Python Condition Statement with For-Loop

I am attempting to write a single line of Python code for the following:

is_valid = False
for single_object in object_list:
  if single_object.test == test:
    is_valid = True

if not is_valid:
  return 'Bad data!'

I know that there has to be a way to accomplish this 开发者_StackOverflowin less code. I mean, it's Python!

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is_valid = any(o.test == test for o in object_list)

The any(iterable) function returns True if any of the values in iterable are True, and False if none of them are. I'm using a "generator expression" to go through the values in object_list and evaluate the condition.

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Less code is often not better code.

for single_object in object_list:
    if single_object.test == test:
        break
else:
    return 'Bad data!'

While this is not one line of code, it is less, cleaner code, and is arguably easier to read than any. It's also basically the same speed.

The else clause on a loop only executes if the loop wasn't exited by a break statement.

I think this is just as Pythonic as the one line solution.

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@Jeremy Banks's solution seems to be perfect to me. Nevertheless I would like to present another one. Not in order to be even superior (it is not), but to show alternatives for non-boolean problems, or if it is important to get the very precise object in the list (maybe in order to modify or remove it).

valid_one = next((o.test for o in object_list if o.test == test), None)
if valid_one is None:
    # not valid
else:
    object_list.remove(valid_one)
    # or
    valid_one.special_atr = 42