package org.opentrafficsim.draw.graphs;
   
   import java.util.ArrayList;
   import java.util.Arrays;
   import java.util.LinkedHashMap;
   import java.util.LinkedHashSet;
   import java.util.List;
   import java.util.Map;
   import java.util.Set;
  
  import org.djunits.unit.SpeedUnit;
  import org.djunits.value.vdouble.scalar.Duration;
  import org.djunits.value.vdouble.scalar.Length;
  import org.djunits.value.vdouble.scalar.Speed;
  import org.djunits.value.vdouble.scalar.Time;
  import org.djutils.exceptions.Throw;
  import org.djutils.logger.CategoryLogger;
  import org.opentrafficsim.draw.egtf.Converter;
  import org.opentrafficsim.draw.egtf.DataSource;
  import org.opentrafficsim.draw.egtf.DataStream;
  import org.opentrafficsim.draw.egtf.Egtf;
  import org.opentrafficsim.draw.egtf.EgtfEvent;
  import org.opentrafficsim.draw.egtf.EgtfListener;
  import org.opentrafficsim.draw.egtf.Filter;
  import org.opentrafficsim.draw.egtf.Quantity;
  import org.opentrafficsim.draw.egtf.typed.TypedQuantity;
  import org.opentrafficsim.draw.graphs.GraphPath.Section;
  import org.opentrafficsim.kpi.interfaces.LaneData;
  import org.opentrafficsim.kpi.sampling.SamplerData;
  import org.opentrafficsim.kpi.sampling.Trajectory;
  import org.opentrafficsim.kpi.sampling.Trajectory.SpaceTimeView;
  import org.opentrafficsim.kpi.sampling.TrajectoryGroup;
  
  /**
   * Class that contains data for contour plots. One data source can be shared between contour plots, in which case the
   * granularity, path, sampler, update interval, and whether the data is smoothed (EGTF) are equal between the plots.
   * <p>
   * By default the source contains traveled time and traveled distance per cell.
   * <p>
   * Copyright (c) 2013-2024 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="https://opentrafficsim.org/docs/license.html">OpenTrafficSim License</a>.
   * </p>
   * @author <a href="https://github.com/averbraeck">Alexander Verbraeck</a>
   * @author <a href="https://tudelft.nl/staff/p.knoppers-1">Peter Knoppers</a>
   * @author <a href="https://github.com/wjschakel">Wouter Schakel</a>
   */
  public class ContourDataSource
  {
  
      // *************************
      // *** GLOBAL PROPERTIES ***
      // *************************
  
      /** Space granularity values. */
      protected static final double[] DEFAULT_SPACE_GRANULARITIES = {10, 20, 50, 100, 200, 500, 1000};
  
      /** Index of the initial space granularity. */
      protected static final int DEFAULT_SPACE_GRANULARITY_INDEX = 3;
  
      /** Time granularity values. */
      protected static final double[] DEFAULT_TIME_GRANULARITIES = {1, 2, 5, 10, 20, 30, 60, 120, 300, 600};
  
      /** Index of the initial time granularity. */
      protected static final int DEFAULT_TIME_GRANULARITY_INDEX = 3;
  
      /** Initial lower bound for the time scale. */
      protected static final Time DEFAULT_LOWER_TIME_BOUND = Time.ZERO;
  
      /**
       * Total kernel size relative to sigma and tau. This factor is determined through -log(1 - p) with p ~= 99%. This means that
       * the cumulative exponential distribution has 99% at 5 times sigma or tau. Note that due to a coordinate change in the
       * Adaptive Smoothing Method, the actual cumulative distribution is slightly different. Hence, this is just a heuristic.
       */
      private static final int KERNEL_FACTOR = 5;
  
      /** Spatial kernel size. Larger value may be used when using a large granularity. */
      private static final Length SIGMA = Length.instantiateSI(300);
  
      /** Temporal kernel size. Larger value may be used when using a large granularity. */
      private static final Duration TAU = Duration.instantiateSI(30);
  
      /** Maximum free flow propagation speed. */
      private static final Speed MAX_C_FREE = new Speed(80.0, SpeedUnit.KM_PER_HOUR);
  
      /** Factor on speed limit to determine vc, the flip over speed between congestion and free flow. */
      private static final double VC_FACRTOR = 0.8;
  
      /** Congestion propagation speed. */
      private static final Speed C_CONG = new Speed(-18.0, SpeedUnit.KM_PER_HOUR);
  
      /** Delta v, speed transition region around threshold. */
      private static final Speed DELTA_V = new Speed(10.0, SpeedUnit.KM_PER_HOUR);
  
      // *****************************
      // *** CONTEXTUAL PROPERTIES ***
      // *****************************
  
      /** Sampler data. */
      private final SamplerData<?> samplerData;
 
     /** Update interval. */
     private final Duration updateInterval;
 
     /** Delay so critical future events have occurred, e.g. GTU's next move's to extend trajectories. */
     private final Duration delay;
 
     /** Path. */
     private final GraphPath<? extends LaneData<?>> path;
 
     /** Space axis. */
     final Axis spaceAxis;
 
     /** Time axis. */
     final Axis timeAxis;
 
     /** Registered plots. */
     private Set<AbstractContourPlot<?>> plots = new LinkedHashSet<>();
 
     // *****************
     // *** PLOT DATA ***
     // *****************
 
     /** Total distance traveled per cell. */
     private float[][] distance;
 
     /** Total time traveled per cell. */
     private float[][] time;
 
     /** Data of other types. */
     private final Map<ContourDataType<?, ?>, float[][]> additionalData = new LinkedHashMap<>();
 
     // ****************************
     // *** SMOOTHING PROPERTIES ***
     // ****************************
 
     /** Free flow propagation speed. */
     private Speed cFree;
 
     /** Flip-over speed between congestion and free flow. */
     private Speed vc;
 
     /** Smoothing filter. */
     private Egtf egtf;
 
