public PoissonSamplerCache withRange()

in commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/distribution/PoissonSamplerCache.java [349:387]

• 28 lines of code
• 5 McCabe index (conditional complexity)

    public PoissonSamplerCache withRange(double minMean,
                                         double maxMean) {
        if (values == null) {
            // Nothing to reuse
            return new PoissonSamplerCache(minMean, maxMean);
        }
        checkMeanRange(minMean, maxMean);

        // The cache can only be used for the LargeMeanPoissonSampler.
        if (maxMean < PoissonSampler.PIVOT) {
            return new PoissonSamplerCache(0, 0);
        }

        // Convert the mean into integers.
        // Note the minimum is clipped to the algorithm switch point.
        final int withMinN = (int) Math.floor(Math.max(minMean, PoissonSampler.PIVOT));
        final int withMaxN = (int) Math.floor(maxMean);
        final LargeMeanPoissonSamplerState[] states =
                new LargeMeanPoissonSamplerState[withMaxN - withMinN + 1];

        // Preserve values from the current array to the next
        final int currentIndex;
        final int nextIndex;
        if (this.minN <= withMinN) {
            // The current array starts before the new array
            currentIndex = withMinN - this.minN;
            nextIndex = 0;
        } else {
            // The new array starts before the current array
            currentIndex = 0;
            nextIndex = this.minN - withMinN;
        }
        final int length = Math.min(values.length - currentIndex, states.length - nextIndex);
        if (length > 0) {
            System.arraycopy(values, currentIndex, states, nextIndex, length);
        }

        return new PoissonSamplerCache(withMinN, withMaxN, states);
    }