Ryan Krauss wrote:

I have a style question. With the old scipy/Numeric, when I had a vector I wanted to be an optional variable in a function I would set is default to "myvect=[]". Then when I wanted to test whether or not the variable had been specified, I just checked "if myvect:". With numpy arrays, this produces a message about ambiguous results for testing arrays and says I should use myvect.any(). The problem is that empty lists don't have an "any" method. I could set the optional arrays explicitly to None or I could check if it" ==[]", but both of these are slightly more fragile (if I accidentally pass an empty list instead of None it would cause problems). I could also set the optional array to "array([])" and always test "any()", but that is more typing.

I typically use None for optional array arguments. But, you could do what your doing and test if any(myvect): <do something> else: <do something else> But, I think the None test is less prone to error. -Travis

Paul Ray wrote:

Assuming you use None for unset optional arguments, how do you do the test?

if myvect is not None: <do something> ?

This is *the* canonical, Pythonic approach. -- Robert Kern robert.kern@gmail.com "In the fields of hell where the grass grows high Are the graves of dreams allowed to die." -- Richard Harter