     /** Data stream for speed. */
     private DataStream<Speed> speedStream;
 
     /** Data stream for travel time. */
     private DataStream<Duration> travelTimeStream;
 
     /** Data stream for travel distance. */
     private DataStream<Length> travelDistanceStream;
 
     /** Quantity for travel time. */
     private final Quantity<Duration, double[][]> travelTimeQuantity = new Quantity<>("travel time", Converter.SI);
 
     /** Quantity for travel distance. */
     private final Quantity<Length, double[][]> travelDistanceQuantity = new Quantity<>("travel distance", Converter.SI);
 
     /** Data streams for any additional data. */
     private Map<ContourDataType<?, ?>, DataStream<?>> additionalStreams = new LinkedHashMap<>();
 
     // *****************************
     // *** CONTINUITY PROPERTIES ***
     // *****************************
 
     /** Updater for update times. */
     private final GraphUpdater<Time> graphUpdater;
 
     /** Whether any command since or during the last update asks for a complete redo. */
     private boolean redo = true;
 
     /** Time up to which to determine data. This is a multiple of the update interval, which is now, or recent on a redo. */
     private Time toTime;
 
     /** Number of items that are ready. To return NaN values if not ready, and for operations between consecutive updates. */
     private int readyItems = -1;
 
     /** Selected space granularity, to be set and taken on the next update. */
     private Double desiredSpaceGranularity = null;
 
     /** Selected time granularity, to be set and taken on the next update. */
     private Double desiredTimeGranularity = null;
 
     /** Whether to smooth data. */
     private boolean smooth = false;
 
     // ********************
     // *** CONSTRUCTORS ***
     // ********************
 
     /**
      * Constructor using default granularities.
      * @param samplerData SamplerData&lt;?&gt;; sampler data
      * @param path GraphPath&lt;? extends LaneData&gt;; path
      */
     public ContourDataSource(final SamplerData<?> samplerData, final GraphPath<? extends LaneData<?>> path)
     {
         this(samplerData, Duration.instantiateSI(1.0), path, DEFAULT_SPACE_GRANULARITIES, DEFAULT_SPACE_GRANULARITY_INDEX,
                 DEFAULT_TIME_GRANULARITIES, DEFAULT_TIME_GRANULARITY_INDEX, DEFAULT_LOWER_TIME_BOUND,
                 AbstractPlot.DEFAULT_INITIAL_UPPER_TIME_BOUND);
     }
 
     /**
      * Constructor for non-default input.
      * @param samplerData SamplerData&lt;?&gt;; sampler data
      * @param delay Duration; delay so critical future events have occurred, e.g. GTU's next move's to extend trajectories
      * @param path GraphPath&lt;? extends LaneData&gt;; path
      * @param spaceGranularity double[]; granularity options for space dimension
      * @param initSpaceIndex int; initial selected space granularity
      * @param timeGranularity double[]; granularity options for time dimension
      * @param initTimeIndex int; initial selected time granularity
      * @param start Time; start time
      * @param initialEnd Time; initial end time of plots, will be expanded if simulation time exceeds it
      */
     @SuppressWarnings("parameternumber")
     public ContourDataSource(final SamplerData<?> samplerData, final Duration delay, final GraphPath<? extends LaneData<?>> path,
             final double[] spaceGranularity, final int initSpaceIndex, final double[] timeGranularity, final int initTimeIndex,
             final Time start, final Time initialEnd)
     {
         this.samplerData = samplerData;
         this.updateInterval = Duration.instantiateSI(timeGranularity[initTimeIndex]);
         this.delay = delay;
         this.path = path;
         this.spaceAxis = new Axis(0.0, path.getTotalLength().si, spaceGranularity[initSpaceIndex], spaceGranularity);
         this.timeAxis = new Axis(start.si, initialEnd.si, timeGranularity[initTimeIndex], timeGranularity);
 
         // get length-weighted mean speed limit from path to determine cFree and Vc for smoothing
         this.cFree = Speed.min(path.getSpeedLimit(), MAX_C_FREE);
         this.vc = Speed.min(path.getSpeedLimit().times(VC_FACRTOR), MAX_C_FREE);
 
         // setup updater to do the actual work in another thread
         this.graphUpdater = new GraphUpdater<>("Contour Data Source worker", Thread.currentThread(), (t) -> update(t));
     }
 
     // ************************************
     // *** PLOT INTERFACING AND GETTERS ***
     // ************************************
 
     /**
      * Returns the sampler data for an {@code AbstractContourPlot} using this {@code ContourDataSource}.
      * @return SamplerData&lt;?&gt;; the sampler
      */
     public final SamplerData<?> getSamplerData()
     {
         return this.samplerData;
     }
 
     /**
      * Returns the update interval for an {@code AbstractContourPlot} using this {@code ContourDataSource}.
      * @return Duration; update interval
      */
     final Duration getUpdateInterval()
     {
         return this.updateInterval;
     }
 
     /**
      * Returns the delay for an {@code AbstractContourPlot} using this {@code ContourDataSource}.
      * @return Duration; delay
      */
     final Duration getDelay()
     {
         return this.delay;
     }
 
     /**
      * Returns the path for an {@code AbstractContourPlot} using this {@code ContourDataSource}.
      * @return GraphPath&lt;? extends LaneData&gt;; the path
      */
     final GraphPath<? extends LaneData<?>> getPath()
     {
         return this.path;
     }
 
     /**
      * Register a contour plot to this data pool. The contour constructor will do this.
      * @param contourPlot AbstractContourPlot&lt;?&gt;; contour plot
      */
     final void registerContourPlot(final AbstractContourPlot<?> contourPlot)
     {
         ContourDataType<?, ?> contourDataType = contourPlot.getContourDataType();
         if (contourDataType != null)
         {
             this.additionalData.put(contourDataType, null);
         }
         this.plots.add(contourPlot);
     }
 
