Default return values for out-of-bounds list item
steve at REMOVE-THIS-cybersource.com.au
Fri Jan 22 03:28:23 CET 2010
On Thu, 21 Jan 2010 17:56:00 -0800, gburdell1 at gmail.com wrote:
> Is there a built-in method in python that lets you specify a "default"
> value that will be returned whenever you try to access a list item that
> is out of bounds?
> Basically, it would be a function like this:
> def item(x,index,default):
> return x[index]
> except IndexError:
> return default
That's probably the best way to do it.
> So if a=[0,1,2,3], then item(a,0,44)=0, item(a,1,44)=1, and item(a,
> 1000,44)=44, item(a,-1000,44)=44
> What I want to know is whether there is a built-in method or notation
> for this. What if, for example, we could do something like a [1000,44] ?
You can use slicing instead:
and then detect the empty list and use default:
def item(x, index, default):
a = x[index:index+1]
return a if a else default
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