Remove N^2 uniqueness checks in interpolators #2031
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jodastephen
requested changes
Jul 22, 2019
| */ | ||
| public static double[] noDuplicates(double[] argument, String name) { | ||
| notNull(argument, name); | ||
| if (argument.length > 0 && DoubleStream.of(argument).distinct().count() != argument.length) { |
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I wouldn't have thought DoubleStream.of(argument).distinct().count() was that fast?
modules/collect/src/main/java/com/opengamma/strata/collect/DoubleArrayMath.java
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| @@ -476,6 +562,10 @@ private static void swap(double[] keys, double[] values, int first, int second) | |||
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| /** | |||
| * Return the array lengths if they are the same, otherwise throws an {@code IllegalArgumentException}. | |||
| * | |||
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I would have just changed this to a // comment
| double[] yValuesSrt = new double[nDataPts]; | ||
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| xValuesSrt = Arrays.copyOf(xValues, nDataPts); | ||
| double[] xValuesSrt = Arrays.copyOf(xValues, nDataPts); |
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I suspect xValues.clone() might be quicker in cases like this.
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Apparently .clone() may add a cast (since it's implicitly overriden from the Object::clone() method)
Arrays.copyOf() delegates to System.arrayCopy which is native, and doesn't involve a cast.
I'd have to benchmark to be sure.
Although https://stackoverflow.com/questions/12157300/clone-or-arrays-copyof says they are equivalent post JIT
| for (int j = i + 1; j < nDataPts; ++j) { | ||
| ArgChecker.isFalse(xValues[i] == xValues[j], "Data should be distinct"); | ||
| } | ||
| if (DoubleStream.of(xValues).distinct().count() != xValues.length) { |
jodastephen
approved these changes
Jul 29, 2019
…bleArrayMath.java Co-Authored-By: Stephen Colebourne <stephen@opengamma.com>
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Not sure this is the best implementation - still seems a little boilerplatey.
Could definitely be streamlined with more ArgChecker methods, potentially ones that assert that a double array is sorted, unique, and doesn't contain NaN or infinity, but maybe that's overstepping what ArgChecker is responsible for.