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I have a Python array, like so:
[[1,2,3],
[1,2,3]]
I can add the row by doing sum(array[i]), how can I sum a column, using a double for loop?
I.E. for the first column, I could get 2, then 4, then 6.
948
We can find sum of each column of the given nested list using zip function of python enclosing it within list comprehension. Another approach is to use map(). We apply the sum function to each element in a column and find sum of each column accordingly.
sum() function in Python Sum of numbers in the list is required everywhere. Python provides an inbuilt function sum() which sums up the numbers in the list. Syntax: sum(iterable, start) iterable : iterable can be anything list , tuples or dictionaries , but most importantly it should be numbers.
Using a for loop (in a generator expression):
data = [[1,2,3],
[1,2,3]]
column = 1
print(sum(row[column] for row in data)) # -> 4
Try this:
a = [[1,2,3],
[1,2,3]]
print [sum(x) for x in zip(*a)]
zip function description
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