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Plotly: is there a way to save the data of a clicked point in a list?

I have a 2D plotly graph with a hover feature. When you hover over each point, the label (e.g. 'image 2, cluster 1') associated with that point appears. I'd like for label to be appended onto an existing list if I were to click on the point (rather than just hover over it). The reason why is that I'd later like to use the data of this point to perform another task. Is there an example online that demonstrates how to do this-- have looked through the documentation but haven't found something for this yet. Thanks!

The hoverData that is available to you by default, with some sample data, is this:
{
"points": [
{
"curveNumber": 1,
"pointNumber": 7,
"pointIndex": 7,
"x": 1987,
"y": 74.32,
"bbox": {
"x0": 420.25,
"x1": 426.25,
"y0": 256,
"y1": 262
}
}
]
}
I'm not quite sure what you mean by 'label', so I can only assume that it would be the name of a trace or something similar, like in this example from the Plotly docs:
But as you can see, that's not readily available in the hoverData dict. This means that you'll have to use this information to reference your figure structure as well, so that you end up with something like this:
[['New Zealand', 2002, 79.11]]
And that's not a problem as long as you're willing to use Plotly Dash. I've made a complete setup for you that should meet your requirements. In the app in the image below you'll find a figure along with two output fields for strings. The first field shows the info from that last point you've clicked in the figure. On every click, a new element is added to a list named store. The last fields shows the complete information from the same click.
The answer to your question is, yes, there is a way to save the data of a clicked point in a list. And one way to do so is through the following callback that uses clickdata to reference your figure object, store those references in a list, and append new elements every time you click a new element.
App
Complete code:
import json
from textwrap import dedent as d
import pandas as pd
import plotly.graph_objects as go
import numpy as np
import dash
from dash import dcc
import dash_html_components as html
import plotly.express as px
from dash.dependencies import Input, Output
from jupyter_dash import JupyterDash
import warnings
warnings.simplefilter(action='ignore', category=FutureWarning)
# app info
app = JupyterDash(__name__)
styles = {
'pre': {
'border': 'thin lightgrey solid',
'overflowX': 'scroll'
}
}
# data
df = px.data.gapminder().query("continent=='Oceania'")
# plotly figure
fig = px.line(df, x="year", y="lifeExp", color="country", title="No label selected")
fig.update_traces(mode="markers+lines")
app.layout = html.Div([
dcc.Graph(
id='figure1',
figure=fig,
),
html.Div(className
='row', children=[
html.Div([
dcc.Markdown(d("""Hoverdata using figure references""")),
html.Pre(id='hoverdata2', style=styles['pre']),
], className='three columns'),
html.Div([
dcc.Markdown(d("""
Full hoverdata
""")),
html.Pre(id='hoverdata1', style=styles['pre']),
], className='three columns')
]),
])
# container for clicked points in callbacks
store = []
#app.callback(
Output('figure1', 'figure'),
Output('hoverdata1', 'children'),
Output('hoverdata2', 'children'),
[Input('figure1', 'clickData')])
def display_hover_data(hoverData):
if hoverData is not None:
traceref = hoverData['points'][0]['curveNumber']
pointref = hoverData['points'][0]['pointNumber']
store.append([fig.data[traceref]['name'],
fig.data[traceref]['x'][pointref],
fig.data[traceref]['y'][pointref]])
fig.update_layout(title = 'Last label was ' + fig.data[traceref]['name'])
return fig, json.dumps(hoverData, indent=2), str(store)
else:
return fig, 'None selected', 'None selected'
app.run_server(mode='external', port = 7077, dev_tools_ui=True,
dev_tools_hot_reload =True, threaded=True)

You need to use callbacks to perform this type of action (register on_click()). Have defined clicked as a list of clicked points. Demonstrated how this can be achieved with ipwidgets or dash
ipwidgets
import numpy as np
import plotly.express as px
import plotly.graph_objects as go
import ipywidgets as widgets
from pathlib import Path
import json
x = np.random.uniform(-10, 10, size=50)
y = np.sin(x)
clicked = []
# construct figure that has holders for points, interpolated line and final lines
fig = go.FigureWidget(
[
go.Scatter(x=x, y=y, mode="markers", name="base_points"),
]
)
fig.update_layout(template="simple_white")
out = widgets.Output(layout={"border": "1px solid black"})
out.append_stdout("Output appended with append_stdout\n")
# create our callback function
#out.capture()
def base_click(trace, points, selector):
global clicked
clicked.append(points.__dict__)
fig.data[0].on_click(base_click)
widgets.HBox([fig, out])
dash
from jupyter_dash import JupyterDash
import dash
from dash.dependencies import Input, Output, State
import numpy as np
import json
clicked = []
# Build App
app = JupyterDash(__name__)
app.layout = dash.html.Div(
[
dash.dcc.Graph(
id="fig",
figure=go.Figure(go.Scatter(x=x, y=y, mode="markers", name="base_points")),
),
dash.html.Div(id="debug"),
]
)
#app.callback(
Output("debug", "children"),
Input("fig", "clickData"),
)
def point_clicked(clickData):
global clicked
clicked.append(clickData)
return json.dumps(clickData)
# Run app and display result inline in the notebook
app.run_server(mode="inline")

