Add 'pad' parameter to the StepGeom (for the eCDF).

demo/plot-common/src/commonMain/kotlin/demo/plot/common/model/plotConfig/ECDF.kt

@@ -13,6 +13,7 @@ class ECDF {
  return listOf(
  basic(),
  withInterpolation(),
+ withGrouping()
  )
  }
 
@@ -29,7 +30,8 @@ class ECDF {
  'layers': [
  {
  'geom': 'step',
- 'stat': 'ecdf'
+ 'stat': 'ecdf',
+ 'pad': true
  }
  ]
  }
@@ -55,7 +57,36 @@ class ECDF {
  {
  'geom': 'step',
  'stat': 'ecdf',
- 'n': 10
+ 'n': 10,
+ 'pad': true,
+ 'direction': 'vh'
+ }
+ ]
+ }
+ """.trimIndent()
+
+ val plotSpec = HashMap(parsePlotSpec(spec))
+ plotSpec["data"] = Iris.df
+ return plotSpec
+
+ }
+
+ private fun withGrouping(): MutableMap<String, Any> {
+ val spec = """
+ {
+ 'kind': 'plot',
+ 'mapping': {
+ 'x': 'sepal length (cm)',
+ 'color': 'target'
+ },
+ 'ggtitle': {
+ 'text': 'With additional grouping'
+ },
+ 'layers': [
+ {
+ 'geom': 'step',
+ 'stat': 'ecdf',
+ 'pad': true
  }
  ]
  }

plot-base/src/commonMain/kotlin/org/jetbrains/letsPlot/core/plot/base/geom/StepGeom.kt

@@ -5,14 +5,18 @@
 
 package org.jetbrains.letsPlot.core.plot.base.geom
 
+import org.jetbrains.letsPlot.commons.geometry.DoubleVector
 import org.jetbrains.letsPlot.core.plot.base.*
+import org.jetbrains.letsPlot.core.plot.base.geom.util.GeomHelper
 import org.jetbrains.letsPlot.core.plot.base.geom.util.GeomUtil
 import org.jetbrains.letsPlot.core.plot.base.geom.util.LinesHelper
 import org.jetbrains.letsPlot.core.plot.base.geom.util.TargetCollectorHelper
 import org.jetbrains.letsPlot.core.plot.base.render.SvgRoot
+import org.jetbrains.letsPlot.datamodel.svg.dom.SvgLineElement
 
 class StepGeom : LineGeom() {
  private var myDirection = DEF_DIRECTION
+ var padded = DEF_PADDED
 
  fun setDirection(dir: String) {
  myDirection = Direction.toDirection(dir)
@@ -33,10 +37,63 @@ class StepGeom : LineGeom() {
 
  root.appendNodes(linePaths)
 
+ if (padded) {
+ GeomUtil.withDefined(dataPoints, Aes.X, Aes.Y).groupBy(DataPointAesthetics::group).forEach { (_, groupPoints) ->
+ for (line in getPads(groupPoints, pos, coord, ctx)) {
+ root.add(line)
+ }
+ }
+ }
+
  val targetCollectorHelper = TargetCollectorHelper(GeomKind.STEP, ctx)
  targetCollectorHelper.addPaths(pathDataList)
  }
 
+ private fun getPads(
+ dataPoints: Iterable<DataPointAesthetics>,
+ pos: PositionAdjustment,
+ coord: CoordinateSystem,
+ ctx: GeomContext
+ ): List<SvgLineElement> {
+ val pads: MutableList<SvgLineElement> = mutableListOf()
+
+ val helper = GeomHelper(pos, coord, ctx).createSvgElementHelper()
+ val viewPort = overallAesBounds(ctx)
+ val definedPoints = GeomUtil.withDefined(dataPoints, Aes.X, Aes.Y)
+ if (!definedPoints.any()) {
+ return pads
+ }
+
+ val startPoint = definedPoints.first()
+ val startX = startPoint.x()!!
+ val startY = startPoint.y()!!
+ val endPoint = definedPoints.last()
+ val endX = endPoint.x()!!
+ val endY = endPoint.y()!!
+
+ if (startY < 0 || endY > 1) {
+ return pads
+ }
+
+ helper.createLine(
+ DoubleVector(viewPort.left, 0.0),
+ DoubleVector(startX, 0.0),
+ startPoint
+ )?.let { pads.add(it) }
+ helper.createLine(
+ DoubleVector(startX, 0.0),
+ DoubleVector(startX, startY),
+ startPoint
+ )?.let { pads.add(it) }
+ helper.createLine(
+ DoubleVector(endX, 1.0),
+ DoubleVector(viewPort.right, 1.0),
+ endPoint
+ )?.let { pads.add(it) }
+
+ return pads
+ }
+
  enum class Direction {
  HV, VH;
 
@@ -55,6 +112,7 @@ class StepGeom : LineGeom() {
  companion object {
  // default
  val DEF_DIRECTION = Direction.HV
+ const val DEF_PADDED = false
 
  const val HANDLES_GROUPS = LineGeom.HANDLES_GROUPS
  }

plot-stem/src/commonMain/kotlin/org/jetbrains/letsPlot/core/spec/GeomProviderFactory.kt

@@ -203,6 +203,9 @@ internal object GeomProviderFactory {
  if (layerConfig.hasOwn(Option.Geom.Step.DIRECTION)) {
  geom.setDirection(layerConfig.getString(Option.Geom.Step.DIRECTION)!!)
  }
+ if (layerConfig.hasOwn(Option.Geom.Step.PADDED)) {
+ geom.padded = layerConfig.getBoolean(Option.Geom.Step.PADDED, StepGeom.DEF_PADDED)
+ }
  geom
  }
 

plot-stem/src/commonMain/kotlin/org/jetbrains/letsPlot/core/spec/Option.kt

@@ -242,6 +242,7 @@ object Option {
 
  object Step {
  const val DIRECTION = "direction"
+ const val PADDED = "pad"
  }
 
  object Segment {