How to extract all the elements in a vector whose index is 1?

Given a vector R:

R=[0.7 9 8 34 2]'; ranks=[1 2 2 2 3];

Where the first element in ranks crossponds to the rank of the first element in R and the second element in ranks crossponds to the second element in R and so on.

I need to extract all the elements whose ranks are 2 and put them in a vector but I need a general way because the sizes of the vectors R and ranks will vary

I appreciate your help

thank you

Answer 1

[Adam Danz]

x = R(ranks == 2)

Indexing is one of the most important tools in Matlab. This is a good resource to get you started.

https://www.mathworks.com/company/newsletters/articles/matrix-indexing-in-matlab.html