dash drawing different graph when clicking on different button

I want to draw graph A when clicking on button A and graph B when clicking on button B, if either graphs is drawn and I click on either button I want the page to be updated with the new graph, I'm using dash and plotly, here the pseudo code
#app.callback([Output("graph-content", "children")],[Input("KPI_gauge","n_clicks")])
def kpi_gauge(v):
if v == None:
raise PreventUpdate
fig1 = KPIGauge(88.7,102)
return [dcc.Graph(figure=fig1)]
#app.callback([Output("graph-content", "children")],[Input("comparaison_graph","n_clicks")]
def comparaison_graph(v):
if v == None:
raise PreventUpdate
fig = ComparaisonGraph()
return [dcc.Graph(figure=fig)]
but I get this error dash duplicate callback output, how to resolve this error?

https://dash.plotly.com/callback-gotchas A component/property pair can only be the Output of one callback. Your code broke this rule, graph-content was the output of two callbacks
this code demonstrates a way to output plotly figure on first click and update data in graph on subsequent clicks
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output, State
from dash.exceptions import PreventUpdate
import dash
from jupyter_dash import JupyterDash
import random
import plotly.graph_objects as go
import plotly.express as px
import pandas as pd
import numpy as np
# Build App
app = JupyterDash(__name__)
app.layout = html.Div(
[
html.Button("KPI", id="KPI_gauge", n_clicks=0),
html.Button("Graph", id="comparaison_graph", n_clicks=0),
html.Div(id="graph-content"),
]
)
#app.callback(
Output("graph-content", "children"),
Input("KPI_gauge", "n_clicks"),
Input("comparaison_graph", "n_clicks"),
State("graph-content", "children"),
)
def update_graph(kpi_but, graph_but, content):
if not kpi_but and not graph_but:
raise PreventUpdate
ctx = dash.callback_context
button = ctx.triggered[0]["prop_id"].split(".")[0]
fig_id = f"{button}_fig"
if button=="KPI_gauge":
if content and content["type"]=="Graph" and content["props"]["id"]==fig_id: # update
fig = content["props"]["figure"]
fig["data"][0]["value"] = random.randint(0,400)
else: # create
fig = go.Figure(go.Indicator(mode="gauge+number",value=270,title={"text": "KPI"},))
elif button=="comparaison_graph":
if content and content["type"]=="Graph" and content["props"]["id"]==fig_id: # update
fig = content["props"]["figure"]
fig["data"][0]["y"] = np.sort(np.random.uniform(1,5,365*2))
else: # create
df = pd.DataFrame({"date":pd.date_range("1-aug-2019", periods=365*2), "value":np.linspace(1,5,365*2)})
fig = px.line(df, x="date", y="value")
else:
raise PreventUpdate
return dcc.Graph(id=fig_id, figure=fig)
app.run_server(mode="inline", port=8051)

Change the language in dash/plotly

I want to change the language of dash's core components and the toolbar in plots (to german). I thought that defining external_scripts would be sufficient, but its still showing everything in english. Here is a minimal example of my code:
import dash
import dash_core_components as dcc
import dash_html_components as html
import plotly.express as px
from datetime import datetime as dt
external_scripts = ["https://cdn.plot.ly/plotly-locale-de-latest.js"]
app = dash.Dash(__name__, external_scripts=external_scripts)
data_canada = px.data.gapminder().query("country == 'Canada'")
fig = px.bar(data_canada, x='year', y='pop')
app.layout = html.Div(children=[
html.H1(children='Dashboard'),
dcc.DatePickerRange(
id="date_range_picker",
min_date_allowed=dt(2018,1,1),
max_date_allowed=dt(2020,12,31),
display_format="MMM, YYYY"
),
dcc.Graph(
id='example-graph',
figure=fig
)
])
if __name__ == '__main__':
app.run_server(debug=True)
What else do I have to do to change the language?

