plot散点图怎么和chart.js

Question

I am trying to figure out how to plot a scatter graph with chart.js the data I am trying to plot is randomly generated where dates is a list of datetime.now() objects and prices is a list of float numbers

dates = [datetime.now().strftime("%Y-%m-%d")  for i in range(10)]

var dates_ = {{dates|tojson}}
var prices_ = {{prices|tojson}}
function parse_data(dates , prices)
{
    console.log(dates.length , prices.length)
    var tmp = [];
    for (let i = 0; i < dates.length; i++)
    {
        var x;
        var y;
        tmp[i] = {x: dates.at(i), y: prices.at(i)};
    }
    return tmp;
}
var data_ = parse_data(dates_, prices_);

var chart = new Chart(ctx, {
    type: 'scatter',
    data: {
        datasets: [{
        lablel: "some_data",
        data: data_}]
});

converting the dates to float numbers does the job but it shows the dates as number and it is not that good looking

Answer 1

You can define your x-axis as follows

x: {      
  type: 'time',
  time: {
    parser: 'YYYY-M-D',
    unit: 'day',
    displayFormats: {
      day: 'D MMM YYYY'
    },
    tooltipFormat: 'D MMM YYYY'
  }
}

Further information can be found at the Chart.js documentation here and in the Chart.js samples here .

Note that I use chartjs-adapter-moment together with moment to make this work. The formats for parsing and displaying time values as desired can be found here .

Please take a look at your amended code and see how it works.

 var test = [ { x: "2022-1-8", y: 950 }, { x: "2022-1-9", y: 1100 }, { x: "2022-1-10", y: 990 }, { x: "2022-1-12", y: 1250 }, { x: "2022-1-13", y: 1050 } ]; var chart = new Chart('chart-line', { type: 'scatter', data: { datasets: [{ data: test, label: 'buys', borderColor: "#3e95cd" }] }, options: { responsive: false, scales: { x: { type: 'time', time: { parser: 'YYYY-M-D', unit: 'day', displayFormats: { day: 'D MMM YYYY' }, tooltipFormat: 'D MMM YYYY' } } } } });

 <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.7.0/chart.min.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment-with-locales.js"></script> <script src="https://cdn.jsdelivr.net/npm/chartjs-adapter-moment@1.0.0"></script> <canvas id="chart-line" height="200"></canvas>

Answer 2

The scatter chart uses a line chart internally but changes it so the showLine property becomes false and both axis are set to linear.

So you can just set the showLine property to false in your dataset and use a line chart.

Answer 3

 const data = { labels: ["JAN", "FEB", "MAR", "APR", "MAY", "JUN", "JUL", "AUG", "SEP", "OCT", "NOV", "DEC"], datasets: [{ label: 'Dataset 1', data: [{x:1, y:12}, {x:2, y:3}, {x:3, y:2}, {x:4, y:1}, {x:5, y:8}, {x:6, y:8}, {x:7, y:2}, {x:8, y:2}, {x:9, y:3}, {x:10, y:5}, {x:11, y:7}, {x:12, y:1}] }] } const config = { type: 'scatter', data, options: { responsive: true, maintainAspectRatio: false, }, } const $canvas = document.getElementById('chart') const chart = new Chart($canvas, config)

 <div class="wrapper" style="width: 98vw; height:180px"> <canvas id="chart"></canvas> </div> <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.9.1/chart.min.js"></script>