pythonplotlypython-typingplotly-express

Type hint for output of plotly express?

If I have a function that returns a plotly express figure, what is the correct way of type hinting?

The figure is of type: <class 'plotly.graph_objs._figure.Figure'>.

Should I type hint by separately importing plotly, and writing: -> plotly.graph_objs._figure.Figure ?

import pandas as pd
import plotly.express as px
import plotly 
 
long_df = px.data.medals_long()

fig = px.bar(long_df, x="nation", y="count", color="medal", title="Long-Form Input")
print (type (fig))

def plot_bar (df: pd.DataFrame) -> plotly.graph_objs._figure.Figure :
  fig = px.bar(long_df, x="nation", y="count", color="medal", title="Long-Form Input")
  return fig

plot_bar(long_df)
Solution

  • It's a matter of convention, but usually when people work with plotly graph_objects, they have the following import:

    import plotly.graph_objects as go

    This means you can replace plotly.graph_objs._figure.Figure with go.Figure so your type hinting is a little easier to read:

    def plot_bar(df: pd.DataFrame) -> go.Figure():
  fig = px.bar(long_df, x="nation", y="count", color="medal", title="Long-Form Input")
  return fig