calculate max or min of subset of a matrix

calc.maxmin(r2, L1, L2 = L1, fun = max)

Arguments

r2	matrix, with row/column names which are members of L1, L2
L1	first list of vectors of snps
L2	second list vectors of snps
fun	max or min, but could be another function that returns a scalar. unquoted.

Value

smaller matrix indexed by elements of L1 (rows) and L2 (columns)