     /**
      * Returns the bin count.
      * @param dimension Dimension; space or time
      * @return int; bin count
      */
     final int getBinCount(final Dimension dimension)
     {
         return dimension.getAxis(this).getBinCount();
     }
 
     /**
      * Returns the size of a bin. Usually this is equal to the granularity, except for the last which is likely smaller.
      * @param dimension Dimension; space or time
      * @param item int; item number (cell number in contour plot)
      * @return double; the size of a bin
      */
     final synchronized double getBinSize(final Dimension dimension, final int item)
     {
         int n = dimension.equals(Dimension.DISTANCE) ? getSpaceBin(item) : getTimeBin(item);
         double[] ticks = dimension.getAxis(this).getTicks();
         return ticks[n + 1] - ticks[n];
     }
 
     /**
      * Returns the value on the axis of an item.
      * @param dimension Dimension; space or time
      * @param item int; item number (cell number in contour plot)
      * @return double; the value on the axis of this item
      */
     final double getAxisValue(final Dimension dimension, final int item)
     {
         if (dimension.equals(Dimension.DISTANCE))
         {
             return this.spaceAxis.getBinValue(getSpaceBin(item));
         }
         return this.timeAxis.getBinValue(getTimeBin(item));
     }
 
     /**
      * Returns the axis bin number of the given value.
      * @param dimension Dimension; space or time
      * @param value double; value
      * @return int; axis bin number of the given value
      */
     final int getAxisBin(final Dimension dimension, final double value)
     {
         if (dimension.equals(Dimension.DISTANCE))
         {
             return this.spaceAxis.getValueBin(value);
         }
         return this.timeAxis.getValueBin(value);
     }
 
     /**
      * Returns the available granularities that a linked plot may use.
      * @param dimension Dimension; space or time
      * @return double[]; available granularities that a linked plot may use
      */
     @SuppressWarnings("synthetic-access")
     public final double[] getGranularities(final Dimension dimension)
     {
         return dimension.getAxis(this).granularities;
     }
 
     /**
      * Returns the selected granularity that a linked plot should use.
      * @param dimension Dimension; space or time
      * @return double; granularity that a linked plot should use
      */
     @SuppressWarnings("synthetic-access")
     public final double getGranularity(final Dimension dimension)
     {
         return dimension.getAxis(this).granularity;
     }
 
     /**
      * Called by {@code AbstractContourPlot} to update the time. This will invalidate the plot triggering a redraw.
      * @param updateTime Time; current time
      */
     @SuppressWarnings("synthetic-access")
     final synchronized void increaseTime(final Time updateTime)
     {
         if (updateTime.si > this.timeAxis.maxValue)
         {
             this.timeAxis.setMaxValue(updateTime.si);
             for (AbstractContourPlot<?> plot : this.plots)
             {
                 plot.setUpperDomainBound(updateTime.si);
             }
         }
         if (this.toTime == null || updateTime.si > this.toTime.si) // null at initialization
         {
             invalidate(updateTime);
         }
     }
 
     /**
      * Sets the granularity of the plot. This will invalidate the plot triggering a redraw.
      * @param dimension Dimension; space or time
      * @param granularity double; granularity in space or time (SI unit)
      */
     public final synchronized void setGranularity(final Dimension dimension, final double granularity)
     {
         if (dimension.equals(Dimension.DISTANCE))
         {
             this.desiredSpaceGranularity = granularity;
             for (AbstractContourPlot<?> contourPlot : ContourDataSource.this.plots)
             {
                 contourPlot.setSpaceGranularity(granularity);
             }
         }
         else
         {
             this.desiredTimeGranularity = granularity;
             for (AbstractContourPlot<?> contourPlot : ContourDataSource.this.plots)
             {
                 contourPlot.setUpdateInterval(Duration.instantiateSI(granularity));
                 contourPlot.setTimeGranularity(granularity);
             }
         }
         invalidate(null);
     }
 
     /**
      * Sets bi-linear interpolation enabled or disabled. This will invalidate the plot triggering a redraw.
      * @param interpolate boolean; whether to enable interpolation
      */
     @SuppressWarnings("synthetic-access")
     public final void setInterpolate(final boolean interpolate)
     {
         if (this.timeAxis.interpolate != interpolate)
         {
             synchronized (this)
             {
                 this.timeAxis.setInterpolate(interpolate);
                 this.spaceAxis.setInterpolate(interpolate);
                 for (AbstractContourPlot<?> contourPlot : ContourDataSource.this.plots)
                 {
                     contourPlot.setInterpolation(interpolate);
                 }
                 invalidate(null);
             }
         }
     }
 
     /**
      * Sets the adaptive smoothing enabled or disabled. This will invalidate the plot triggering a redraw.
      * @param smooth boolean; whether to smooth the plor
      */
     public final void setSmooth(final boolean smooth)
     {
         if (this.smooth != smooth)
         {
             synchronized (this)
             {
                 this.smooth = smooth;
                 invalidate(null);
             }
         }
     }
 
     // ************************
     // *** UPDATING METHODS ***
     // ************************
 
     /**
      * Each method that changes a setting such that the plot is no longer valid, should call this method after the setting was
      * changed. If time is updated (increased), it should be given as input in to this method. The given time <i>should</i> be
      * {@code null} if the plot is not valid for any other reason. In this case a full redo is initiated.
      * <p>
      * Every method calling this method should be {@code synchronized}, at least for the part where the setting is changed and
      * this method is called. This method will in all cases add an update request to the updater, working in another thread. It
      * will invoke method {@code update()}. That method utilizes a synchronized block to obtain all synchronization sensitive
      * data, before starting the actual work.
      * @param t Time; time up to which to show data
      */
     private synchronized void invalidate(final Time t)
     {
         if (t != null)
         {
             this.toTime = t;
         }
         else
         {
             this.redo = true;
         }
         if (this.toTime != null) // null at initialization
         {
             // either a later time was set, or time was null and a redo is required (will be picked up through the redo field)
             // note that we cannot set {@code null}, hence we set the current to time, which may or may not have just changed
             this.graphUpdater.offer(this.toTime);
         }
     }
 
