TypeError: Reduce() of empty sequence with no initial value
Nobody answer why there is an error:TypeError: reduce() of empty sequence with no initial value
When the list literal which is second parameter is empty, the error occurs. So if you tryreduce(lambda x, y:(x[0]+y[0], x[1]+y[1]), [])
You'll get the error.
map(sum, ...) fits better, looks beautiful.
map(sum, zip(*mapped))You can use itertools.izip_longest if lengths of the lists are different.
Use this way:
>>> reduce(lambda x,y:(x[0]+y[0], x[1]+y[1]),[i for i in mapped])(3, 119)>>> reduce(lambda x,y:(x[0]+y[0], x[1]+y[1]),(i for i in mapped))(3, 119)What you miss is that lambda should take two parameters, you just give one.
For Python3.x see the code below:
>>> from functools import reduce>>> reduce(lambda x:(x[0]+y[0], x[1]+y[1]),(i for i in mapped))Traceback (most recent call last): File "<stdin>", line 1, in <module>TypeError: <lambda>() takes exactly 1 positional argument (2 given)>>> reduce(lambda x,y:(x[0]+y[0], x[1]+y[1]),(i for i in mapped))(3, 119)