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html - 烧瓶插座 | 使用 Flask Executor 或 ThreadPoolExecutor 创建的后台任务更新和绘制图表

问题描述

我目前正在尝试在更新数据框的结果或数据发生任何变化时成功绘制条形图。

设置：

确保重新启动机器以免遇到错误。

Python 代码- 保存在 D:\Projects\test_backgroundtask 中：

from flask import Flask, render_template, request
import pandas as pd
from flask_executor import Executor
import plotly
import plotly.graph_objs as go
from flask_socketio import SocketIO, emit
import json

global test_val
app = Flask(__name__)
socketio = SocketIO(app)
def create_plot(feature_importance):
    feature_importance=feature_importance.reset_index(drop=True)
    feature_importance=feature_importance.iloc[0:5]
    print(feature_importance)

    data = [
        go.Bar(
            x=feature_importance['Age'], # assign x as the dataframe column 'x'
            y=feature_importance['Name'], orientation='h'
        )
    ]

    graphJSON = json.dumps(data, cls=plotly.utils.PlotlyJSONEncoder)

    return graphJSON

@socketio.on("response")
def background_task_func():
    global test_val
    global plot
    socketio.sleep(10)
    data = {'Name': ['Tom', 'Joseph', 'Krish', 'John'], 'Age': [20, 21, 19, 18]}  
    test_val= pd.DataFrame(data)
    bar = create_plot(test_val)
    plot=bar
    if test_val.shape[0]>1:
        print(test_val)
        emit('response_output',plot ,broadcast=True)
        socketio.sleep(1)
        #return render_template('views/index_img_soc.html', plot=bar)
    
@app.route('/', methods=['GET'])
def index():
    global plot
    executor.submit(background_task_func)
    bar = create_plot(test_val)
    
    return render_template('views/index_img_soc.html', plot=bar)



if __name__ == "__main__":
    data ={'Name': [], 'Age': []}  
    test_val= pd.DataFrame(data)   
    executor = Executor(app)
    socketio.run(app)

Html 代码（保存在 D:\Projects\test_backgroundtask\template\views 中）：

<script src="https://cdn.plot.ly/plotly-latest.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.6/d3.min.js"></script>
<div class="chart" id="bargraph">

    <script src="//cdnjs.cloudflare.com/ajax/libs/socket.io/2.2.0/socket.io.js" integrity="sha256-yr4fRk/GU1ehYJPAs8P4JlTgu0Hdsp4ZKrx8bDEDC3I=" crossorigin="anonymous"></script>
        <script type="text/javascript" charset="utf-8">

            var socket = io().connect('http://127.0.0.1:5000');
            socket.emit('response')
            socket.on('response_output', function(receiving_data) {
              var graphs = {{plot | safe}};
              Plotly.plot('bargraph',graphs,{});
            });
    </script>
</div>

输出：

WebSocket transport not available. Install eventlet or gevent and gevent-websocket for improved performance.
 * Serving Flask app "flask_background_app_img_soc2" (lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
127.0.0.1 - - [14/Jul/2021 11:45:01] "GET / HTTP/1.1" 200 -
Empty DataFrame
Columns: [Name, Age]
Index: []
2c6e85bb23aa4c83af37bc005a08837b: Sending packet OPEN data {'sid': '2c6e85bb23aa4c83af37bc005a08837b', 'upgrades': [], 'pingTimeout': 60000, 'pingInterval': 25000}
2c6e85bb23aa4c83af37bc005a08837b: Sending packet MESSAGE data 0
127.0.0.1 - - [14/Jul/2021 11:45:03] "GET /socket.io/?EIO=3&transport=polling&t=NgaPyfS HTTP/1.1" 200 -
2c6e85bb23aa4c83af37bc005a08837b: Received packet MESSAGE data 2["response"]
received event "response" from 2c6e85bb23aa4c83af37bc005a08837b [/]
127.0.0.1 - - [14/Jul/2021 11:45:03] "POST /socket.io/?EIO=3&transport=polling&t=NgaPyf-&sid=2c6e85bb23aa4c83af37bc005a08837b HTTP/1.1" 200 -
     Name  Age
0     Tom   20
1  Joseph   21
2   Krish   19
3    John   18
     Name  Age
0     Tom   20
1  Joseph   21
2   Krish   19
3    John   18
emitting event "response_output" to all [/]
2c6e85bb23aa4c83af37bc005a08837b: Sending packet MESSAGE data 2["response_output","[{\"orientation\": \"h\", \"x\": [20, 21, 19, 18], \"y\": [\"Tom\", \"Joseph\", \"Krish\", \"John\"], \"type\": \"bar\"}]"]
127.0.0.1 - - [14/Jul/2021 11:45:13] "GET /socket.io/?EIO=3&transport=polling&t=NgaPyg0&sid=2c6e85bb23aa4c83af37bc005a08837b HTTP/1.1" 200 -
     Name  Age
0     Tom   20
1  Joseph   21
2   Krish   19
3    John   18
     Name  Age
0     Tom   20
1  Joseph   21
2   Krish   19
3    John   18
2c6e85bb23aa4c83af37bc005a08837b: Received packet PING data None
2c6e85bb23aa4c83af37bc005a08837b: Sending packet PONG data None
127.0.0.1 - - [14/Jul/2021 11:45:28] "GET /socket.io/?EIO=3&transport=polling&t=NgaP_9E&sid=2c6e85bb23aa4c83af37bc005a08837b HTTP/1.1" 200 -
127.0.0.1 - - [14/Jul/2021 11:45:28] "POST /socket.io/?EIO=3&transport=polling&t=NgaQ2md&sid=2c6e85bb23aa4c83af37bc005a08837b HTTP/1.1" 200 -
2c6e85bb23aa4c83af37bc005a08837b: Received packet PING data None
2c6e85bb23aa4c83af37bc005a08837b: Sending packet PONG data None
127.0.0.1 - - [14/Jul/2021 11:45:54] "GET /socket.io/?EIO=3&transport=polling&t=NgaQ2nA&sid=2c6e85bb23aa4c83af37bc005a08837b HTTP/1.1" 200 -
127.0.0.1 - - [14/Jul/2021 11:45:54] "POST /socket.io/?EIO=3&transport=polling&t=NgaQ93n&sid=2c6e85bb23aa4c83af37bc005a08837b HTTP/1.1" 200 -
2c6e85bb23aa4c83af37bc005a08837b: Received packet PING data None
2c6e85bb23aa4c83af37bc005a08837b: Sending packet PONG data None
127.0.0.1 - - [14/Jul/2021 11:46:20] "GET /socket.io/?EIO=3&transport=polling&t=NgaQ94a&sid=2c6e85bb23aa4c83af37bc005a08837b HTTP/1.1" 200 -
127.0.0.1 - - [14/Jul/2021 11:46:20] "POST /socket.io/?EIO=3&transport=polling&t=NgaQFPv&sid=2c6e85bb23aa4c83af37bc005a08837b HTTP/1.1" 200 -

