Is there a direct, fast way to "map" list to MatrixXd?

Question

I am looking for a direct, fast method to convert a list<VectorXd> to MatrixXd. How can I do that?

Map<Eigen::MatrixXd> listV(list<VectorXd>)

Doesn't compile.

I am also thinking about iterating over the list<VectorXd> and fill in the MatrixXd necessarily, but that could be slow and unnecessary.

Although I agree that this answer is helpful to me in resolving my question, but I don't agree that the parent question is a duplicate for this one. The way to access list and vector can be different, so the question should remain open because the answer is different.

Possible duplicate of [Eigen and std::vector](http://stackoverflow.com/questions/33668485/eigen-and-stdvector) — Avi Ginsburg, Feb 24 '17 at 04:29

score 1 · Accepted Answer · answered Feb 24 '17 at 07:53

1

No that's not possible because the elements of the std::list are not sequentially stored in memory. So you'll have to process it one column at once, using Map on the std::vector. So only one loop over the elements of the std::list.

answered Feb 24 '17 at 07:53

ggael

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Is there a direct, fast way to "map" list to MatrixXd?

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