i have a distance matrix that is 1000x1000 in dimension and symmetric with 0s along the diagonal. i want to form groupings of distances (clusters) by simultaneously reordering the rows and columns of the matrix. this is like reordering a matrix before you visualize its clusters with a heatmap. i feel like this should be an easy problem, but i am not having much luck finding code that does the permutations online. can anyone help?