How to handle exceptions in a list comprehensions?

Nathan_Fellman_1084 0
Viewed 89268

I have some a list comprehension in Python in which each iteration can throw an exception.

For instance, if I have:

eggs = (1,3,0,3,2)

[1/egg for egg in eggs]

I'll get a ZeroDivisionError exception in the 3rd element.

How can I handle this exception and continue execution of the list comprehension?

The only way I can think of is to use a helper function:

def spam(egg):
    try:
        return 1/egg
    except ZeroDivisionError:
        # handle division by zero error
        # leave empty for now
        pass

But this looks a bit cumbersome to me.

Is there a better way to do this in Python?

Note: This is a simple example (see "for instance" above) that I contrived because my real example requires some context. I'm not interested in avoiding divide by zero errors but in handling exceptions in a list comprehension.

list-comprehension exception python
7 Answers

I didn't see any answer mention this. But this example would be one way of preventing an exception from being raised for known failing cases.

eggs = (1,3,0,3,2)
[1/egg if egg > 0 else None for egg in eggs]


Output: [1, 0, None, 0, 0]
user_51040860

You can use generators:

def invert(xs):
    for x in xs:
        try:
            yield x
        except:
            yield None

list(invert(eggs))
user_7248730
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