private void testCorrectnessOfErrorFunction(List<Number> inputList) throws Exception {
int inRange = 0;
int numberOfRuns = 1000;
double sampleRatio = 1 / (double) WEIGHT;
double actual = getExpectedValue(inputList);
Random rand = new Random(1);
for (int i = 0; i < numberOfRuns; i++) {
// Compute Sampled Value using sampledList (numberOfRuns times)
ImmutableList.Builder<Number> sampledList = ImmutableList.builder();
for (Number x : inputList) {
if (rand.nextDouble() < sampleRatio) {
sampledList.add(x);
}
}
BlockBuilder builder = getType().createBlockBuilder(new BlockBuilderStatus());
for (Number sample : sampledList.build()) {
if (getType() == BIGINT) {
BIGINT.writeLong(builder, sample.longValue());
} else if (getType() == DOUBLE) {
DOUBLE.writeDouble(builder, sample.doubleValue());
} else {
throw new AssertionError("Can only handle longs and doubles");
}
}
Page page = new Page(builder.build());
page = OperatorAssertion.appendSampleWeight(ImmutableList.of(page), WEIGHT).get(0);
Accumulator accumulator =
getFunction()
.bind(
ImmutableList.of(0),
Optional.<Integer>absent(),
Optional.of(page.getChannelCount() - 1),
getConfidence())
.createAccumulator();
accumulator.addInput(page);
Block result = accumulator.evaluateFinal();
String approxValue =
BlockAssertions.toValues(accumulator.getFinalType(), result).get(0).toString();
double approx = Double.parseDouble(approxValue.split(" ")[0]);
double error = Double.parseDouble(approxValue.split(" ")[2]);
// Check if actual answer lies within [approxAnswer - error, approxAnswer + error]
if (Math.abs(approx - actual) <= error) {
inRange++;
}
}
BinomialDistribution binomial = new BinomialDistribution(numberOfRuns, getConfidence());
int lowerBound = binomial.inverseCumulativeProbability(0.01);
int upperBound = binomial.inverseCumulativeProbability(0.99);
assertTrue(
lowerBound < inRange && inRange < upperBound,
String.format(
"%d out of %d passed. Expected [%d, %d]",
inRange, numberOfRuns, lowerBound, upperBound));
}