     /**
      * Heart of the data pool. This method is invoked regularly by the "DataPool worker" thread, as scheduled in a queue through
      * planned updates at an interval, or by user action changing the plot appearance. No two invocations can happen at the same
      * time, as the "DataPool worker" thread executes this method before the next update request from the queue is considered.
      * <p>
      * This method regularly checks conditions that indicate the update should be interrupted as for example a setting has
      * changed and appearance should change. Whenever a new invalidation causes {@code redo = true}, this method can stop as the
      * full data needs to be recalculated. This can be set by any change of e.g. granularity or smoothing, during the update.
      * <p>
      * During the data recalculation, a later update time may also trigger this method to stop, while the next update will pick
      * up where this update left off. During the smoothing this method doesn't stop for an increased update time, as that will
      * leave a gap in the smoothed data. Note that smoothing either smoothes all data (when {@code redo = true}), or only the
      * last part that falls within the kernel.
      * @param t Time; time up to which to show data
      */
     @SuppressWarnings({"synthetic-access", "methodlength"})
     private void update(final Time t)
     {
         Throw.when(this.plots.isEmpty(), IllegalStateException.class, "ContourDataSource is used, but not by a contour plot!");
 
         if (t.si < this.toTime.si)
         {
             // skip this update as new updates were commanded, while this update was in the queue, and a previous was running
             return;
         }
 
         /**
          * This method is executed once at a time by the worker Thread. Many properties, such as the data, are maintained by
          * this method. Other properties, which other methods can change, are read first in a synchronized block, while those
          * methods are also synchronized.
          */
         boolean redo0;
         boolean smooth0;
         boolean interpolate0;
         double timeGranularity;
         double spaceGranularity;
         double[] spaceTicks;
         double[] timeTicks;
         int fromSpaceIndex = 0;
         int fromTimeIndex = 0;
         int toTimeIndex;
         double tFromEgtf = 0;
         int nFromEgtf = 0;
         synchronized (this)
         {
             // save local copies so commands given during this execution can change it for the next execution
             redo0 = this.redo;
             smooth0 = this.smooth;
             interpolate0 = this.timeAxis.interpolate;
             // timeTicks may be longer than the simulation time, so we use the time bin for the required time of data
             if (this.desiredTimeGranularity != null)
             {
                 this.timeAxis.setGranularity(this.desiredTimeGranularity);
                 this.desiredTimeGranularity = null;
             }
             if (this.desiredSpaceGranularity != null)
             {
                 this.spaceAxis.setGranularity(this.desiredSpaceGranularity);
                 this.desiredSpaceGranularity = null;
             }
             timeGranularity = this.timeAxis.granularity;
             spaceGranularity = this.spaceAxis.granularity;
             spaceTicks = this.spaceAxis.getTicks();
             timeTicks = this.timeAxis.getTicks();
             if (!redo0)
             {
                 // remember where we started, readyItems will be updated but we need to know where we started during the update
                 fromSpaceIndex = getSpaceBin(this.readyItems + 1);
                 fromTimeIndex = getTimeBin(this.readyItems + 1);
             }
             toTimeIndex = ((int) (t.si / timeGranularity)) - (interpolate0 ? 0 : 1);
             if (smooth0)
             {
                 // time of current bin - kernel size, get bin of that time, get time (middle) of that bin
                 tFromEgtf = this.timeAxis.getBinValue(redo0 ? 0 : this.timeAxis.getValueBin(
                         this.timeAxis.getBinValue(fromTimeIndex) - Math.max(TAU.si, timeGranularity / 2) * KERNEL_FACTOR));
                 nFromEgtf = this.timeAxis.getValueBin(tFromEgtf);
             }
             // starting execution, so reset redo trigger which any next command may set to true if needed
             this.redo = false;
         }
 
         // reset upon a redo
         if (redo0)
         {
             this.readyItems = -1;
 
             // init all data arrays
             int nSpace = spaceTicks.length - 1;
             int nTime = timeTicks.length - 1;
             this.distance = new float[nSpace][nTime];
             this.time = new float[nSpace][nTime];
             for (ContourDataType<?, ?> contourDataType : this.additionalData.keySet())
             {
                 this.additionalData.put(contourDataType, new float[nSpace][nTime]);
             }
 
             // setup the smoothing filter
             if (smooth0)
             {
                 // create the filter
                 this.egtf = new Egtf(C_CONG.si, this.cFree.si, DELTA_V.si, this.vc.si);
 
                 // create data source and its data streams for speed, distance traveled, time traveled, and additional
                 DataSource generic = this.egtf.getDataSource("generic");
                 generic.addStream(TypedQuantity.SPEED, Speed.instantiateSI(1.0), Speed.instantiateSI(1.0));
                 generic.addStreamSI(this.travelTimeQuantity, 1.0, 1.0);
                 generic.addStreamSI(this.travelDistanceQuantity, 1.0, 1.0);
                 this.speedStream = generic.getStream(TypedQuantity.SPEED);
                 this.travelTimeStream = generic.getStream(this.travelTimeQuantity);
                 this.travelDistanceStream = generic.getStream(this.travelDistanceQuantity);
                 for (ContourDataType<?, ?> contourDataType : this.additionalData.keySet())
                 {
                     this.additionalStreams.put(contourDataType, generic.addStreamSI(contourDataType.getQuantity(), 1.0, 1.0));
                 }
 
                 // in principle we use sigma and tau, unless the data is so rough, we need more (granularity / 2).
                 double tau2 = Math.max(TAU.si, timeGranularity / 2);
                 double sigma2 = Math.max(SIGMA.si, spaceGranularity / 2);
                 // for maximum space and time range, increase sigma and tau by KERNEL_FACTOR, beyond which both kernels diminish
                 this.egtf.setGaussKernelSI(sigma2 * KERNEL_FACTOR, tau2 * KERNEL_FACTOR, sigma2, tau2);
 
