JFreechart 实时组合图 - 如果未收到数据点，则渲染步骤子图的前一个值
我在 JFreechart 中有一个组合图，由 4 个具有公共时域轴的时间序列图表组成。
子图的数据以不同的速率到达。 例如，我可能每几毫秒收到一次价格变化事件，每分钟收到一次仓位变化。 我目前正在使用 XYStepRenderer 渲染这些系列以生成步骤图。
我希望能够做这样的事情：
- 在时间 T 收到价格点并将其绘制在图表上
- 在时间 T 没有收到持仓图表的数据，因此我们假设该值没有改变，并且呈现先前的仓位值 - 即水平延伸阶梯线
- 在时间 T+1 接收并绘制位置点 更改阶梯图
- 在时间 T+1 没有接收到价格点，因此绘制了先前的价格
是否有任何价格 点在 JFreechart 中执行此操作的简单方法？ 目前我有一个有效的实现，但这不能处理呈现假设值。
我最初的想法是更改数据模型，以便我可以快速找到以前的值，并更改调用以告诉每个子图在收到任何图的事件时进行绘制。
I have a combined plot in JFreechart consisting of 4 timeseries charts with a common time domain axis.
The data for the subplots arrives at different rates. For example I may receive a price change event every couple of miliseconds and a position change every minute. I'm currently rendering these series with the XYStepRenderer to produce a step charts.
I'd like to be able to do something like this:
- A Price point is received at time T and is plotted on chart
- No data has been received at time T for the position chart and so we assume that the value has not changed and the previous position value is rendered - i.e. extending the step line horizontally
- At time T+1 a position point is received and is plotted changing the step chart
- At time T+1 no price point has been received and so the previous price is plotted
Is there any easy way to do this in JFreechart? Currently I have a working implementation but this does not handle rendering the assumed values.
My initial thoughts have been around changing the data model so that I can quickly find the previous value and to change the calls to tell each subplot to draw when an event is received for any plot.
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我认为您需要缓冲传入的更改并应用规则集将更改转发到 JFreeChart（顺便说一句，对于实时工作并不真正建议这样做，但我发现对于低频更新来说它效果很好）。
我猜您有价格数据集和持仓数据集。 您的仓位和价格更新是否带有时间戳？ 如果没有，您将遇到按顺序接收这些数据并尝试将它们联系起来的问题（也许在某个时间窗口内到达的更新映射到同一时刻？）。 如果它们确实有时间戳，那么您可以在价格出现时派生一个新头寸（与旧头寸相同），然后在需要时替换它。
无论发生什么情况，我都会将图表更新与头寸/价格更新分离，以防万一您被头寸/价格变化淹没。 您不希望将其转化为必须立即丢弃的多个图表更新。
I think you'll need to buffer the incoming changes and apply a ruleset for forwarding changes onto JFreeChart (which is not really recommended for real-time work btw., but I've found that for low frequency updates it works well).
I'm guessing you have a dataset for the prices and a dataset for the positions. Do your position and price updates come in with a timestamp ? If not, you'll have the problem of receiving these sequentially and trying to tie them up (perhaps updates arriving within a certain timewindow map to the same time instant?). If they do have timestamps, then you can derive a new position (same as the old position) when the price comes in, and then replace that if need be.
I would decouple the chart updating from the position/price updates whatever happens, just in case you get swamped with position/price changes. You don't want that to translate into multiple chart updates that you're going to have to throw away immediately.