simple app for clicking on data to label

dash.py

import dash
from dash import dcc
from dash import html
from dash.dependencies import Input, Output
import json

clicked = []
external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]

app = dash.Dash(external_stylesheets=external_stylesheets)
app.layout = html.Div(
    [
        dcc.Graph(figure=fig, id="graph"),
        html.Strong("Clicked Data"),
        html.Div(html.Pre([], id="click-data", style={"background-color": "#eeeeee"})),
    ]
)


def getdata(click_data):
    point = click_data["points"][0]
    data = dict(zip(point_customdata, point["customdata"]))
    return data


@app.callback(
    Output("click-data", "children"),
    Input("graph", "clickData"),
    prevent_initial_call=True,
)
def display_click_data(clickData):
    global clicked
    data = getdata(clickData)
    if data not in clicked:
        clicked.append(data)
    return json.dumps(clicked, indent=2)


app.run_server(
    debug=True, use_reloader=False, port=9877
)  # Turn off reloader if inside Jupyter