                 // add listener to provide a filter status update and to possibly stop the filter when the plot is invalidated
                 this.egtf.addListener(new EgtfListener()
                 {
                     /** {@inheritDoc} */
                     @Override
                     public void notifyProgress(final EgtfEvent event)
                     {
                         // check stop (explicit use of property, not locally stored value)
                         if (ContourDataSource.this.redo)
                         {
                             // plots need to be redone
                             event.interrupt(); // stop the EGTF
                         }
                     }
                 });
             }
         }
 
         // discard any data from smoothing if we are not smoothing
         if (!smooth0)
         {
             // free for garbage collector to remove the data
             this.egtf = null;
             this.speedStream = null;
             this.travelTimeStream = null;
             this.travelDistanceStream = null;
             this.additionalStreams.clear();
         }
 
         // ensure capacity
         for (int i = 0; i < this.distance.length; i++)
         {
             this.distance[i] = GraphUtil.ensureCapacity(this.distance[i], toTimeIndex + 1);
             this.time[i] = GraphUtil.ensureCapacity(this.time[i], toTimeIndex + 1);
             for (float[][] additional : this.additionalData.values())
             {
                 additional[i] = GraphUtil.ensureCapacity(additional[i], toTimeIndex + 1);
             }
         }
 
         // loop cells to update data
         for (int j = fromTimeIndex; j <= toTimeIndex; j++)
         {
             Time tFrom = Time.instantiateSI(timeTicks[j]);
             Time tTo = Time.instantiateSI(timeTicks[j + 1]);
 
             // we never filter time, time always spans the entire simulation, it will contain tFrom till tTo
 
             for (int i = fromSpaceIndex; i < spaceTicks.length - 1; i++)
             {
                 // when interpolating, set the first row and column to NaN so colors representing 0 do not mess up the edges
                 if ((j == 0 || i == 0) && interpolate0)
                 {
                     this.distance[i][j] = Float.NaN;
                     this.time[i][j] = Float.NaN;
                     this.readyItems++;
                     continue;
                 }
 
                 // only first loop with offset, later in time, none of the space was done in the previous update
                 fromSpaceIndex = 0;
                 Length xFrom = Length.instantiateSI(spaceTicks[i]);
                 Length xTo = Length.instantiateSI(Math.min(spaceTicks[i + 1], this.path.getTotalLength().si));
 
                 // init cell data
                 double totalDistance = 0.0;
                 double totalTime = 0.0;
                 Map<ContourDataType<?, ?>, Object> additionalIntermediate = new LinkedHashMap<>();
                 for (ContourDataType<?, ?> contourDataType : this.additionalData.keySet())
                 {
                     additionalIntermediate.put(contourDataType, contourDataType.identity());
                 }
 
                 // aggregate series in cell
                 for (int series = 0; series < this.path.getNumberOfSeries(); series++)
                 {
                     // obtain trajectories
                     List<TrajectoryGroup<?>> trajectories = new ArrayList<>();
                     for (Section<? extends LaneData<?>> section : getPath().getSections())
                     {
                         TrajectoryGroup<?> trajectoryGroup = this.samplerData.getTrajectoryGroup(section.getSource(series));
                         if (null == trajectoryGroup)
                         {
                             CategoryLogger.always().error("trajectoryGroup {} is null", series);
                         }
                         trajectories.add(trajectoryGroup);
                     }
 
                     // filter groups (lanes) that overlap with section i
                     List<TrajectoryGroup<?>> included = new ArrayList<>();
                     List<Length> xStart = new ArrayList<>();
                     List<Length> xEnd = new ArrayList<>();
                     for (int k = 0; k < trajectories.size(); k++)
                     {
                         TrajectoryGroup<?> trajectoryGroup = trajectories.get(k);
                         LaneData<?> lane = trajectoryGroup.getLane();
                         Length startDistance = this.path.getStartDistance(this.path.get(k));
                         if (startDistance.si + this.path.get(k).length().si > spaceTicks[i]
                                 && startDistance.si < spaceTicks[i + 1])
                         {
                             included.add(trajectoryGroup);
                             double scale = this.path.get(k).length().si / lane.getLength().si;
                             // divide by scale, so we go from base length to section length
                             xStart.add(Length.max(xFrom.minus(startDistance).divide(scale), Length.ZERO));
                             xEnd.add(Length.min(xTo.minus(startDistance).divide(scale), trajectoryGroup.getLane().getLength()));
                         }
                     }
 
                     // accumulate distance and time of trajectories
                     for (int k = 0; k < included.size(); k++)
                     {
                         TrajectoryGroup<?> trajectoryGroup = included.get(k);
                         for (Trajectory<?> trajectory : trajectoryGroup.getTrajectories())
                         {
                             // for optimal operations, we first do quick-reject based on time, as by far most trajectories
                             // during the entire time span of simulation will not apply to a particular cell in space-time
                             if (GraphUtil.considerTrajectory(trajectory, tFrom, tTo))
                             {
                                 // again for optimal operations, we use a space-time view only (we don't need more)
                                 SpaceTimeView spaceTimeView;
                                 try
                                 {
                                     spaceTimeView = trajectory.getSpaceTimeView(xStart.get(k), xEnd.get(k), tFrom, tTo);
                                 }
                                 catch (IllegalArgumentException exception)
                                 {
                                     CategoryLogger.always().debug(exception,
                                             "Unable to generate space-time view from x = {} to {} and t = {} to {}.",
                                             xStart.get(k), xEnd.get(k), tFrom, tTo);
                                     continue;
                                 }
                                 totalDistance += spaceTimeView.getDistance().si;
                                 totalTime += spaceTimeView.getTime().si;
                             }
                         }
                     }
 
