Summing each array inside list-CodePudding

I have a list of arrays generated from another function:

testGroup = [array([18]), array([], dtype=int64), array([56, 75, 55, 55]), array([32])]

I'd like to return the sum of each individual array in the list, with the empty ones returning as zero

I've tried using numpy, as per the documentation:

np.sum([[0, 1], [0, 5]], axis=1)
array([1, 5])np.sum([[0, 1], [0, 5]], axis=1)
array([1, 5])

But when I try np.sum(testGroup, axis=1) I get an axis error as I suppose the empty arrays have a dimension less than one?

I've also tried summing it directly arraySum = sum(testGroup) but get a ValueError

Any ideas on how to achieve a sum of the arrays inside the testGroup list?

CodePudding user response：

testGroup is a plain python list, that happens to contain numpy.array elements. Instead you can use a list comprehension

>>> [np.sum(a) for a in testGroup]
[18, 0, 241, 32]

CodePudding user response：

Try list(map(np.sum, testGroup)) it gives

[18, 0, 241, 32]

CodePudding user response：

You might use so-called list-comprehension to apply function to each element of list as follow

import numpy as np
testGroup = [np.array([18]), np.array([], dtype=np.int64), np.array([56, 75, 55, 55]), np.array([32])]
totals = [np.sum(i) for i in testGroup]
print(totals)

output

[18, 0, 241, 32]