Hi @nymosis,
You won’t be able to change the dash style within a single trace, but you should be able to do this with two separate traces.
Here’s a starting point for you
import pandas as pd
gdp = pd.DataFrame({'Year': [1990, 1991, 1992, 1993, 1994], 'Ukraine': [5, 4, 7, 4, 6]})
gdp1 = gdp.loc[gdp.Year <= 1992]
gdp2 = gdp.loc[gdp.Year >= 1992]
fig = go.FigureWidget(data=[
go.Scatter(x=gdp1.Year, y=gdp1.Ukraine, mode='lines', line={'dash': 'solid', 'color': 'green'}),
go.Scatter(x=gdp2.Year, y=gdp2.Ukraine, mode='lines', line={'dash': 'dash', 'color': 'green'}),
])
fig
Hope that helps!
-Jon