python – Imshow Plotly colour toggling using legend

To create an interactive plot in Python using Plotly with a color toggling feature using a legend, you can use the plotly.graph_objects module along with some callbacks from the dash library. Here’s a simple example:

import dash
from dash import dcc, html
from dash.dependencies import Input, Output
import plotly.express as px
import pandas as pd

# Sample data
df = pd.DataFrame({
    'x': [1, 2, 3, 4, 5],
    'y1': [10, 6, 11, 8, 9],
    'y2': [8, 5, 7, 10, 6],
    'y3': [5, 4, 3, 2, 7]
})

# Create a Dash web application
app = dash.Dash(__name__)

# Layout of the app
app.layout = html.Div([
    dcc.Graph(id='scatter-plot'),
    html.Label('Toggle Series:'),
    dcc.Checklist(
        id='toggle-series',
        options=[
            {'label': 'y1', 'value': 'y1'},
            {'label': 'y2', 'value': 'y2'},
            {'label': 'y3', 'value': 'y3'}
        ],
        value=['y1', 'y2', 'y3']
    )
])

# Callback to update the plot based on toggled series
@app.callback(
    Output('scatter-plot', 'figure'),
    [Input('toggle-series', 'value')]
)
def update_plot(selected_series):
    # Filter the dataframe based on selected series
    filtered_df = df[['x'] + selected_series]

    # Create scatter plot using Plotly Express
    fig = px.scatter(filtered_df, x='x', y=selected_series, title='Scatter Plot')

    # Update legend
    fig.update_traces(showlegend=True, legendgroup='group')

    return fig

# Run the app
if __name__ == '__main__':
    app.run_server(debug=True)

This example uses the dash library to create a simple web application with a scatter plot. The dcc.Checklist component is used for selecting the series to display, and the callback function (update_plot) updates the scatter plot based on the selected series. The legend is updated accordingly to display only the selected series. The legendgroup attribute ensures that the legends are grouped together.