Hi,
say we have the following:
>>> data = [('foo', 1), ('foo', 2), ('bar', 3), ('bar', 2)]
is there a way to code a function iter_in_blocks such that
>>> result = [ list(block) for block in iter_in_blocks(data) ]
evaluates to
>>> result = [ [('foo', 1), ('foo', 2)], [('bar', 3), ('bar', 2)] ]
by _only_ _iterating_ over the list (caching all the elements sharing
the same first element doesn't count)?
I came up with the following
def iter_in_blocks(iterable):
my_iter = iter(iterable)
while True:
first = next(my_iter)
pred = lambda entry: entry[0] == first[0]
def block_iter():
yield first
for entry in itertools.takewhile(pred, my_iter):
yield entry
yield block_iter()
which does not work as itertools.takewhile consumes the first entry
not fulfilling the pred.
I currently have the intuition that the problem is not solvable
without using e.g. a global to pass something back to iter_in_blocks
from block_iter. Any other suggestions?
Regards,
Thomas Bach.
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