this.findRangesForChangeDetectionsWithWelchsTTest = function()

in resources/perf.webkit.org/public/shared/statistics.js [149:183]
31 lines of code
8 McCabe index (conditional complexity)

    this.findRangesForChangeDetectionsWithWelchsTTest = function (values, segmentations, oneSidedPossibility=0.99) {
        if (!values.length)
            return [];

        const selectedRanges = [];
        const twoSidedFromOneSidedPossibility = 2 * oneSidedPossibility - 1;

        for (let i = 1; i + 2 < segmentations.length; i += 2) {
            let found = false;
            const previousMean = segmentations[i].value;
            const currentMean = segmentations[i + 1].value;
            console.assert(currentMean != previousMean);
            const currentChangePoint = segmentations[i].seriesIndex;
            const start = segmentations[i - 1].seriesIndex;
            const end = segmentations[i + 2].seriesIndex;

            for (let leftEdge = currentChangePoint - 2, rightEdge = currentChangePoint + 2; leftEdge >= start && rightEdge <= end; leftEdge--, rightEdge++) {
                const result = this.computeWelchsT(values, leftEdge, currentChangePoint - leftEdge, values, currentChangePoint, rightEdge - currentChangePoint, twoSidedFromOneSidedPossibility);
                if (result.significantlyDifferent) {
                    selectedRanges.push({
                        startIndex: leftEdge,
                        endIndex: rightEdge - 1,
                        segmentationStartValue: previousMean,
                        segmentationEndValue: currentMean
                    });
                    found = true;
                    break;
                }
            }
            if (!found && Statistics.debuggingTestingRangeNomination)
                console.log('Failed to find a testing range at', currentChangePoint, 'changing from', previousMean, 'to', currentMean);
        }

        return selectedRanges;
    };