Question

首先感谢Dash帮助我摆脱了网页应用中的互动式绘图。

最近我正在创建一个需要经常更新数据的应用程序。

该应用程序现在可以从mysql获取数据并更新数据和数据。问题是我将间隔设置为10秒，而每10秒我也可以看到数据是在服务器中实现和计算的，但是这个数字只能在大约每1分钟到50秒后随机更新。

我每隔10秒就可以看到网站点击的更新，但是直到50秒或1分钟更新才会发生任何事情。

此外， mysql服务器是本地的，查询时间快了大约2,3ms。计算时间约为100毫秒。

以下是我的应用的最多代码。

""" app plotly dash"""
import dash
from dash.dependencies import Input, Output, State, Event
import dash_core_components as dcc
import dash_html_components as html
import plotly.graph_objs as go
import numpy as np
import time
import sys
import datetime as dt
import matplotlib
matplotlib.use(“Agg”)
import matplotlib.pylab as plt
import base64
from login import server as server
import json

def global_store(data, strings):
    global_data = [v for i,v in enumerate(data)]
    print(‘Computing value…’)
    return [global_data, strings]

app = dash.Dash(name=‘app’, server=server, csrf_protect=False, 
    url_base_pathname=’/app’)

app.layout = html.Div([
html.Div([

    dcc.Interval(
        id='interval-component',
        interval=5*60*60*1000, # in milliseconds
        n_intervals=0
    ),

  html.Button(id='run', n_clicks=0, children='Run'),

  html.Div(id='signal', style={'display': 'none'}),
  html.Div(id='div-error'),
  ], style={'display': 'inline-block', 'textAlign': 'center', 
'marginLeft':'27%', 'marginTop':0}),

html.Div([
dcc.Slider(id='index-slider3', min=0, max=loops, value=0, step=1,),
], style={'width': '35%'}),

# Graphs

html.Div([
    html.H5("Waveform 1", style={'display': 'inline-block', 'marginLeft': 300}),
    dcc.Graph(id='fig1', style={'width':850, 'height': 450, 'marginTop':0, 'marginBottom':0}),],
style={'width': '60%', 'display': 'inline-block','marginTop': 0}),

html.Div([
    html.H5("Waveform 2", style={'display': 'inline-block', 'marginLeft': 300}),
    dcc.Graph(id='fig2', style={'width':850, 'height': 450, 'marginTop':0, 'marginBottom':0})],
style={'width': '60%', 'display': 'inline-block','marginTop': 0}),

html.Div([
    html.H5("Waveform 3", style={'display': 'inline-block', 'marginLeft': 300}),
    dcc.Graph(id='fig3', style={'width':850, 'height': 450, 'marginTop':0, 'marginBottom':0})],
style={'width': '60%', 'display': 'inline-block','marginTop': 0}),

html.Div([
    html.H5("Waveform 4", style={'display': 'inline-block', 'marginLeft': 300}),
    html.Img(id='fig4', style={'width':850, 'height': 450, 'marginTop':0, 'marginBottom':0})],
    style={'width': '60%', 'display': 'inline-block','marginTop': 0}),
])

@app.callback(Output(‘interval-component’, ‘interval’),
[Input(‘run’, ‘n_clicks’)])
def disable_interval(n_clicks):
    if n_clicks%2 == 0:
        return 106060*1000
    else:
        return 10 * 1000

@app.callback(Output(‘signal’, ‘children’),
[Input(‘interval-component’, ‘n_intervals’)],)
def compute_value(n_intervals):
    datas = np.random.randint(1000, size=5000)
    datass = np.random.randint(2, size=(5000,5000))
    plt.figure(figsize=(8, 6))
    plt.pcolormesh(datas [0:10], datass [10:100], datas [10:100,0:10])
    plt.colorbar()
    plt.title(‘Waveform at time: 
    {}.’.format(dt.datetime.now().strftime(’%c’)))
    plt.savefig(‘spectrum.png’)
    image_filename = ‘wave4.png’ # replace with your own image
    encoded_image = base64.b64encode(open(image_filename, ‘rb’).read())
    base64_string = encoded_image.decode(‘utf-8’)
    global_data = global_store(datas, base64_string)
    return json.dumps(global_data)

@app.callback(Output(‘div-error’, ‘children’), [Input(‘signal’, 
‘children’)], [], [Event(‘interval-component’, ‘interval’)])
def update_error(data):
      if ‘data’ in data:
           return data

