Passing go.fig to a function that add traces and return fig

[jharm]

Hi I am inititialising my figure and then want to add traces.

But when create a function to do it it does not work. Is this a python thing when passing an object and return the same object?

def update_fig_transient(fig1, fig2, fig3, df, dp):
    fig1.add_trace(go.Scatter(x=df['time [s]'], 
                            y=df['OUT'], 
                            mode='lines', 
                            name='Voltage',
                            legendgroup='Design point {}'.format(dp), 
                            legendgrouptitle_text='Design point {}'.format(dp),
                            line=dict(color=colors[dp-1])
                            ))
        
    fig2.add_trace(go.Scatter(x=df['time [s]'], 
                            y=df['Load current'], 
                            mode='lines', 
                            name='Current',
                            legendgroup='Design point {}'.format(dp), 
                            legendgrouptitle_text='Design point {}'.format(dp),
                            line=dict(color=colors[dp-1])
                            ))

    fig3.add_trace(go.Scatter(x=df['time [s]'], 
                            y=df['Inductor current'], 
                            mode='lines', 
                            name='Current',
                            legendgroup='Design point {}'.format(dp),  
                            legendgrouptitle_text='Design point {}'.format(dp),
                            line=dict(color=colors[dp-1])
                            ))
    return fig1, fig2, fig3

fig1 = go.Figure()
fig2 = go.Figure()
fig3 = go.Figure()

fig1, fig2, fig3 = update_fig_transient(fig1, fig2, fig3, df, dp)

[Skiks]

Hi @jharm,

I made a quick test, it seems to work:

Code

import numpy as np
from dash import Dash, dcc
import plotly.graph_objects as go

app = Dash(__name__)

x = np.arange(-10, 10)


def update_figs(fig1, fig2, fig3):
    fig1.add_scatter(x=x, y=x)
    fig2.add_scatter(x=x, y=x ** 2)
    fig3.add_scatter(x=x, y=x ** 3)
    return fig1, fig2, fig3


fig1 = go.Figure()
fig2 = go.Figure()
fig3 = go.Figure()

fig1, fig2, fig3 = update_figs(fig1, fig2, fig3)

fig1.update_layout(margin={'l': 0, 'r': 0, 't': 0, 'b': 0})
fig2.update_layout(margin={'l': 0, 'r': 0, 't': 0, 'b': 0})
fig3.update_layout(margin={'l': 0, 'r': 0, 't': 0, 'b': 0})

app.layout = [
    dcc.Graph(figure=fig1, style={'height': 200}),
    dcc.Graph(figure=fig2, style={'height': 200}),
    dcc.Graph(figure=fig3, style={'height': 200})
]

if __name__ == "__main__":
    app.run(debug=True)

But I think, you don’t need to reassign fig1, fig2, fig3 with the outputs of the function.
That should also work:

Code

import numpy as np
from dash import Dash, dcc
import plotly.graph_objects as go

app = Dash(__name__)

x = np.arange(-10, 10)


def update_figs(fig1, fig2, fig3):
    fig1.add_scatter(x=x, y=x)
    fig2.add_scatter(x=x, y=x ** 2)
    fig3.add_scatter(x=x, y=x ** 3)


fig1 = go.Figure()
fig2 = go.Figure()
fig3 = go.Figure()

update_figs(fig1, fig2, fig3)

fig1.update_layout(margin={'l': 0, 'r': 0, 't': 0, 'b': 0})
fig2.update_layout(margin={'l': 0, 'r': 0, 't': 0, 'b': 0})
fig3.update_layout(margin={'l': 0, 'r': 0, 't': 0, 'b': 0})

app.layout = [
    dcc.Graph(figure=fig1, style={'height': 200}),
    dcc.Graph(figure=fig2, style={'height': 200}),
    dcc.Graph(figure=fig3, style={'height': 200})
]

if __name__ == "__main__":
    app.run(debug=True)

Did you try to plot your figures without a function to see if the parameters are fine?

[jharm]

That’s strange. The way I do it. Then I first initialize the figure. And then dependent on input there are 1 or more traces to be added. When I do this using a function it did not work. But if I use a for loop then it worked. Each traces will then be called design point 1 design point 2 etc.

[jharm]

by the way, now when thinking about it. Then I should probably create the complete data frame first in long format and then create the figure in the end.