dash_simple_example_pandas_datareader.py

import dash
from dash.dependencies import Input, Output
import dash_core_components as dcc
import dash_html_components as html

from pandas_datareader import data as web
from datetime import datetime as dt

app = dash.Dash('Hello World')

app.layout = html.Div([
    dcc.Dropdown(
        id='my-dropdown',
        options=[
            {'label': 'Coke', 'value': 'COKE'},
            {'label': 'Tesla', 'value': 'TSLA'},
            {'label': 'Apple', 'value': 'AAPL'}
        ],
        value='COKE'
    ),
    dcc.Graph(id='my-graph')
], style={'width': '500'})

@app.callback(Output('my-graph', 'figure'), [Input('my-dropdown', 'value')])
def update_graph(selected_dropdown_value):
    df = web.DataReader(
        selected_dropdown_value,
        'google',
        dt(2017, 1, 1),
        dt.now()
    )
    return {
        'data': [{
            'x': df.index,
            'y': df.Close
        }],
        'layout': {'margin': {'l': 40, 'r': 0, 't': 20, 'b': 30}}
    }

app.css.append_css({'external_url': 'https://codepen.io/chriddyp/pen/bWLwgP.css'})

if __name__ == '__main__':
    app.run_server()

found that this example works only after following dependencies are installed:
pip install plotly==2.0.11 pip install dash==0.17.5 pip install dash_renderer pip install dash_html_components pip install pandas_datareader

For more about how this example works and how to install the necessary dependencies, please see the official dash user guide at https://dash.plot.ly. Thank you!

The user guide instructions for the installation at https://plot.ly/dash is very specific about which version of each library to install. Do you know if we could just install those libraries without specifying the version?

@PierreBourgault You could install without version numbers - it works for the current setup . But may fail in the future.

Am I the only that gets an error like this when running the example? The error seems to be from fetching the data to plot.
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xf8 in position 359: invalid start byte`

It looks like Google problem, try yaho. Work fine for me
df = web.DataReader(
selected_dropdown_value,
'yahoo',
dt(2017, 1, 1),
dt.now()
)

how to run a dash application can anybody tell me coz i am getting an error while running the code on jupyter i.e. system exit and also tell me from where i can access the app

Not 'google' nor 'yahoo' is currently working, please provide some valid source

you can use quandl instead , ex below 👍

import dash
from dash.dependencies import Input, Output
import dash_core_components as dcc
import dash_html_components as html

from pandas_datareader import data as web
from datetime import datetime as dt
import quandl

app = dash.Dash('Hello World')

app.layout = html.Div([
dcc.Dropdown(
id='my-dropdown',
options=[
{'label': 'Poxel', 'value': 'EURONEXT/POXEL'},
{'label': 'Orange', 'value': 'EURONEXT/ORA'},
{'label': 'TechnipFMC', 'value': 'EURONEXT/FTI'}
],
value='Poxel'
),
dcc.Graph(id='my-graph')
], style={'width': '500'})

@app.callback(Output('my-graph', 'figure'), [Input('my-dropdown', 'value')])
def update_graph(selected_dropdown_value):
df = quandl.get(
selected_dropdown_value,
authtoken="your_access_token_after_registering_to_quandl"
)
return {
'data': [{
'x': df.index,
'y': df.Last
}],
'layout': {'margin': {'l': 40, 'r': 0, 't': 20, 'b': 30}}
}

app.css.append_css({'external_url': 'https://codepen.io/chriddyp/pen/bWLwgP.css'})

if name == 'main':
app.run_server()

It works

Installed all dependencies, but I get the following error from my jupyter lab.
Using pipenv with Google Cloud VM & Ubuntu 16.04
Thanks,

UnsupportedOperation Traceback (most recent call last)
in ()
37
38 if name == 'main':
---> 39 app.run_server()

