[Numpy-discussion] preferred way of testing empty arrays

Chris Barker chris.barker@noaa....
Mon Jan 30 18:35:05 CST 2012


On Fri, Jan 27, 2012 at 1:29 PM, Robert Kern <robert.kern@gmail.com> wrote:
> Well, if you really need to do this in more than one place, define a
> utility function and call it a day.
>
> def should_not_plot(x):
>    if x is None:
>        return True
>    elif isinstance(x, np.ndarray):
>        return x.size == 0
>    else:
>        return bool(x)

I tend to do things like:

def convert_to_plotable(x):
    if x is None:
        return None
    else:
        x = np.asarray(x)
        if b.size == 0:
            return None
    return x

it does mean you need to check for None later anyway, but I like to
convert to an array early in the process -- then you know you have
either an array or None at that point.

NOTE: you could also raise and handle an exception instead.

-Chris
-- 

Christopher Barker, Ph.D.
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