How to find the length of array within a tuple

Question

I have a tuple of arrays and need to find the length of an array by using the index of the tuple. This tuple is generated from a sparse matrix alternative to numpy where i'm using scipy.sparse.csr_matrix and numpy.unravel_index based on this post

ie:

>>>T = [(array([0,1,2,3,4,5]),), (array([0,1,2,3,4,5,6,7,8,9]),)]
>>>print(T[1])
(array([0,1,2,3,4,5,6,7,8,9]),)

I need to find the length of each array within the tuple for use later. using len() does not work

>>>len(T[1])
1

I am using this within a for loop that iterates through each array using those arrays as an index for other data.

I have searched and searched for how to solve this but found nothing. Please help!

Of course it won't work because `(array([0,1,2,3,4,5,6,7,8,9]),)` is a tuple that contains one item. Just try to access it: `len(T[1][0])` — mathfux, Feb 15 '20 at 19:55
What is the issue, exactly? Which part are you struggling with? — AMC, Feb 15 '20 at 20:39
You don't have a tuple of arrays. You have a list of tuples of one array each. — MisterMiyagi, Feb 15 '20 at 21:35

score 0 · Accepted Answer · answered Feb 15 '20 at 19:58

0

Each item in T is a tuple of length 1, so just index it, like this:

>>> len(T[1][0])
10

To be clear:

>>> T[1]
(array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]),)
>>> T[1][0]
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

answered Feb 15 '20 at 19:58

wjandrea

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niranjan patidar · Answer 2 · 2020-02-16T06:11:10.207

0

You can try comprehension concept as well,like

arr_length = [len(i[0]) for i in T]

edited Feb 16 '20 at 06:11

answered Feb 15 '20 at 20:28

niranjan patidar

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*`len(i)` -> `len(i[0])` since `i` is a tuple – wjandrea Feb 15 '20 at 20:50

How to find the length of array within a tuple

2 Answers2