4 ms·

Very neat animation. Is it always the same graph, if you reload ? (with different initial random placements, I mean) In one case, I observed an edge coming to

by ableal 17y ago

Very neat animation. Is it always the same graph, if you reload ? (with different initial random placements, I mean) In one case, I observed an edge coming to rest just across an unconnected (to that edge) node. Might be hard to detect/work around ... [Many moons ago, for an exercise, implemented a force-directed placement, with team-mates doing Kernighan-Lin min-cut (also fast) and simulated annealing (slow) ...] P.S. Two observations: - You highlight the node on mouse over. If the edges connected directly to that node were also highlighted, it would palliate the false connection problem. - Adding some edge-edge repulsion ? Sometimes edges cross, and one of them could be flipped to another side for a locally planar solution.

dhotson 17y ago
Yep, it's currently the same hardcoded graph each time. The node starting positions are random so you get a slightly different layout each time. I was thinking about making edges repel nodes in some way to avoid the problem you mentioned. I'll have to experiment some more..
- jonp 17y ago
  That's really neat. I hit the same problem of crossing edges when doing this a while ago (in Python rather than JavaScript). Rather than trying to get everything done automatically by the code I added the ability to click and drag a point. So the algorithm gets you close to a good layout and you can then make adjustments to avoid unwanted crossings. It reminds me of an old HN comment "think cyborg, not robot" (http://news.ycombinator.com/item?id=164833 http://news.ycombinator.com/item?id=164833).
  - dhotson 17y ago
    Thanks jonp. :-) I think that's a good idea. The force directed layout algorithm isn't bullet proof, but it's a good approximate layout for a human to tweak.
    - ableal 17y ago
      Just remembered this discussion http://news.ycombinator.com/item?id=1218376 http://news.ycombinator.com/item?id=1218376 also featured a force-directed graph layout algorithm, with brief paper and all. Just in case you missed it.

by ableal 17y ago

dhotson 17y ago

Yep, it's currently the same hardcoded graph each time. The node starting positions are random so you get a slightly different layout each time. I was thinking about making edges repel nodes in some way to avoid the problem you mentioned. I'll have to experiment some more..

jonp 17y ago
That's really neat. I hit the same problem of crossing edges when doing this a while ago (in Python rather than JavaScript). Rather than trying to get everything done automatically by the code I added the ability to click and drag a point. So the algorithm gets you close to a good layout and you can then make adjustments to avoid unwanted crossings. It reminds me of an old HN comment "think cyborg, not robot" (http://news.ycombinator.com/item?id=164833 http://news.ycombinator.com/item?id=164833).
- dhotson 17y ago
  Thanks jonp. :-) I think that's a good idea. The force directed layout algorithm isn't bullet proof, but it's a good approximate layout for a human to tweak.
  - ableal 17y ago
    Just remembered this discussion http://news.ycombinator.com/item?id=1218376 http://news.ycombinator.com/item?id=1218376 also featured a force-directed graph layout algorithm, with brief paper and all. Just in case you missed it.