code: function(sbm) {
      // create the matrix
      var mat = {}
      mat.x = sbm.y
      mat.y = sbm.x
      mat.data = []
      // populate
      for (var i = 0; i < mat.x; i++) {
        mat.data.push([])
        for (var j = 0; j < mat.y; j++) {
          if (_.includes(sbm.data[j], i)) {
              mat.data[i].push(j)
          }
        }
      }
      return mat
    }
docs: transposes the matrix