itertools.groupby
Steven D'Aprano
steve+comp.lang.python at pearwood.info
Sat Apr 20 20:13:27 EDT 2013
On Sat, 20 Apr 2013 11:09:42 -0600, Jason Friedman wrote:
> I have a file such as:
>
> $ cat my_data
> Starting a new group
> a
> b
> c
> Starting a new group
> 1
> 2
> 3
> 4
> Starting a new group
> X
> Y
> Z
> Starting a new group
>
> I am wanting a list of lists:
> ['a', 'b', 'c']
> ['1', '2', '3', '4']
> ['X', 'Y', 'Z']
> []
>
> I wrote this:
[...]
> I get the output I desire, but I'm wondering if there is a solution
> without the global counter.
I wouldn't use groupby. It's a hammer, not every grouping job is a nail.
Instead, use a simple accumulator:
def group(lines):
accum = []
for line in lines:
line = line.strip()
if line == 'Starting a new group':
if accum: # Don't bother if there are no accumulated lines.
yield accum
accum = []
else:
accum.append(line)
# Don't forget the last group of lines.
if accum: yield accum
--
Steven
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