Mike C. Fletcher wrote:
Alan McIntyre wrote:
...
I have a list of items that has contiguous repetitions of values, but
the number and location of the repetitions is not important, so I just
need to strip them out. For example, if my original list is
[0,0,1,1,1,2,2,3,3,3,2,2,2,4,4,4,5], I want to end up with
[0,1,2,3,2,4,5].
...
Is there an elegant way to do this, or should I just stick with the
code above?
>>> def changes( dataset ):
... last = None
... for value in dataset:
... if value != last:
... yield value
... last = value
... >>> print list(changes(data ))
which is quite readable/elegant IMO.
But fails if the list starts with None:
py> lst = [None,0,0,1,1,1,2,2,3,3,3,2,2,2,4,4,4,5]
py> def changes(dataset):
... last = None
... for value in dataset:
... if value != last:
... yield value
... last = value
...
py> list(changes(lst))
[0, 1, 2, 3, 2, 4, 5]
A minor modification that does appear to work:
py> def changes(dataset):
... last = object()
... for value in dataset:
... if value != last:
... yield value
... last = value
...
py> list(changes(lst))
[None, 0, 1, 2, 3, 2, 4, 5]
STeVe
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