                     // loop and set any additional data
                     for (ContourDataType<?, ?> contourDataType : this.additionalData.keySet())
                     {
                         addAdditional(additionalIntermediate, contourDataType, included, xStart, xEnd, tFrom, tTo);
                     }
 
                 }
 
                 // scale values to the full size of a cell on a single lane, so the EGTF is interpolating comparable values
                 double norm = spaceGranularity / (xTo.si - xFrom.si) / this.path.getNumberOfSeries();
                 totalDistance *= norm;
                 totalTime *= norm;
                 this.distance[i][j] = (float) totalDistance;
                 this.time[i][j] = (float) totalTime;
                 for (ContourDataType<?, ?> contourDataType : this.additionalData.keySet())
                 {
                     this.additionalData.get(contourDataType)[i][j] =
                             finalizeAdditional(additionalIntermediate, contourDataType);
                 }
 
                 // add data to EGTF (yes it's a copy, but our local data will be overwritten with smoothed data later)
                 if (smooth0)
                 {
                     // center of cell
                     double xDat = (xFrom.si + xTo.si) / 2.0;
                     double tDat = (tFrom.si + tTo.si) / 2.0;
                     // speed data is implicit as totalDistance/totalTime, but the EGTF needs it explicitly
                     this.egtf.addPointDataSI(this.speedStream, xDat, tDat, totalDistance / totalTime);
                     this.egtf.addPointDataSI(this.travelDistanceStream, xDat, tDat, totalDistance);
                     this.egtf.addPointDataSI(this.travelTimeStream, xDat, tDat, totalTime);
                     for (ContourDataType<?, ?> contourDataType : this.additionalStreams.keySet())
                     {
                         ContourDataSource.this.egtf.addPointDataSI(
                                 ContourDataSource.this.additionalStreams.get(contourDataType), xDat, tDat,
                                 this.additionalData.get(contourDataType)[i][j]);
                     }
                 }
 
                 // check stop (explicit use of properties, not locally stored values)
                 if (this.redo)
                 {
                     // plots need to be redone, or time has increased meaning that a next call may continue further just as well
                     return;
                 }
 
                 // one more item is ready for plotting
                 this.readyItems++;
             }
 
             // notify changes for every time slice
             this.plots.forEach((plot) -> plot.notifyPlotChange());
         }
 
         // smooth all data that is as old as our kernel includes (or all data on a redo)
         if (smooth0)
         {
             Set<Quantity<?, ?>> quantities = new LinkedHashSet<>();
             quantities.add(this.travelDistanceQuantity);
             quantities.add(this.travelTimeQuantity);
             for (ContourDataType<?, ?> contourDataType : this.additionalData.keySet())
             {
                 quantities.add(contourDataType.getQuantity());
             }
             Filter filter = this.egtf.filterFastSI(spaceTicks[0] + 0.5 * spaceGranularity, spaceGranularity,
                     spaceTicks[0] + (-1.5 + spaceTicks.length) * spaceGranularity, tFromEgtf, timeGranularity, t.si,
                     quantities.toArray(new Quantity<?, ?>[quantities.size()]));
             if (filter != null) // null if interrupted
             {
                 overwriteSmoothed(this.distance, nFromEgtf, filter.getSI(this.travelDistanceQuantity));
                 overwriteSmoothed(this.time, nFromEgtf, filter.getSI(this.travelTimeQuantity));
                 for (ContourDataType<?, ?> contourDataType : this.additionalData.keySet())
                 {
                     overwriteSmoothed(this.additionalData.get(contourDataType), nFromEgtf,
                             filter.getSI(contourDataType.getQuantity()));
                 }
                 this.plots.forEach((plot) -> plot.notifyPlotChange());
             }
         }
     }
 
     /**
      * Add additional data to stored intermediate result.
      * @param additionalIntermediate Map&lt;ContourDataType&lt;?, ?&gt;, Object&gt;; intermediate storage map
      * @param contourDataType ContourDataType&lt;?, ?&gt;; additional data type
      * @param included List&lt;TrajectoryGroup&lt;?&gt;&gt;; trajectories
      * @param xStart List&lt;Length&gt;; start distance per trajectory group
      * @param xEnd List&lt;Length&gt;; end distance per trajectory group
      * @param tFrom Time; start time
      * @param tTo Time; end time
      * @param <I> intermediate data type
      */
     @SuppressWarnings("unchecked")
     private <I> void addAdditional(final Map<ContourDataType<?, ?>, Object> additionalIntermediate,
             final ContourDataType<?, ?> contourDataType, final List<TrajectoryGroup<?>> included, final List<Length> xStart,
             final List<Length> xEnd, final Time tFrom, final Time tTo)
     {
         additionalIntermediate.put(contourDataType, ((ContourDataType<?, I>) contourDataType)
                 .processSeries((I) additionalIntermediate.get(contourDataType), included, xStart, xEnd, tFrom, tTo));
     }
 
     /**
      * Stores a finalized result for additional data.
      * @param additionalIntermediate Map&lt;ContourDataType&lt;?, ?&gt;, Object&gt;; intermediate storage map
      * @param contourDataType ContourDataType&lt;?, ?&gt;; additional data type
      * @return float; finalized results for a cell
      * @param <I> intermediate data type
      */
     @SuppressWarnings("unchecked")
     private <I> float finalizeAdditional(final Map<ContourDataType<?, ?>, Object> additionalIntermediate,
             final ContourDataType<?, ?> contourDataType)
     {
         return ((ContourDataType<?, I>) contourDataType).finalize((I) additionalIntermediate.get(contourDataType)).floatValue();
     }
 
     /**
      * Helper method to fill smoothed data in to raw data.
      * @param raw float[][]; the raw unsmoothed data
      * @param rawCol int; column from which onward to fill smoothed data in to the raw data which is used for plotting
      * @param smoothed double[][]; smoothed data returned by {@code EGTF}
      */
     private void overwriteSmoothed(final float[][] raw, final int rawCol, final double[][] smoothed)
     {
         for (int i = 0; i < raw.length; i++)
         {
             // can't use System.arraycopy due to float vs double
             for (int j = 0; j < smoothed[i].length; j++)
             {
                 raw[i][j + rawCol] = (float) smoothed[i][j];
             }
         }
     }
 
