Newbie Q on searching lists

[Wojtek Walczak]

Dnia Sat, 23 Nov 2002 05:45:55 GMT, Kenny Tilton napisał(a):
> I see the index method on lists throws an error if the element sought is 
> not found. I was hoping it would return None.
Yes, you're right, but it's easy to walk around:

def ind(list, arg):
    if arg in list:
       return list.index(arg)
    else:
       return 'None'

aList = [1, 'a', 2, 'b']

ind(a,'b') => 3
ind(a,7)   => 'None'

or even in one liner:

((c in a and (a.index(c),)) or ('None',))[0]

for example:

[((c in a and (a.index(c),)) or ('None',))[0] for c in ['b',6]]

returns: [3, 'None']

HTH.

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