Add GeometryCollection dimension cache #1103
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dbaston
reviewed
Dec 20, 2024
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| public boolean hasDimension(int dim) { | ||
| if (dim == Dimension.A && hasA) return true; |
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I don't understand the dim == x check here. If we have a mixed polygon/line collection, isn't dim equal to Dimension.A but hasDimension(Dimension.L) should be true?
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dim is the argument to hasDimension. So for hasDimension(Dimension.L) dim is 1, and that matches
dim == Dimension.L && hasL
Actually this logic would be simpler as:
if (dim == Dimension.A) return hasA;
if (dim == Dimension.L) return hasL;
if (dim == Dimension.P) return hasP;
return false;
@dbaston do you agree?
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Or even better:
switch (dim) {
case Dimension.A: return hasA;
case Dimension.L: return hasL;
case Dimension.P: return hasP;
}
return false;
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Thank you, I was pretty sure I was having a brain failure of sorts.
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Heterogeneous (mixed)
GeometryCollections have to use an O(n) algorithm to determine the dimensions of the elements. This causes performance issues in algorithms which use the dimension of the collection (see #1100).This PR solves this problem by caching the computed dimensions of a GeometryCollection. It adds a single reference to each collection object, but the actual cache is lazily created when dimension information is accessed.
For example, for a
CoverageUnionof a grid of 1M rectangles this improves the performance from 17 s to 370 ms (45x).Fixes #1100