@app.callback(Output(‘fig1’, ‘figure’), [Input(‘signal’, ‘children’)], [], 
[Event(‘interval-component’, ‘interval’)])
def update_figure1(data):
    data = json.loads(data)
    traces = []
    traces.append(go.Scatter(
    x=list(range(len(data[0]))),
    y=data[0],
    mode=‘lines’,#+markers’,
    opacity=0.7,
    ))
    return {
‘data’: traces,
‘layout’: go.Layout(
title=‘Waveform1’,
xaxis={‘title’: ‘Index’},
legend={‘x’: 0, ‘y’: 1},
hovermode=‘closest’
)
}

@app.callback(Output(‘fig2’, ‘figure’), [Input(‘signal’, ‘children’)], [], 
[Event(‘interval-component’, ‘interval’)])
def update_figure2(data):
    data = json.loads(data)
    traces = []
    traces.append(go.Scatter(
    x=list(range(len(data[0]))),
    y=data[0],
    mode=‘lines’,
    opacity=0.7,
    ))
    return {
    ‘data’: traces,
    ‘layout’: go.Layout(
    title=‘Waveform2’,
    legend={‘x’: 0, ‘y’: 1},
    hovermode=‘closest’
    )
    }

@app.callback(Output(‘fig3’, ‘figure’), [Input(‘signal’, ‘children’)], [], 
 [Event(‘interval-component’, ‘interval’)])
def update_figure5(data):
    data = json.loads(data)
    traces = []
    traces.append(go.Scatter(
    x=list(range(len(data[0]))),
    y= np.array(data[0]) * np.array(data[0]),
mode=‘line’,
name=“Power”,
))
return {
‘data’: traces,
‘layout’: go.Layout(
title=‘Waveform3’,
legend={‘x’: 0, ‘y’: 1},
hovermode=‘closest’
)
}

@app.callback(Output(‘fig4’, ‘src’), [Input(‘signal’, ‘children’)], [], [Event(‘interval-component’, ‘interval’)])
def update_figure6(data):
data = json.loads(data)
image = data[1]
return ‘data:image/png;base64,{}’.format(image.encode(‘utf-8’).decode())

if name == ‘main’:
app.run_server(host=‘0.0.0.0’, port=9000, debug=True)
# app.run_server()

” 这是服务器端的输出：

计算价值...... 127.0.0.1 - - [20 / Mar / 2018 16:50:08]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:08]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:08]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:08]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:08]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:08]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:08]“POST / app2_dash-update-component HTTP / 1.0”200 - Theta是：-0.30832596184310135 127.0.0.1 - - [20 / Mar / 2018 16:50:08]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:08]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:08]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:08]“POST / app2_dash-update-component HTTP / 1.0”200 - 4096.0计算价值...... 127.0.0.1 - - [20 / Mar / 2018 16:50:18]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:18]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:18]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:18]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:18]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:18]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:18]“POST / app2_dash-update-component HTTP / 1.0”200 - Theta is：-0.17874378214618614 127.0.0.1 - - [20 / Mar / 2018 16:50:18]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:18]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:18]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:18]“POST / app2_dash-update-component HTTP / 1.0”200 - 4096.0计算价值...... 127.0.0.1 - - [20 / Mar / 2018 16:50:28]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:28]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:28]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:28]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:28]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:28]“POST / app2_dash-update-component HTTP / 1.0”200 - Theta is：-0.17874378214618614 127.0.0.1 - - [20 / Mar / 2018 16:50:28]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:28]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:28]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:29]“POST / app2_dash-update-component HTTP / 1.0”200 - 127.0.0.1 - - [20 / Mar / 2018 16:50:29]“POST / app2_dash-update-component HTTP / 1.0”200 -

啊，这是控制台中的一个警告：

/home/mo/anaconda3/envs/tf35/lib/python3.5/site-packages/matplotlib/pyplot.py:537：   RuntimeWarning：

已经开设了20多个数字。通过数字创建的数字   pyplot接口（matplotlib.pyplot.figure）保留到   明确关闭，可能会消耗太多内存。（控制这一点   警告，请参阅rcParam figure.max_open_warning）。

我个人认为这意味着每10秒计算一次数据和图像，但数据仍然不会每10秒更新一次。

你能帮我解决这个问题吗？非常感谢。此外，我想将间隔设置为0.5秒，有没有更好的方法来进行频繁更新？

参考：https://community.plot.ly/t/help-interval-can-update-the-data-but-figure-not-updated-is-there-any-refresh-frequency-limit-in-dash/9089

Answer 1

最后我发现问题是由数据库延迟引起的。数据库每1分钟只更新一次数据。

Interval可以更新数据，但数字没有更新？短划线中是否有任何刷新频率限制？

1 个答案: