如何在chartjs中绘制多个时间序列，其中每个时间序列都有不同的时间

本文介绍了如何在chartjs中绘制多个时间序列，其中每个时间序列都有不同的时间的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

例如，我有两个时间序列:

I have two time series for example:

s1: 2017-01-06 18:39:30 100 2017-01-07 18:39:28 101

和

s2: 2017-01-07 18:00:00 90 2017-01-08 18:00:00 105

我想在 Chartjs 图表中绘制这些，但是 Chartjs 似乎只需要一个 x 轴数组(或 Chartjs 术语中的标签).

I want to plot these in a Chartjs chart, however it seems that Chartjs only takes one x-axis array (or label in Chartjs terminology).

所以我的问题是绘制这两者的最佳方法是什么?

我的方法是编写一个函数(在 python 中，尽管语言对于这部分并不重要)，它遍历两个时间序列并创建 3 个新数组，其格式显然是 Chartjs 需要基于第一个示例此处:www.sitepoint/introduction-chart-js-2-0-six​​-examples/

My approach was to write a function (in python, although the language doesn't really matter for this part) that iterates through both time series and creates 3 new arrays which is in the format apparently Chartjs needs based off the 1st example here: www.sitepoint/introduction-chart-js-2-0-six-examples/

算法(在 sudo 代码中)如下所示:

The algorithm (in sudo code) goes like:

# inputs are initial time series s1 and s2 y1 = [] # to hold new s1 data values y2 = [] # to hold new s2 data values x = [] # to hold times # iterate through longest series s1 or s2 if s1[idx].time > s2[idx].time x.append(s1[idx].time) y1.append(s1[idx].data) # y2 appends the linear interpolation of # of closest y2 points if (s1[idx].time < s2[idx].time) x.append(s2[idx].time) # opposite of above. ie. swap y1<->y2, s1->s2 else # they have the same time x.append(s1[idx].time) y1.append(s1[idx].data) y2.append(s2[idx].data)

当数据用完较短的系列时，还有其他几个条件检查，但这是主要逻辑.之后我有 3 个数组，我现在可以通过一个时间/标签数组/x 轴和两个数据数组将它们添加到图表 js.然而，这似乎比我认为这个用例的常见程度要复杂得多.非常感谢任何帮助或建议.

There are a couple other conditional checks for when data runs out of the shorter series but that is the main logic. After which I have 3 arrays that I can now add to chart js via one time/label array/x-axis and two data arrays. However this seems WAY more complicated than it should be considering how common I assume this use case is. Any help or advice is greatly appreciated.

推荐答案

在 ChartJS 中，标签是一个 类别笛卡尔坐标轴.由于您在代码中提到了线性插值，我假设像 2017-01-06 18:39:30 这样的字符串不是类别，它们代表 x 轴的数值.所以我们需要通知 ChartJS x 轴上的字符串实际上是时间.我们在比例选项中执行此操作.

In ChartJS, label is a Category Cartesian Axis. Since you mentioned linear interpolation in your code, I assume the strings like 2017-01-06 18:39:30 are not categories, they represent the numeric values of the x-axis. So we need to inform ChartJS that the strings in the x axis are actually time. We do this in the scale options.

var s1 = { label: 's1', borderColor: 'blue', data: [ { x: '2017-01-06 18:39:30', y: 100 }, { x: '2017-01-07 18:39:28', y: 101 }, ] }; var s2 = { label: 's2', borderColor: 'red', data: [ { x: '2017-01-07 18:00:00', y: 90 }, { x: '2017-01-08 18:00:00', y: 105 }, ] }; var ctx = document.getElementById('myChart').getContext('2d'); var chart = new Chart(ctx, { type: 'line', data: { datasets: [s1, s2] }, options: { scales: { xAxes: [{ type: 'time' }] } } });

<script src="cdnjs.cloudflare/ajax/libs/moment.js/2.20.1/moment.min.js"></script> <script src="cdnjs.cloudflare/ajax/libs/Chart.js/2.7.1/Chart.min.js"></script> <canvas id="myChart"></canvas>

您可以在 Chart.js 文档中找到更多信息.

You can find more information in Chart.js documentation.