如何仅显示“过去 24 小时"?从“过去 72 小时

How to display only quot;last 24 hoursquot; from a quot;last 72 hoursquot; JFreeChart TimeSeries(如何仅显示“过去 24 小时?从“过去 72 小时开始JFreeChart 时间序列)

问题描述

我编写了这两行代码来使用 XYDataset 创建图表:

final XYDataset dataset = new TimeSeriesCollection(myInfo.getSeries());JFreeChart timechart = ChartFactory.createTimeSeriesChart(myInfo.getName()+ " CPU (last 72h)", "", "CPU %", dataset, false, false, false);

这些线条创建了这个漂亮的过去 72 小时"图表:

这就是我添加信息来构建这个图表的方式(这段代码可以运行多次):

SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd H:mm:ss");日期日期 = simpleDateFormat.parse(dateAsStringToParse);秒秒 = 新秒(日期)；myInfo.getSeries().addOrUpdate(second, maxValue);//maxValue 是一个整数

我想要一个(看似)简单的更改——将其删减"到最后 24 小时.我的意思是在图表中只看到最近的 24 小时，就像这样(图中是我使用相同技术制作的不同图表，但信息仅存在于最近 24 小时):

我查看了 API 并找不到合适的答案，因为我相信这应该有一些聪明而简单的解决方案.

而不是丢弃旧数据，建议

顺便说一句，请注意，自从提交补丁后，一些类已经移动:

import org.jfree.ui.ApplicationFrame;导入 org.jfree.ui.RefineryUtilities；

<块引用>

我不能只使用 setMaximumItemAge() 吗?

不是孤立的；addOrUpdate()，et al.，在通知侦听器之前调用 removeAgedItems(false).

我正在使用 Second.

Second 数据的三天，例如，将暗示 setMaximumItemAge(3 * 24 * 60 * 60).

我可能无法使用滑动窗口，因为我将图表保存为 JPEG.

您可以将所需的 firstItemIndex 作为参数传递给 SlidingXYDataset 构造函数；如果需要，您可以稍后通过 setFirstItemIndex() 更新索引.

I wrote these 2 lines of code to create a chart using an XYDataset:

final XYDataset dataset = new TimeSeriesCollection(myInfo.getSeries());
JFreeChart timechart = ChartFactory.createTimeSeriesChart(myInfo.getName()
    + " CPU (last 72h)", "", "CPU %", dataset, false, false, false);

These lines created this nice "last 72h" chart:

This is how I added the information to build this chart (this piece of code can run multiple times):

SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd H:mm:ss");
Date date = simpleDateFormat.parse(dateAsStringToParse);
Second second = new Second(date);
myInfo.getSeries().addOrUpdate(second, maxValue); // maxValue is an Integer

I want a (seemingly) simple alteration—to "cut" this only to the last 24 hours. I mean to see only the most "recent" 24 hours in the graph, like so (in the picture is a different chart I made using the same technique, but the information exists only for the last 24hrs):

I have looked through the API and could not find an appropriate answer, as I believe this should have some clever but simple solution.

Instead of discarding old data, as suggested here, it looks like you want to display a contiguous subset of the data, as if looking through a window. While SlidingCategoryDataset provides this feature for a CategoryDataset, there is no built-in solution for an XYDataset. SlidingXYDataset, seen here, maybe an alternative. In the variation of SliderDemo2 illustrated below, I've added three days of data to a single series with a one day window. I've retained the slider for easy review of earlier values.

static final int COUNT = 3 * 24 * 60;
public static final int WINDOW = 24 * 60;
public static final int FIRST = 2 * 24 * 60;
…
this.slider.setValue(FIRST);

As an aside, note that some classes have moved since the patch was submitted:

import org.jfree.ui.ApplicationFrame;
import org.jfree.ui.RefineryUtilities;

Can't I just use setMaximumItemAge()?

Not in isolation; addOrUpdate(), et al., calls removeAgedItems(false) before notifying listeners.

I am using Second.

Threes days of Second data, e.g., would imply setMaximumItemAge(3 * 24 * 60 * 60).

A sliding window might not be available to me since I am saving the chart as a JPEG.

You can pass the desired firstItemIndex as a parameter to the SlidingXYDataset constructor; you can update the index later via setFirstItemIndex() if needed.

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