operation producing dublicate nodes in ways

[mdk]

I use JOSM 4021, but the problem exists much longer.

I attached an osm file to see the necessary operations. Use the validator to see the problem.

1. way: a normal way with 5 nodes

2. way: the same way where node '1' and '2' are merged (select '2', SHIFT-Select '1', press 'M') this way still has 5 nodes.

3. way: deleteion of node '3'. The result has now 4 nodes containing the merged node '1;2' twice. This may be one reason for the "dublicate node in way" errors.

4. way: starting from way 2 and merging '3' with '1;2'. This time we don't have a dublicate node error and the way has only 3 nodes.

To avoid the dublicate node errors there is a simple check to be done on deleting a node (pseudo code):

delete(a: Node) {
  for each way w containing a do {
    int i = w.Index(a);
    if w.Node(i-1) = w.Node(i+1) {
      // the node before and after a are the same, so we can remove one of them
      w.removeNode(w.Node(i+1));
    }
    // remove node a from the way
    w.removeNode(a);
  } 
}

[Zverikk]

This was probably fixed in [4053]. Please try this with the latest version of JOSM.

[stoecker]

Closed as duplicate of #6219.