You must add:
config_plots = dict(locale='de')
to:
dcc.Graph(
id='example-graph',
figure=fig,
config=config_plots
)

Null is not an object (evaluating ‘n.layout’) in Dash Plotly

I am developing dashboard using Dash Plotly and I am getting an error when I click tabs.
The error says null is not an object (evaluating ‘n.layout’)
(This error originated from the built-in JavaScript code that runs Dash apps. Click to see the full stack trace or open your browser’s console.)"
Can any one help me to solve this problem?
My code is found below.
import dash
import dash_core_components as dcc
import dash_html_components as html
import dash_daq as daq
from dash.dependencies import Input, Output
import plotly.graph_objs as go
import pandas as pd
import numpy as np
from copy import copy
import dash_table
import json
import base64
import plotly.express as px
#Data
errors = pd.read_csv(r’/Users/kapital/Documents/ABCD/PM/errors.csv’)
external_stylesheets = [‘https://codepen.io/chriddyp/pen/bWLwgP.css’]
app = dash.Dash(name, external_stylesheets=external_stylesheets)
first_graph = dcc.Graph(id=‘graph1’,style={‘borderBottom’: ‘thin lightgrey solid’,‘padding’: ‘10px 5px’})
#, animate = True
content_tab_1 = html.Div(children = [
html.Div(first_graph, style = {‘vertical-align’:‘center’, ‘horizontal-align’:‘center’})
],
style={‘width’: ‘87%’})
app.layout = html.Div([
dcc.Tabs(id='tabs-example', value='tab-1', children=[
dcc.Tab(label='Tab one', value='tab-1',
children =[content_tab_1]),
dcc.Tab(label='Tab two', value='tab-2'),
]),
html.Div(id='tabs-example-content')
])
#app.callback(Output(‘graph1’, ‘figure’),
Input(‘tabs-example’, ‘value’))
def render_content(tab):
if tab == ‘tab-1’:
err_count = pd.DataFrame(errors['errorID'].value_counts().reset_index().values, columns=["Error", "Count"])
err_count = err_count.sort_index(axis = 0, ascending=True)
fig = px.bar(err_count, x = 'Error', y = 'Count')
return fig
# return html.Div([
# html.H3('Tab content 1')
# ])
if name == ‘main’:
app.run_server(debug=True)

The problem is that your callback function does not have an else to its conditional statement. When the user selects the second tab, that callback has no alternate path, and returns None, which gives you the error you see. I did this to fix it, but you'll probably want something more:
#app.callback(Output('graph1', 'figure'),
Input('tabs-example', 'value'))
def render_content(tab):
if tab == 'tab-1':
err_count = pd.DataFrame.from_dict(dict(
Error=[1, 2, 3, ],
Count=[5, 6, 7])
)
err_count = err_count.sort_index(axis=0, ascending=True)
fig = px.bar(err_count, x='Error', y='Count')
return fig
else:
return {}

Error while running Dash app locally, "This site can’t be reached"

I'm trying to run (locally) a sample dash app code but I'm always getting a mistake while opening the window.
I'm using Jupyter Notebook and sometimes PyCharm for testing. The code I'm running is this:
import dash
import dash_core_components as dcc
import dash_html_components as html
import dash_bootstrap_components as dbc
import plotly
import plotly.graph_objs as go # for making plot.ly graph objects
from dash.dependencies import Input, Output
from collections import deque
import random
X = deque(maxlen = 20)
X.append(1)
Y = deque(maxlen = 20)
Y.append(1)
app = dash.Dash(__name__)
# Layout
app.layout = html.Div([
dcc.Graph(id = 'live-graph', animate = True),
dcc.Interval(id = 'graph-update', interval = 1000)
])
# Callbacks
#app.callback(Output('live-graph', 'figure'),
[Input('graph-update', 'n_intervals')])
def update_graph(input_data):
X.append(X[X[-1] + 1])
Y.append(Y[Y[-1] + (Y[-1]*random.uniform[-0.1, 0.1])])
data = gp.Scatter(
x = list(X),
y = list(Y),
name = 'Temperature',
mode = 'lines + markers'
)
return {'data':[data], 'layout':go.Layout(xaxis = dict(range = [min(X), max(X)]),
yaxis = dict(range = [min(Y), max(Y)])
)}
if __name__ == "__main__":
app.run_server(host = '0.0.0.0', port = 8050, debug = True)
I already tried changing the port to 8050 and debug = False.
Image Error

If you're using 0.0.0.0:8050 you should be accessing your site at localhost:8050.