Revert "Use numpy PyReadonlyArray to avoid one, unnecessary copy"

This reverts commit 53842ef.

src/tree.rs

@@ -11,7 +11,6 @@
 // under the License.
 
 use hashbrown::HashSet;
-use numpy::PyReadonlyArray1;
 use std::cmp::Ordering;
 use std::collections::VecDeque;
 
@@ -174,29 +173,21 @@ fn _minimum_spanning_tree(
 pub fn bipartition_tree(
  _py: Python,
  spanning_tree: &graph::PyGraph,
- pops: PyReadonlyArray1<f64>,
+ pops: Vec<f64>,
  pop_target: f64,
  epsilon: f64,
 ) -> PyResult<Vec<(usize, Vec<usize>)>> {
- // See: https://github.com/Qiskit/retworkx/pull/572#discussion_r883643134
- // There should be no other views of pops, so this should be fine
- unsafe {
- Ok(_bipartition_tree(
- spanning_tree,
- pops.as_slice_mut()?,
- pop_target,
- epsilon,
- ))
- }
+ Ok(_bipartition_tree(spanning_tree, pops, pop_target, epsilon))
 }
 
 /// Internal _bipartition_tree implementation.
 fn _bipartition_tree(
  spanning_tree: &graph::PyGraph,
- pops: &mut [f64],
+ pops: Vec<f64>,
  pop_target: f64,
  epsilon: f64,
 ) -> Vec<(usize, Vec<usize>)> {
+ let mut pops = pops;
  let spanning_tree_graph = &spanning_tree.graph;
  let mut same_partition_tracker: Vec<Vec<usize>> =
  vec![vec![]; spanning_tree_graph.node_bound()]; // Keeps track of all all the nodes on the same side of the partition
@@ -275,18 +266,17 @@ pub fn bipartition_graph_mst(
  py: Python,
  graph: &graph::PyGraph,
  weight_fn: PyObject,
- pops: PyReadonlyArray1<f64>,
+ pops: Vec<f64>,
  pop_target: f64,
  epsilon: f64,
 ) -> PyResult<Vec<(usize, Vec<usize>)>> {
  let mut balanced_nodes: Vec<(usize, Vec<usize>)> = vec![];
  let mut mst = (*graph).clone();
- let pops_slice: Vec<f64> = pops.to_vec()?;
 
  while balanced_nodes.is_empty() {
  mst.graph.clear_edges();
  _minimum_spanning_tree(py, graph, &mut mst, Some(weight_fn.clone()), 1.0)?;
- balanced_nodes = _bipartition_tree(&mst, &mut pops_slice.clone(), pop_target, epsilon);
+ balanced_nodes = _bipartition_tree(&mst, pops.clone(), pop_target, epsilon);
  }
 
  Ok(balanced_nodes)