plot-base/src/commonMain/kotlin/org/jetbrains/letsPlot/core/plot/base/stat/Density2dStat.kt [17:75]:
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    bandWidthX: Double?,
    bandWidthY: Double?,
    bandWidthMethod: DensityStat.BandWidthMethod,  // Used is `bandWidth` is not set.
    adjust: Double,
    kernel: DensityStat.Kernel,
    nX: Int,
    nY: Int,
    isContour: Boolean,
    binCount: Int,
    binWidth: Double

) : AbstractDensity2dStat(
    bandWidthX = bandWidthX,
    bandWidthY = bandWidthY,
    bandWidthMethod = bandWidthMethod,
    adjust = adjust,
    kernel = kernel,
    nX = nX,
    nY = nY,
    isContour = isContour,
    binCount = binCount,
    binWidth = binWidth,
    defaultMappings = DEF_MAPPING
) {

    override fun apply(data: DataFrame, statCtx: StatContext, messageConsumer: (s: String) -> Unit): DataFrame {
        if (!hasRequiredValues(data, Aes.X, Aes.Y)) {
            return withEmptyStatValues()
        }

        val xs = data.getNumeric(TransformVar.X)
        val ys = data.getNumeric(TransformVar.Y)
        val finiteIndices = xs.indicesOf(SeriesUtil::isFinite) intersect ys.indicesOf(SeriesUtil::isFinite)

        // if no data, return empty
        if (finiteIndices.isEmpty()) {
            return withEmptyStatValues()
        }

        val xVector = xs.slice(finiteIndices).requireNoNulls()
        val yVector = ys.slice(finiteIndices).requireNoNulls()
        val groupWeight = BinStatUtil.weightVector(data)
            .slice(finiteIndices)
            .map { SeriesUtil.finiteOrNull(it) ?: 0.0 }

        val xRange = statCtx.overallXRange()
        val yRange = statCtx.overallYRange()

        val (stepsX, stepsY, densityMatrix) = density2dGrid(xVector, yVector, groupWeight, xRange!!, yRange!!)

        val statX = ArrayList<Double>()
        val statY = ArrayList<Double>()
        val statDensity = ArrayList<Double>()

        for (row in 0 until nY) {
            for (col in 0 until nX) {
                statX.add(stepsX[col])
                statY.add(stepsY[row])
                statDensity.add(densityMatrix.getEntry(row, col) / SeriesUtil.sum(groupWeight))
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plot-base/src/commonMain/kotlin/org/jetbrains/letsPlot/core/plot/base/stat/Density2dfStat.kt [17:75]:
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    bandWidthX: Double?,
    bandWidthY: Double?,
    bandWidthMethod: DensityStat.BandWidthMethod,  // Used is `bandWidth` is not set.
    adjust: Double,
    kernel: DensityStat.Kernel,
    nX: Int,
    nY: Int,
    isContour: Boolean,
    binCount: Int,
    binWidth: Double

) : AbstractDensity2dStat(
    bandWidthX = bandWidthX,
    bandWidthY = bandWidthY,
    bandWidthMethod = bandWidthMethod,
    adjust = adjust,
    kernel = kernel,
    nX = nX,
    nY = nY,
    isContour = isContour,
    binCount = binCount,
    binWidth = binWidth,
    defaultMappings = DEF_MAPPING
) {

    override fun apply(data: DataFrame, statCtx: StatContext, messageConsumer: (s: String) -> Unit): DataFrame {
        if (!hasRequiredValues(data, Aes.X, Aes.Y)) {
            return withEmptyStatValues()
        }

        val xs = data.getNumeric(TransformVar.X)
        val ys = data.getNumeric(TransformVar.Y)
        val finiteIndices = xs.indicesOf(SeriesUtil::isFinite) intersect ys.indicesOf(SeriesUtil::isFinite)

        // if no data, return empty
        if (finiteIndices.isEmpty()) {
            return withEmptyStatValues()
        }

        val xVector = xs.slice(finiteIndices).requireNoNulls()
        val yVector = ys.slice(finiteIndices).requireNoNulls()
        val groupWeight = BinStatUtil.weightVector(data)
            .slice(finiteIndices)
            .map { SeriesUtil.finiteOrNull(it) ?: 0.0 }

        val xRange = statCtx.overallXRange()
        val yRange = statCtx.overallYRange()

        val (stepsX, stepsY, densityMatrix) = density2dGrid(xVector, yVector, groupWeight, xRange!!, yRange!!)

        val statX = ArrayList<Double>()
        val statY = ArrayList<Double>()
        val statDensity = ArrayList<Double>()

        for (row in 0 until nY) {
            for (col in 0 until nX) {
                statX.add(stepsX[col])
                statY.add(stepsY[row])
                statDensity.add(densityMatrix.getEntry(row, col) / SeriesUtil.sum(groupWeight))
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