public static List <string> IntersectOnColKeys(ref ShoMatrix m1, ref Matrix <string, string, double> m2) { IList <string> cidsPhen = m2.ColKeys; IList <string> cidsSnp = m1.ColKeys; List <string> cids = cidsPhen.Intersect(cidsSnp).ToList(); m1 = m1.SelectColsView(cids).AsShoMatrix(); m2 = m2.SelectColsView(cids).AsShoMatrix(); return(cids); }