Summing list of counters in python
The sum
function has the optional start argument which defaults to 0. Quoting the linked page:
sum(iterable[, start])
Sums start and the items of an iterable from left to right and returns the total
Set start to (empty) Counter
object to avoid the TypeError
:
In [5]: sum(counter_list, Counter())
Out[5]: Counter({'b': 5, 'c': 4, 'a': 1})