我是d3.js / javascript和Web导向编程的新手。
我的目标是通过websocket更新现有图表的值。
注意:在这个例子中,我已经有了一个javascript数组“var”,我需要添加通过websocket获取的新值,但不是必须的,数组“var”也可以为空。我的目标是绘制通过websocket ws接收到的数据。
我从python的websocket服务器(code1)中正确接收了值,但我仍然不明白如何在d3.js图形上绘制新元素。 我阅读了几篇关于更新模式示例的文档,例如https://bl.ocks.org/mbostock/3808218, 但仍然没有使用d3.js enter()/update()得到可行的解决方案。Code2是一个工作示例,以及用于websocket的javascript代码。我正确地获得了新数据并将其存储在变量“close”“when”中。是否有人能够帮助修改HTML代码以绘制新数据?谢谢您的帮助,问候。
Code1:工作的Python服务器websocket
#!/usr/bin/env python
import asyncio
import datetime
import random
import websockets
import numpy as np
import json
IP = '192.168.10.224'
PORT = 5678
def format_time():
t = datetime.datetime.now().time()
s = t.strftime('%H:%M:%S.%f')
return s[:-3]
async def time(websocket, path):
while True:
#now = datetime.datetime.utcnow().isoformat() + 'Z'
data = {'datetime': str(format_time()),
'ticker': 'ticker',
'value': str(random.randint(100,1000)),
'volume': str(random.randint(1,10))}
await websocket.send(json.dumps(data))
await asyncio.sleep(random.random() * 3)
start_server = websockets.serve(time, IP, PORT)
asyncio.get_event_loop().run_until_complete(start_server)
asyncio.get_event_loop().run_forever()
代码2: HTML页面 D3.js
<!DOCTYPE html>
<meta charset="utf-8">
<style> /* set the CSS */
.line {
fill: none;
stroke: steelblue;
stroke-width: 2px;
}
</style>
<body>
<!-- load the d3.js library -->
<script src="d3/d3.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
<script>
//working websocket get new data and print for debug purpose on javascript console
var ws = new WebSocket("ws://192.168.10.224:5678/")
ws.onmessage = function (event) {
var messages = document.getElementsByTagName('ul')[0],
message = document.createElement('li'),
content = document.createTextNode(event.data);
//console.log(typeof(event.data));
var obj = jQuery.parseJSON(event.data);
var close = obj.volume
var when = obj.datetime;
console.log(close,when);
};
// set the dimensions and margins of the graph
var margin = {top: 20, right: 20, bottom: 30, left: 50},
width = 960 - margin.left - margin.right,
height = 500 - margin.top - margin.bottom;
// parse the date / time
var parseTime = d3.timeParse("%H:%M:%S.%L");
// set the ranges
var x = d3.scaleTime().range([0, width]);
var y = d3.scaleLinear().range([height, 0]);
// define the line
var valueline = d3.line()
.x(function(d) { return x(d.date); })
.y(function(d) { return y(d.close); });
// append the svg obgect to the body of the page
// appends a 'group' element to 'svg'
// moves the 'group' element to the top left margin
var svg = d3.select("body").append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform",
"translate(" + margin.left + "," + margin.top + ")");
var data = [
{"date":"9:22:43.111","close":1.98},
{"date":"10:22:43.222","close":5.98},
{"date":"11:32:43.333","close":7.00},
{"date":"11:52:43.444","close":8.70},
{"date":"14:52:43.444","close":10.28},
{"date":"15:52:43.444","close":16.70},
{"date":"16:12:43.222","close":10.98},
{"date":"16:12:43.222","close":3.44},
{"date":"17:32:43.111","close":4.34},
];
//per ogni elemento converto la data
data.forEach(function(d) {
d.date = parseTime(d.date);
d.close = +d.close;
}
);
// Scale the range of the data
x.domain(d3.extent(data, function(d) { return d.date; }));
y.domain([0, d3.max(data, function(d) { return d.close; })]);
// Add the valueline path.
svg.append("path")
.data([data])
.attr("class", "line")
.attr("d", valueline);
// Add the X Axis
svg.append("g")
.attr("transform", "translate(0," + height + ")")
.call(d3.axisBottom(x)
.ticks(d3.timeMinute.every(30))
);
// Add the Y Axis
svg.append("g")
.call(d3.axisLeft(y));
</script>
</body>