CODEWITHSUNDEEP
c++matrixarmadillo
Daniel
Daniel

Reputation: 84

Armadillo - how to create Matrix from sparse format?

Let's say I have a sparse matrix. I have it defined in the following CSV format:

row,column,value 1,1,5 1,2,10

In this case, the point (1,1) is equal to 5 and the point (1,2) is equal to 10.

What is an efficient way to create a matrix from this format (assuming thousands or hundreds of thousands of rows)?

In other words, I want the equivalent of running full(spconvert(m)) in Matlab, where m is the above matrix.

Upvotes: 1

Views: 384

Answers (1)

ks1322
ks1322

Reputation: 35716

You need to use one of batch insertion constructors of sp_mat sparse matrix class. There is an example of how to do it in documentation:

// batch insertion of two values at (5, 6) and (9, 9)
umat locations;
locations << 5 << 9 << endr
          << 6 << 9 << endr;

vec values;
values << 1.5 << 3.2 << endr;

sp_mat X(locations, values);

Upvotes: 2

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