pub fn euler_graph_to_euler_circuit(eg: &EulerGraph) -> EulerCircuit {
    // If there is one or less nodes, there's no place for edges.
    if eg.node_count() == 0 || eg.node_count() == 1 {
        return vec![];
    }

    // Begin the traversals to build the circuit, starting at `v0`.
    let start_n = eg
        .node_indices()
        .next()
        .expect("expected at least two nodes, found none");
    let mut visited: HashSet<EdgeIndex> = HashSet::new();
    let mut visit_order: Vec<EdgeIndex> = vec![];
    loop {
        // Find a node in the visit order with untraversed edges, or pick one to begin if we're
        // just starting. We will do a traversal from this node. Keep track of where in the
        // existing `visit_order` we should merge this new traversal. If there are no nodes with
        // untraversed edges, we are done.
        let (merge_ix, n) = match visit_order.is_empty() {
            true => (0, start_n),
            false => {
                match visit_order
                    .iter()
                    .map(|&e| eg.raw_edges()[e.index()].source())
                    .enumerate()
                    .find(|&(_i, n)| eg.edges(n).any(|e| !visited.contains(&e.id())))
                {
                    Some(n) => n,
                    None => break,
                }
            }
        };

        let traversal = traverse_unvisited(n, eg, &mut visited);
        let new_visit_order = visit_order
            .iter()
            .take(merge_ix)
            .cloned()
            .chain(traversal)
            .chain(visit_order.iter().skip(merge_ix).cloned())
            .collect();
        visit_order = new_visit_order;
    }

    visit_order
}
/// Given a Euler Graph describing the vector image to be drawn, return the optimal Euler Circuit
/// describing the path over which the laser should travel.
///
/// This is Hierholzer's Algorithm with the amendment that during traversal of each vertex the edge
/// with the closest angle to a straight line is always chosen.
Given a Euler Graph describing the vector image to be drawn, return the optimal Euler Circuit
describing the path over which the laser should travel.

This is Hierholzer's Algorithm with the amendment that during traversal of each vertex the edge
with the closest angle to a straight line is always chosen.
Given a Euler Graph describing the vector image to be drawn return the optimal Euler Circuit describing the path over which the laser should travel . This is Hierholzer ' s Algorithm with the amendment that during traversal of each vertex the edge with the closest angle to a straight line is always chosen .
pub fn euler_graph_to_euler_circuit(eg: &EulerGraph) -> EulerCircuit {
    // If there is one or less nodes, there's no place for edges.
    if eg.node_count() == 0 || eg.node_count() == 1 {
        return vec![];
    }
    // Begin the traversals to build the circuit, starting at `v0`.
    let start_n = eg
        .node_indices()
        .next()
        .expect("expected at least two nodes, found none");
    let mut visited: HashSet<EdgeIndex> = HashSet::new();
    let mut visit_order: Vec<EdgeIndex> = vec![];
    loop {
        // Find a node in the visit order with untraversed edges, or pick one to begin if we're
        // just starting. We will do a traversal from this node. Keep track of where in the
        // existing `visit_order` we should merge this new traversal. If there are no nodes with
        // untraversed edges, we are done.
        let (merge_ix, n) = match visit_order.is_empty() {
            true => (0, start_n),
            false => {
                match visit_order
                    .iter()
                    .map(|&e| eg.raw_edges()[e.index()].source())
                    .enumerate()
                    .find(|&(_i, n)| eg.edges(n).any(|e| !visited.contains(&e.id())))
                {
                    Some(n) => n,
                    None => break,
                }
            }
        };
        let traversal = traverse_unvisited(n, eg, &mut visited);
        let new_visit_order = visit_order
            .iter()
            .take(merge_ix)
            .cloned()
            .chain(traversal)
            .chain(visit_order.iter().skip(merge_ix).cloned())
            .collect();
        visit_order = new_visit_order;
    }
    visit_order
}
pub fn euler_graph_to_euler_circuit ( eg : & EulerGraph ) -> EulerCircuit { // If there is one or less nodes, there's no place for edges. if eg . node_count ( ) == 0 || eg . node_count ( ) == 1 { return vec ! [ ] ; } // Begin the traversals to build the circuit, starting at `v0`. let start_n = eg . node_indices ( ) . next ( ) . expect ( " " ) ; let mut visited : HashSet < EdgeIndex > = HashSet :: new ( ) ; let mut visit_order : Vec < EdgeIndex > = vec ! [ ] ; loop { // Find a node in the visit order with untraversed edges, or pick one to begin if we're // just starting. We will do a traversal from this node. Keep track of where in the // existing `visit_order` we should merge this new traversal. If there are no nodes with // untraversed edges, we are done. let ( merge_ix , n ) = match visit_order . is_empty ( ) { true => ( 0 , start_n ) , false => { match visit_order . iter ( ) . map ( | & e | eg . raw_edges ( ) [ e . index ( ) ] . source ( ) ) . enumerate ( ) . find ( | & ( _i , n ) | eg . edges ( n ) . any ( | e | ! visited . contains ( & e . id ( ) ) ) ) { Some ( n ) => n , None => break , } } } ; let traversal = traverse_unvisited ( n , eg , & mut visited ) ; let new_visit_order = visit_order . iter ( ) . take ( merge_ix ) . cloned ( ) . chain ( traversal ) . chain ( visit_order . iter ( ) . skip ( merge_ix ) . cloned ( ) ) . collect ( ) ; visit_order = new_visit_order ; } visit_order }
Given a Euler Graph describing the vector image to be drawn, return the optimal Euler Circuit
describing the path over which the laser should travel.
Given a Euler Graph describing the vector image to be drawn return the optimal Euler Circuit describing the path over which the laser should travel .
eg
&EulerGraph
eg
&EulerGraph