     // ******************************
     // *** DATA RETRIEVAL METHODS ***
     // ******************************
 
     /**
      * Returns the speed of the cell pertaining to plot item.
      * @param item int; plot item
      * @return double; speed of the cell, calculated as 'total distance' / 'total space'.
      */
     public double getSpeed(final int item)
     {
         if (item > this.readyItems)
         {
             return Double.NaN;
         }
         return getTotalDistance(item) / getTotalTime(item);
     }
 
     /**
      * Returns the total distance traveled in the cell pertaining to plot item.
      * @param item int; plot item
      * @return double; total distance traveled in the cell
      */
     public double getTotalDistance(final int item)
     {
         if (item > this.readyItems)
         {
             return Double.NaN;
         }
         return this.distance[getSpaceBin(item)][getTimeBin(item)];
     }
 
     /**
      * Returns the total time traveled in the cell pertaining to plot item.
      * @param item int; plot item
      * @return double; total time traveled in the cell
      */
     public double getTotalTime(final int item)
     {
         if (item > this.readyItems)
         {
             return Double.NaN;
         }
         return this.time[getSpaceBin(item)][getTimeBin(item)];
     }
 
     /**
      * Returns data of the given {@code ContourDataType} for a specific item.
      * @param item int; plot item
      * @param contourDataType ContourDataType&lt;?, ?&gt;; contour data type
      * @return data of the given {@code ContourDataType} for a specific item
      */
     public double get(final int item, final ContourDataType<?, ?> contourDataType)
     {
         if (item > this.readyItems)
         {
             return Double.NaN;
         }
         return this.additionalData.get(contourDataType)[getSpaceBin(item)][getTimeBin(item)];
     }
 
     /**
      * Returns the time bin number of the item.
      * @param item int; item number
      * @return int; time bin number of the item
      */
     private int getTimeBin(final int item)
     {
         Throw.when(item < 0 || item >= this.spaceAxis.getBinCount() * this.timeAxis.getBinCount(),
                 IndexOutOfBoundsException.class, "Item out of range");
         return item / this.spaceAxis.getBinCount();
     }
 
     /**
      * Returns the space bin number of the item.
      * @param item int; item number
      * @return int; space bin number of the item
      */
     private int getSpaceBin(final int item)
     {
         return item % this.spaceAxis.getBinCount();
     }
 
     // **********************
     // *** HELPER CLASSES ***
     // **********************
 
     /**
      * Enum to refer to either the distance or time axis.
      * <p>
      * Copyright (c) 2013-2024 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved.
      * <br>
      * BSD-style license. See <a href="https://opentrafficsim.org/docs/license.html">OpenTrafficSim License</a>.
      * </p>
      * @author <a href="https://github.com/averbraeck">Alexander Verbraeck</a>
      * @author <a href="https://tudelft.nl/staff/p.knoppers-1">Peter Knoppers</a>
      * @author <a href="https://github.com/wjschakel">Wouter Schakel</a>
      */
     public enum Dimension
     {
         /** Distance axis. */
         DISTANCE
         {
             /** {@inheritDoc} */
             @Override
             protected Axis getAxis(final ContourDataSource dataPool)
             {
                 return dataPool.spaceAxis;
             }
         },
 
         /** Time axis. */
         TIME
         {
             /** {@inheritDoc} */
             @Override
             protected Axis getAxis(final ContourDataSource dataPool)
             {
                 return dataPool.timeAxis;
             }
         };
 
         /**
          * Returns the {@code Axis} object.
          * @param dataPool ContourDataSource; data pool
          * @return Axis; axis
          */
         protected abstract Axis getAxis(ContourDataSource dataPool);
     }
 
     /**
      * Class to store and determine axis information such as granularity, ticks, and range.
      * <p>
      * Copyright (c) 2013-2024 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved.
      * <br>
      * BSD-style license. See <a href="https://opentrafficsim.org/docs/license.html">OpenTrafficSim License</a>.
      * </p>
      * @author <a href="https://github.com/averbraeck">Alexander Verbraeck</a>
      * @author <a href="https://tudelft.nl/staff/p.knoppers-1">Peter Knoppers</a>
      * @author <a href="https://github.com/wjschakel">Wouter Schakel</a>
      */
     static class Axis
     {
         /** Minimum value. */
         private final double minValue;
 
         /** Maximum value. */
         private double maxValue;
 
         /** Selected granularity. */
         private double granularity;
 
         /** Possible granularities. */
         private final double[] granularities;
 
         /** Whether the data pool is set to interpolate. */
         private boolean interpolate = true;
 
         /** Tick values. */
         private double[] ticks;
 
         /**
          * Constructor.
          * @param minValue double; minimum value
          * @param maxValue double; maximum value
          * @param granularity double; initial granularity
          * @param granularities double[]; possible granularities
          */
         Axis(final double minValue, final double maxValue, final double granularity, final double[] granularities)
         {
             this.minValue = minValue;
             this.maxValue = maxValue;
             this.granularity = granularity;
             this.granularities = granularities;
         }
 
         /**
          * Sets the maximum value.
          * @param maxValue double; maximum value
          */
         void setMaxValue(final double maxValue)
         {
             if (this.maxValue != maxValue)
             {
                 this.maxValue = maxValue;
                 this.ticks = null;
             }
         }
 
         /**
          * Sets the granularity.
          * @param granularity double; granularity
          */
         void setGranularity(final double granularity)
         {
             if (this.granularity != granularity)
             {
                 this.granularity = granularity;
                 this.ticks = null;
             }
         }
 
