Using enumerate to get line-numbers with itertools grouper?
Victor Hooi
victorhooi at gmail.com
Wed Sep 2 06:04:36 EDT 2015
I'm using grouper() to iterate over a textfile in groups of lines:
def grouper(iterable, n, fillvalue=None):
"Collect data into fixed-length chunks or blocks"
# grouper('ABCDEFG', 3, 'x') --> ABC DEF Gxx
args = [iter(iterable)] * n
return zip_longest(fillvalue=fillvalue, *args)
However, I'd also like to know the line-number that I'm up to, for printing out in informational or error messages.
Is there a way to use enumerate with grouper to achieve this?
The below won't work, as enumerate will give me the index of the group, rather than of the lines themselves:
_BATCH_SIZE = 50
with open(args.input_file, 'r') as f:
for line_number, chunk in enumerate(grouper(f, _BATCH_SIZE)):
print(line_number)
I'm thinking I could do something to modify grouper, maybe, but I'm sure there's an easier way?
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