Chart.js-使用JSON数据创建时间序列频率图表

Question

so recently I've been working on a web app that collects data from requests and I am trying to output the data into a graph based on frequency per hour/month etc.

So, I'm using Chart.js and have JSON data of dates and I'm trying to make a chart that shows the frequency of requests per hour, etc.

My data is just each request has a time stamp, so all I have is a bunch of time stamps in 2018-01-03 15:15:04 format. for example:

{'2018-01-03 15:15:04', '2018-01-04 06:32:45', '2018-01-04 23:32:45', '2018-02-23 01:24:32'}

except, I have hundreds of them. Just frequency per hour, month, etc is what I want.

Can anyone point me in the right direction? My two thoughts were this:

1. Just do the counting and parsing myself and come up with counts per hour and then just throw the data at the chart
2. Somehow use their built in functionality for time, which I am still a bit unclear about even after reading the docs.

thanks a ton, everyone!

Here's an example of what I would like: Chart example

Also, http://www.chartjs.org/samples/latest/scales/time/financial.html

Answer 1

Going with #1 on your list is your best bet. I wrote an example of how you can achieve it pretty easily.

First find the frequency (I did it by month/year) and add it to a Map . I used a map because the .keys() and .values() functions for a Map are returned in insertion order. A regular object cannot guarantee order.

Then, Chart.js can display those values pretty easily using spread syntax to turn the .keys() and .values() iterators into arrays.

 var a = ['2018-01-03 15:15:04', '2018-01-04 06:32:45', '2018-01-04 23:32:45', '2018-02-23 01:24:32', '2018-02-23 04:33:12', '2018-03-23 05:33:12', '2018-03-22 08:33:12', '2018-04-27 01:33:12']; var freqMap = new Map(); a.forEach(function(time) { var date = new Date(time); var monthName = date.toLocaleString("en-us", { month: "short" }); var key = monthName + "-" + date.getFullYear(); var count = freqMap.get(key) || 0; freqMap.set(key, ++count); }); var ctx = document.getElementById("myChart").getContext('2d'); var myLineChart = new Chart(ctx, { type: 'line', data: { labels: [...freqMap.keys()], datasets: [{ label: 'Requests per month', data: [...freqMap.values()] }], }, options: { elements: { line: { tension: 0 } }, scales: { yAxes: [{ ticks: { beginAtZero: true, stepSize: 1 } }] } } }); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.7.2/Chart.bundle.min.js"></script> <canvas id="myChart" width="400" height="400"></canvas>