geometry:null about mapshaper

[makc]

I have found the checkbox :) But it is not really what I would like to keep, it keeps every single island. It makes no sense in case of Chile for example...

[mbloch]

Thanks for writing. I agree it's generally not useful to retain all of the parts of a multi-part shape. I've been planning to update the "prevent shape removal" option so that it retains the part with the largest original area and allows other parts to disappear at high simplification. Would that be preferable to you?

[makc]

So far I tried

MapShaper.calcPointRetentionData = function(shapes, retainedPointCounts, arcCounts) {
  Utils.forEach(shapes, function(shape, shapeId) {
    if (!shape) return;
    var l = 0, a;
    for (var i=0, n=shape.length; i<n; i++) {
      var arcs = shape[i];
      // if a part has 3 or more arcs, assume it won't collapse...
      // TODO: look into edge cases where this isn't true
      if (arcs.length <= 2) { // && pathData[pathId].isPrimary) {
          if (l < arcs.length) {
              l = arcs.length; a = arcs;
          }
      }
    }
    if (a) {
      MapShaper.calcRetainedCountsForRing(a, retainedPointCounts, arcCounts);
    }
  });
  return retainedPointCounts;
};

but it has bad effects such as continental Greece disappearing while leaving Crete there, for example. Also whole single-island states like Cuba disappear any way, probably because they start as complex shape originally.

I think the area check would be great, but might not be enough in the end, too. While helping the above Greece and Cube problem, it will do nothing for disappearing Hawaii, for example.

[makc]

Well, you could always split Hawaii in the source and then merge it back... so I guess go for area check 👍

[mbloch]

I pushed an update (41fe109) that changes the behavior of the "prevent shape removal" option so that it only protects the largest ring of multi-ring polygon features. I just added a comment to issue #14 with an explanation.

[makc]

This actually worked very good :) Andorra is now very small triangle, but it exists.