JFreeChart：DynamicTimeSeries，周期为 n 毫秒

Question

我正在尝试定义一个接口，我想在其中绘制一些外部设备接收到的值。 这些值的接收频率可以通过接口设置。当然，情节的周期应该根据用户定义的周期而变化。 于是我开始定义如下图表：

int periodMs = 200;
MilliDTSC dataset = new MilliDTSC(1,100, new MultipleOfMillisecond(periodMs));
dataset.setTimeBase(new MultipleOfMillisecond(periodMs))
dataset.addSeries(zeroSeries()),0,"Zero data") // zeroSeries returs a series with values set to 0
JFreeChart chart = createChart(dataset) // create the chart and set ranges and legends
ChartPanel panel = new ChartPanel(panel);

MilliDTSC 是以下类，建议here：

public class MilliDTSC extends DynamicTimeSeriesCollection{
  public MilliDTSC(int nSeries, int nMoments, RegularTimePeriod timeSample){
    super(nSeries, nMoments, timeSample);
    if(timeSample instanceof Millisecond)
      this.pointsInTime = new Millisecond[nMoments]
    else if (timeSample instanceof MultipleOfMillisecond)
      this.pointsInTime = new MultipleOfMillisecond[nMoments]
  }
}

MultipleOfMillisecond 是以下类：

public class MultipleOfMilliseconds extends Millisecond{
  MulitpleOfMilliseconds(int periodMs){
    this.periodMs = periodMs
  }

  public RegularTimePeriod previous(){
    RegularTimePeriod result = null;
    if(getMillisecond() - periodMs >= FIRST_MILLISECOND_IN_SECOND)
      result = new Millisecond((int)getMillisecond - periodMs, getSecond());
    else{
      Second previous = (Second)getSecond().previous();
      if(previous!=null)
        result = new Millisecond((int)(getMillisecond() - periodMS + LAST_MILLISECOND_IN_SECOND + 1), previous);
    }
    return result;
  }
  // similar for next()
}

我通过以下方式将样本添加到系列中：

dataset.advanceTime();
dataset.appendData(newData);

我所期望的是，一旦我将周期固定为 200 毫秒，图表就会在 X 标签上报告或多或少 5 个时间值：

00:00:00.000 00:00:05.000 00:00:10.000 00:00:15.000 00:00:20.000

我预计每个“空间”中有 25 个样本。

相反，我对每个“空间”有 25 个样本，但图表在 X 标签上报告了以下值：

00:00:00.000 00:00:00.025 00:00:00.050 00:00:00.075 00:00:00.100

似乎周期是 1 毫秒，但我添加的样本非常 200 毫秒。

我该如何解决这个问题？ 如果我不清楚，请告诉我。 谢谢！！

Answer 1

我想是因为你有这个：

public class MultipleOfMilliseconds extends Millisecond
//                                          ^^^^^^^^^^^

这是true：

if(timeSample instanceof Millisecond)

如果你改变测试的顺序，你可能会有更好的运气：

if(timeSample instanceof MultipleOfMillisecond)
  this.pointsInTime = new MultipleOfMillisecond[nMoments];
else if (timeSample instanceof Millisecond)
  this.pointsInTime = new Millisecond[nMoments];

Answer 2

这是我实施的解决方案。 我只报告了我改变的方法。这是一个愚蠢的错误：D

public MilliDTSC(int nSeries, int nMoments, RegularTimePeriod timeSample) {
  super(nSeries, nMoments, timeSample);
  if(timeSample instanceof MultipleOfMillisecond){
    this.pointsInTime = new MultipleOfMillisecond[nMoments];
  }else if (timeSample instanceof Millisecond) {
    this.pointsInTime = new Millisecond[nMoments];
  } 
}

public class MultipleOfMillisecond extends Millisecond {

  private static final long serialVersionUID = 1L;
  private int periodMs = 100;

  public MultipleOfMillisecond(int periodMs){
    super();
    this.periodMs = periodMs;
  }

  public MultipleOfMillisecond(int periodMs, int millisecond, Second second){
    super(millisecond, second);
    this.periodMs = periodMs;
  }

  @Override
  public RegularTimePeriod next() {
    
    RegularTimePeriod result = null;
    if(getMillisecond() + periodMs <= LAST_MILLISECOND_IN_SECOND){
        result = new MultipleOfMillisecond( periodMs, (int)(getMillisecond() + periodMs), getSecond());
    }else{
        Second next = (Second)getSecond().next();
        if(next != null){
            result = new MultipleOfMillisecond(periodMs, (int)(getMillisecond() + periodMs - LAST_MILLISECOND_IN_SECOND - 1), next);
        }
    }
    return result;
    
  }

  @Override
  public RegularTimePeriod previous() {
    
    RegularTimePeriod result = null;
    if(getMillisecond() - periodMs >= FIRST_MILLISECOND_IN_SECOND){
        result = new MultipleOfMillisecond(periodMs, (int)getMillisecond() - periodMs, getSecond());
    }else{
        Second previous = (Second)getSecond().previous();
        if(previous != null){
            result = new MultipleOfMillisecond(periodMs, (int)(getMillisecond() - periodMs + LAST_MILLISECOND_IN_SECOND + 1), previous);
        }
    }
    return result;
    
  } 
}

现在我在 5 秒内有 10 个样本，我将周期设置为 500 毫秒

Answer 3

改为使用原始的MilliDTSC 和Millisecond，并调用advanceTime() 并在附加新数据之前根据需要附加旧数据。以 200 ms 为例，执行如下操作：

float[] newData = new float[1];
float[] oldData = new float[1];

@Override
public void actionPerformed(ActionEvent e) {
    newData[0] = randomValue();
    oldData[0] = newData[0];
    for (int i = 0; i < 200; i++) {
        dataset.advanceTime();
        dataset.appendData(oldData);
    }
    dataset.appendData(newData);
}

请注意，现在每秒有 5 个样本，间隔 200 毫秒。