non-zero numbers, non-empty strings, and non-empty containers.

Quick examples

print(any([0, "", None]))         # False (all falsy)
print(any([0, "", 5]))            # True  (5 is truthy)
print(any([]))                    # False (empty iterable)
print(any(x > 10 for x in [3, 12, 7]))  # True (12 > 10)

Short-circuiting and generators

any() consumes iterables lazily. With generators or comprehensions, evaluation stops at the first truthy element, saving time and memory.

def has_missing(values):
    # True if any value is None or empty string
    return any(v is None or v == "" for v in values)

row = ["id42", "Alice", "", "NY"]
print(has_missing(row))  # True (stops when "" is found)

Common use cases

• Validation: Detect presence of errors or flags in a record.
• Threshold checks: Determine if any measurements exceed a limit.
• Feature existence: Confirm at least one optional field is filled.

temperatures = [18, 21, 33, 25]
print(any(t > 30 for t in temperatures))  # True

Pitfalls and caveats

• Dicts iterate keys: any({0: False, 1: False}) checks keys (0, 1), not values. Use any(d.values()) to test values.
• Empty iterable is False: If you need to ensure non-empty and at least one truthy element, combine checks appropriately.
• Whitespace strings: Non-empty strings like " " are truthy; trim or validate content explicitly.

d = {"a": False, "b": True}
print(any(d))           # True (keys "a", "b" are truthy)
print(any(d.values()))  # True (checks actual boolean values)

Performance notes

• Laziness: Stops early on the first truthy element, avoiding full traversal.
• Memory efficiency: Prefer generators (e.g., (pred(x) for x in data)) over lists to avoid temporary allocations.
• Expensive predicates: Cache or pre-filter to maximize benefits of short-circuiting.

Comparison with all()

• any(): True if at least one element is truthy; empty iterable yields False.
• all(): True only if every element is truthy; empty iterable yields True.

vals = [0, "", None, 5]
print(any(vals))  # True  (5 is truthy)
print(all(vals))  # False (0, "", None are falsy)

FAQ

Does any() work with custom objects?

Yes. Truthiness is determined by __bool__() or, if absent, by __len__() being non-zero.

How do I require non-empty and at least one truthy element?

Combine checks: iterable and any(iterable) or len(iterable) > 0 and any(predicate(x) for x in iterable).

Can I detect which element caused any() to return True?

any() does not return the element. Iterate manually or use next() with a generator to retrieve it.

Related keywords

Python any, truthiness, short-circuit evaluation, generators, validation, iterable, any vs all, boolean context, performance

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