slicing, mapping types, ellipsis etc.

[Scott David Daniels]

Jerry Sievers wrote:
> I'd like to know;
> 1. what the Ellipsis object or ... syntax is used for
Use the Numeric (or numarray) package to really see these in use.
Otherwise, you mostly get to implement it yourself.

 > 2. what a slice [..., j:k:l] does
Again, see numeric.  Essentially, select parts of a matrix (or higher
dimensional array) based on a stride in the last dimension.

> 3. how slices are applied to object of mapping types
One way to investigate this interactively:

class CheckOut(object):
     def __init__(self, name=None):
	self.name = name or str(self)
     def __getitem__(self, *args, **kwargs):
         print '%s._gi_(*%r, **%r):' % (self.name, args, kwargs),
         return input()

 >>> c = CheckOut('a')
 >>> b = c[1, ...]
c.gi(*(1, Ellipsis), **{}): self.name * 7
 >>> b
'aaaaaaa'

--Scott David Daniels
Scott.Daniels at Acm.Org