On 6/6/2011 12:52 PM, Terry Reedy wrote:
def group(seq, n):
'Yield from seq successive disjoint slices of length n & the remainder'
if n<=0: raise ValueError('group size must be positive')
for i in range(0,len(seq), n):
yield seq[i:i+n]
for inn,out in (
(('',1), []), # no input, no output
#(('abc',0), ValueError), # group size positive
(('abc',1), ['a','b','c']),
(('abcd',2), ['ab','cd']),
(('abcde',2), ['ab', 'cd', 'e']), # could change this
):
assert list(group(*inn)) == out, (inn,out)
I forgot to mention that any function that takes a 'sequence' as input
should be tested with both strings and non-strings. I learned this when
a function tested with one failed mysteriously with the other. Strings
are unique in that indexing returns a slice (and hence a string) rather
than a separate class of item. It this case, there is no indexing and no
use of class to create new items. However, adding a couple of lines like
(((),1), []),
(((1,2,3,4),2), [(1,2), (3,4)]),
to the test sequence checks the current code and guards against future
changes.
--
Terry Jan Reedy
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