Eigen: mask an array

Question

Is it possible to mask an array in Eigen as in Matlab?

Something like

ArrayXd arrayA = ArrayXd::Random(10, 5);
ArrayXi mask = ArrayXi::Zero(arrayA.rows         


        

Answer 1

From the Quick Reference

(R.array() < s).select(P,Q);  // (R < s ? P : Q)

so, in your case it would be

(arrayA > 5).select(mask, arrayA)

Answer 2

I found some reference here http://igl.ethz.ch/projects/libigl/matlab-to-eigen.html

For B = IM(A), they suggest:

B = A.unaryExpr(bind1st(mem_fun( 
    static_cast<VectorXi::Scalar&(VectorXi::*)(VectorXi::Index)>
    (&VectorXi::operator())), &IM)).eval();

But it's not a generalized solution (and actually I couldn't try it )