Change linewidth in python plotly px figure

Question

I'm unclear how to style a line in a plotly express figure, altering color and width. The plotly documentation offers suggestions to style lines using go, but I do not see information for px.

Example

import plotly.express as px

df = px.data.gapminder().query("continent=='Oceania'")
fig = px.line(df, x="year", y="lifeExp", color='country')
fig.show()

I tried putting line=dict(color='firebrick', width=4) as an argument of px.line but that throws the error line() got an unexpected keyword argument 'line' as it is code for go rather than px.

Answer 1

Plotly px line styles can be updated with update_traces function see documentation for further information. The following example modifies the prior figure making all of the lines black and thin.

import plotly.express as px

df = px.data.gapminder().query("continent=='Oceania'")
fig = px.line(df, x="year", y="lifeExp", color='country')

# This styles the line
fig.update_traces(line=dict(color="Black", width=0.5))

fig.show()