Issue
I am currently trying to successfully plot a bar chart when the results from the dataframe is updated or when there is any change in the data.
Setup:
- Flask-SocketIO==4.3.1
- python-engineio==3.13.2
- python-socketio==4.6.0
Make sure you restart your machine to not encounter errors.
Python Code -saved in D:\Projects\test_backgroundtask:
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 Code (saved in D:\Projects\test_backgroundtask\template\views):
<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>
Output:
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 -
First output even though dataframe is updated.
After reloading the page, the page is blank and then displays correct chart.
What I would like to achieve:
- Automatically display the bar chart when dataframe is updated without reloading page.
Solution
In function(receiving_data) found in the html page , variable plot is used instead of receiving_data. Variable plot is initialized when render_template is evoked. When data is being emitted via sockets, you do not need to pass variable plot when return render_template('views/index_img_soc.html', plot=bar) is called.
See example script below on how to emit data using sockets to the html script.
The script below will automatically update a bar chart without reloading the page.
The code using chart.js instead of plotly. There are much more examples plotting chart.js in javascript as opposed to plotly.
Updated Python script:
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)
Updated html script:
<!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>
Answered By - Sade
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