即使数据框已更新，第一个输出也是如此。 第一个输出

重新加载页面后，页面为空白，然后显示正确的图表。 重新加载后

我想达到的目标：

  1. 更新数据框时自动显示条形图而无需重新加载页面。

标签： htmlpython-3.xchart.jsplotlyflask-socketio

解决方案

在function(receiving_data)html 页面中发现，使用了 variableplot而不是receiving_data. 变量在被调用plot时被初始化render_template。当通过套接字发出数据时，调用plotreturn 时不需要传递变量。render_template('views/index_img_soc.html', plot=bar)

请参阅下面的示例脚本，了解如何使用套接字向 html 脚本发送数据。

下面的脚本将自动更新条形图而无需重新加载页面。

使用 chart.js 而不是 plotly 的代码。与 plotly 相比，在 javascript 中绘制 chart.js 的示例要多得多。

更新的 Python 脚本：

import random
from flask import Flask, render_template, session, request
from flask_socketio import SocketIO
from flask_executor import Executor
import pandas as pd
import json
app = Flask(__name__)
app.config['SECRET_KEY'] = 'secret!'
socketio = SocketIO(app)
thread = None



@socketio.on("response_demo")
def background_task_func():
    """Example of how to send server generated events to clients."""

    socketio.sleep(5)
    print("send")
   
    data = {'Name': ['Tom', 'Joseph', 'Krish', 'John','Shadz'], 'Age': [20, 21, 19, 18,36]} 

    data_2= pd.DataFrame(data)
    
    df_json=data_2.to_json(orient='records')
    result = {"objects": json.loads(df_json)}
    socketio.emit('my_response',result, broadcast=True)

@app.route('/')
def index():
    executor.submit(background_task_func)
    return render_template('index_2.html')



if __name__ == '__main__':
    executor = Executor(app)
    socketio.run(app)

更新的 html 脚本：

<!DOCTYPE HTML>
<html>
<head>
    <title>Flask-SocketIO Test</title>
    <script type="text/javascript" src="//code.jquery.com/jquery-1.4.2.min.js"></script>
    <script type="text/javascript" src="//cdnjs.cloudflare.com/ajax/libs/socket.io/1.3.5/socket.io.min.js"></script>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.5.0/Chart.min.js"></script>
    <script src="//cdnjs.cloudflare.com/ajax/libs/socket.io/2.2.0/socket.io.js" integrity="sha256-yr4fRk/GU1ehYJPAs8P4JlTgu0Hdsp4ZKrx8bDEDC3I=" crossorigin="anonymous"></script>

</head>

<canvas id="myChart" width="100" height="100"></canvas>
    <script type="text/javascript" charset="utf-8">

// Chart.js Bar Chart
var ctx = document.getElementById("myChart");
var myChart = new Chart(ctx, {
    type: 'bar',
    data: {
        labels: ["Red", "Blue", "Yellow", "Green", "Purple"],
        datasets: [{
            data: [2, 2,2, 2,2],
            backgroundColor: [
                'rgba(255, 99, 132, 0.2)',
                'rgba(54, 162, 235, 0.2)',
                'rgba(255, 206, 86, 0.2)',
                'rgba(75, 192, 192, 0.2)',
                'rgba(153, 102, 255, 0.2)'
            ],
            borderColor: [
                'rgba(255,99,132,1)',
                'rgba(54, 162, 235, 1)',
                'rgba(255, 206, 86, 1)',
                'rgba(75, 192, 192, 1)',
                'rgba(153, 102, 255, 1)'
            ],
            borderWidth: 1
        }]
    },
    options: {
        scales: {
 
            yAxes: [{
                ticks: {
                    beginAtZero:true
                }
            }]
        }
    }
});


        $(document).ready(function() {

            var socket = io().connect('http://127.0.0.1:5000');
            socket.emit('response_demo')
            socket.on('my_response', function(obj) {
            for (var i=0; i < obj.objects.length; i++) {
             myChart.data.datasets[0].data[i] =obj.objects[i].Age;
             myChart.data.labels[i] =obj.objects[i].Name;
            
            }
            
                myChart.update();
           
            });

        });

</script>
</html>

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