Hi,(adsbygoogle = window.adsbygoogle || []).push({});

I am currently dealing with really huge (~ 80,000 x 80,000) sparse matrices. I this context I need to read the number of non-default values in each row.

When Accessing the i-th row of a SparseArray, this information is given.

E.g.

test = SparseArray[{{1, 1} -> 3, {1, 5} -> 2, {5, 3} -> 1}];

test[[1]]

returns SparseArray[<2>, {5}]

However, I fail to access the number of entries (here 2) to assign it to a variable.

I did not find any information in the documentation so far.

Does anyone have an idea?

Thx

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Mathematica SparseArray Access Non-Default Values

**Physics Forums | Science Articles, Homework Help, Discussion**