checking if a list is empty

[Jon Clements]

On May 7, 12:51 am, Ian Kelly <ian.g.ke... at gmail.com> wrote:
> On Fri, May 6, 2011 at 4:21 PM, Philip Semanchuk <phi... at semanchuk.com> wrote:
> > What if it's not a list but a tuple or a numpy array? Often I just want to iterate through an element's items and I don't care if it's a list, set, etc. For instance, given this function definition --
>
> > def print_items(an_iterable):
> >    if not an_iterable:
> >        print "The iterable is empty"
> >    else:
> >        for item in an_iterable:
> >            print item
>
> > I get the output I want with all of these calls:
> > print_items( list() )
> > print_items( tuple() )
> > print_items( set() )
> > print_items( numpy.array([]) )
>
> But sadly it fails on iterators:
> print_items(xrange(0))
> print_items(-x for x in [])
> print_items({}.iteritems())

My stab:

from itertools import chain

def print_it(iterable):
    it = iter(iterable)
    try:
        head = next(it)
    except StopIteration:
        print 'Empty'
        return
    for el in chain( (head,), it ):
        print el

Not sure if I'm truly happy with that though.

Jon
Jon.