         /**
          * Returns the ticks, which are calculated if needed.
          * @return double[]; ticks
          */
         double[] getTicks()
         {
             if (this.ticks == null)
             {
                 int n = getBinCount() + 1;
                 this.ticks = new double[n];
                 int di = this.interpolate ? 1 : 0;
                 for (int i = 0; i < n; i++)
                 {
                     if (i == n - 1)
                     {
                         this.ticks[i] = Math.min((i - di) * this.granularity, this.maxValue);
                     }
                     else
                     {
                         this.ticks[i] = (i - di) * this.granularity;
                     }
                 }
             }
             return this.ticks;
         }
 
         /**
          * Calculates the number of bins.
          * @return int; number of bins
          */
         int getBinCount()
         {
             return (int) Math.ceil((this.maxValue - this.minValue) / this.granularity) + (this.interpolate ? 1 : 0);
         }
 
         /**
          * Calculates the center value of a bin.
          * @param bin int; bin number
          * @return double; center value of the bin
          */
         double getBinValue(final int bin)
         {
             return this.minValue + (0.5 + bin - (this.interpolate ? 1 : 0)) * this.granularity;
         }
 
         /**
          * Looks up the bin number of the value.
          * @param value double; value
          * @return int; bin number
          */
         int getValueBin(final double value)
         {
             getTicks();
             if (value > this.ticks[this.ticks.length - 1])
             {
                 return this.ticks.length - 1;
             }
             int i = 0;
             while (i < this.ticks.length - 1 && this.ticks[i + 1] < value + 1e-9)
             {
                 i++;
             }
             return i;
         }
 
         /**
          * Sets interpolation, important is it required the data to have an additional row or column.
          * @param interpolate boolean; interpolation
          */
         void setInterpolate(final boolean interpolate)
         {
             if (this.interpolate != interpolate)
             {
                 this.interpolate = interpolate;
                 this.ticks = null;
             }
         }
 
         /**
          * Retrieve the interpolate flag.
          * @return boolean; true if interpolation is on; false if interpolation is off
          */
         public boolean isInterpolate()
         {
             return this.interpolate;
         }
 
         /** {@inheritDoc} */
         @Override
         public String toString()
         {
             return "Axis [minValue=" + this.minValue + ", maxValue=" + this.maxValue + ", granularity=" + this.granularity
                     + ", granularities=" + Arrays.toString(this.granularities) + ", interpolate=" + this.interpolate
                     + ", ticks=" + Arrays.toString(this.ticks) + "]";
         }
 
     }
 
     /**
      * Interface for data types of which a contour plot can be made. Using this class, the data pool can determine and store
      * cell values for a variable set of additional data types (besides total distance, total time and speed).
      * <p>
      * Copyright (c) 2013-2024 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved.
      * <br>
      * BSD-style license. See <a href="https://opentrafficsim.org/docs/license.html">OpenTrafficSim License</a>.
      * </p>
      * @author <a href="https://github.com/averbraeck">Alexander Verbraeck</a>
      * @author <a href="https://tudelft.nl/staff/p.knoppers-1">Peter Knoppers</a>
      * @author <a href="https://github.com/wjschakel">Wouter Schakel</a>
      * @param <Z> value type
      * @param <I> intermediate data type
      */
     public interface ContourDataType<Z extends Number, I>
     {
         /**
          * Returns the initial value for intermediate result.
          * @return I, initial intermediate value
          */
         I identity();
 
         /**
          * Calculate value from provided trajectories that apply to a single grid cell on a single series (lane).
          * @param intermediate I; intermediate value of previous series, starts as the identity
          * @param trajectories List&lt;TrajectoryGroup&lt;?&gt;&gt;; trajectories, all groups overlap the requested space-time
          * @param xFrom List&lt;Length&gt;; start location of cell on the section
          * @param xTo List&lt;Length&gt;; end location of cell on the section.
          * @param tFrom Time; start time of cell
          * @param tTo Time; end time of cell
          * @return I; intermediate value
          */
         I processSeries(I intermediate, List<TrajectoryGroup<?>> trajectories, List<Length> xFrom, List<Length> xTo, Time tFrom,
                 Time tTo);
 
         /**
          * Returns the final value of the intermediate result after all lanes.
          * @param intermediate I; intermediate result after all lanes
          * @return Z; final value
          */
         Z finalize(I intermediate);
 
         /**
          * Returns the quantity that is being plotted on the z-axis for the EGTF filter.
          * @return Quantity&lt;Z, ?&gt;; quantity that is being plotted on the z-axis for the EGTF filter
          */
         Quantity<Z, ?> getQuantity();
     }
 
     /** {@inheritDoc} */
     @Override
     public String toString()
     {
         return "ContourDataSource [samplerData=" + this.samplerData + ", updateInterval=" + this.updateInterval + ", delay="
                 + this.delay + ", path=" + this.path + ", spaceAxis=" + this.spaceAxis + ", timeAxis=" + this.timeAxis
                 + ", plots=" + this.plots + ", distance=" + Arrays.toString(this.distance) + ", time="
                 + Arrays.toString(this.time) + ", additionalData=" + this.additionalData + ", smooth=" + this.smooth
                 + ", cFree=" + this.cFree + ", vc=" + this.vc + ", egtf=" + this.egtf + ", speedStream=" + this.speedStream
                 + ", travelTimeStream=" + this.travelTimeStream + ", travelDistanceStream=" + this.travelDistanceStream
                 + ", travelTimeQuantity=" + this.travelTimeQuantity + ", travelDistanceQuantity=" + this.travelDistanceQuantity
                 + ", additionalStreams=" + this.additionalStreams + ", graphUpdater=" + this.graphUpdater + ", redo="
                 + this.redo + ", toTime=" + this.toTime + ", readyItems=" + this.readyItems + ", desiredSpaceGranularity="
                 + this.desiredSpaceGranularity + ", desiredTimeGranularity=" + this.desiredTimeGranularity + "]";
     }
 
 }