I need to plot data with continuous error bands. I would like to use Plotly Express in the same way as plotly.express.scatter, but instead of error bars to get continuous error bands. With "continuous error bands" I am talking about this:

I wrote the following function to extend plotly.express.line with the same high level interface of Plotly Express. In case it is useful to other people, this is the function:

import plotly.express as px
import plotly.graph_objs as godef line(error_y_mode=None, **kwargs):"""Extension of `plotly.express.line` to use error bands."""ERROR_MODES = {'bar','band','bars','bands',None}if error_y_mode not in ERROR_MODES:raise ValueError(f"'error_y_mode' must be one of {ERROR_MODES}, received {repr(error_y_mode)}.")if error_y_mode in {'bar','bars',None}:fig = px.line(**kwargs)elif error_y_mode in {'band','bands'}:if 'error_y' not in kwargs:raise ValueError(f"If you provide argument 'error_y_mode' you must also provide 'error_y'.")figure_with_error_bars = px.line(**kwargs)fig = px.line(**{arg: val for arg,val in kwargs.items() if arg != 'error_y'})for data in figure_with_error_bars.data:x = list(data['x'])y_upper = list(data['y'] + data['error_y']['array'])y_lower = list(data['y'] - data['error_y']['array'] if data['error_y']['arrayminus'] is None else data['y'] - data['error_y']['arrayminus'])color = f"rgba({tuple(int(data['line']['color'].lstrip('#')[i:i+2], 16) for i in (0, 2, 4))},.3)".replace('((','(').replace('),',',').replace(' ','')fig.add_trace(go.Scatter(x = x+x[::-1],y = y_upper+y_lower[::-1],fill = 'toself',fillcolor = color,line = dict(color = 'rgba(255,255,255,0)'),hoverinfo = "skip",showlegend = False,legendgroup = data['legendgroup'],xaxis = data['xaxis'],yaxis = data['yaxis'],))# Reorder data as said here: https://stackoverflow.com/a/66854398/8849755reordered_data = []for i in range(int(len(fig.data)/2)):reordered_data.append(fig.data[i+int(len(fig.data)/2)])reordered_data.append(fig.data[i])fig.data = tuple(reordered_data)return fig

and this is an usage example:

import plotly.express as px
import pandasdf = px.data.gapminder().query('continent=="Americas"')
df = df[df['country'].isin({'Argentina','Brazil','Colombia'})]
df['lifeExp std'] = df['lifeExp']*.1 # Invent some error data...for error_y_mode in {'band', 'bar'}:fig = line(data_frame = df,x = 'year',y = 'lifeExp',error_y = 'lifeExp std',error_y_mode = error_y_mode,color = 'country',title = f'Using error {error_y_mode}',markers = '.',)fig.show()

which should produce the following two plots: