Trim a dataset based on array of subject IDs that correspond to rows to keep in matrix

Hi,

I have a large matrix, where the first column is subject IDs (around 2000 people). For a particular analysis, I'd only like to look at 800 specific people. I have an array of these subject IDs. Basically, I'd like to compare the list of subject IDs I want to keep to the subject ID column in the matrix. If a subject ID isn't present in the list, I want to delete that subject's entire row from the matrix. I've done logical indexing and for loops for this type of thing on a smaller scale, but can't seem to think of how to do this efficiency on a large scale.

Thank you!

Answer 1

[dpb]

 b=a(ismember(a,list),:);  % see doc ismember for details