~/.local/share/virtualenvs/simulation-RVBo82bs/lib/python3.6/site-packages/dash/dash.py in run_server(self, port, debug, **flask_run_options)
566 debug=False,
567 **flask_run_options):
--> 568 self.server.run(port=port, debug=debug, **flask_run_options)

~/.local/share/virtualenvs/simulation-RVBo82bs/lib/python3.6/site-packages/flask/app.py in run(self, host, port, debug, load_dotenv, **options)
936 options.setdefault('threaded', True)
937
--> 938 cli.show_server_banner(self.env, self.debug, self.name, False)
939
940 from werkzeug.serving import run_simple

~/.local/share/virtualenvs/simulation-RVBo82bs/lib/python3.6/site-packages/flask/cli.py in show_server_banner(env, debug, app_import_path, eager_loading)
627 message += ' (lazy loading)'
628
--> 629 click.echo(message)
630
631 click.echo(' * Environment: {0}'.format(env))

~/.local/share/virtualenvs/simulation-RVBo82bs/lib/python3.6/site-packages/click/utils.py in echo(message, file, nl, err, color)
257
258 if message:
--> 259 file.write(message)
260 file.flush()
261
UnsupportedOperation: not writable

So where does one start feeling the need for the paid product or get stumped without it?
what's missing in starting the server with code like this, v.s. the premium product? excluding security or enterprise integration features....

I'm running the above code using Spyder/Anaconda. When opening local host on port 8050, I only see a White window with "Loading..." on the top. Can anyone please help me?

datasource 'yahoo' works for me currently (Google does not)

I seem to be getting hung up at the decorator and the def update_graph. I get the * Running on http://127.0.0.1:8050/ (Press CTRL+C to quit) and then the program hangs.

Any ideas?

How about if i would like to use a dataset on that sample code?

How about if i would like to use a dataset on that sample code?

HELP PLEASE! I am a student and I trying to create a graph to show volunteer impacts. Nothing fancy. I tried the simple graph and that didn't work, now I have this one and its not working :(

ModuleNotFoundError Traceback (most recent call last)
in
4 import dash_html_components as html
5
----> 6 import pandas.io.data as web
7
8

ModuleNotFoundError: No module named 'pandas.io.data'

@aboucher410 please look at the basics of python before putting the hands on this code.
The error you see is because you do not have the library pandas installed.
Look up at how to use virtualenvironments and pip. From a Terminal you would need to type the following commands (assuming you are on linux, and you have admin permissions):

sudo apt-get update
sudo apt-get -y upgrade

# install pip
sudo apt-get install -y python3-pip

# install virtualenv
pip install virtualenv

# create a virtualenv called `py3` in the folder `~/virtualenvs`, where you will have a shiny new python interpreter with the require libraries
mkdir ~/virtualenvs
venv -p=python3 --always-copy ~/virtualenvs/py3
source ~/virtualenvs/bin/activate

# be sure you are inside your virtualenv
python
import os
os.__file__  # this would show you a path inside your virtualenv.
quit()

# (and also)
which pip  # this too should show you a path inside your virtualenv 

Now, save all the required libraries in a file called requirements.txt, in the same folder where you have the python module above, one library for each line. It would look like:

plotly==2.0.11
dash==0.17.5 
dash_renderer
dash_html_components
pandas
pandas_datareader

Continue from the terminal:

# install the library from the file
cd <insert the folder path where you have the code>
pip install -r requirements.txt

# run the code above (... inside the virtualenv you just created)
# (you may need to replace google with yahoo, see comments above).
python  dash_simple_example_pandas_datareader.py 

# Just to clean up after the work, deactivate your virtualenv
deactivate

# look that you are outside virtualenv
python
import os
os.__file__  # This has no path to virtualenv

There is a lot, and few details of why. Do not be discouraged if something does not work at the first attempt. Look up each problem you may encounter and try to solve it with google. In any case, please read the documentation about pip and virtualenv to get the basics, and in particular to grasp the reasons why we need them.
Hope it helps.