Support using DataFrame index for colors, labels, x, y, etc.

I often use the DataFrame index for something meaningful, such as a timestamp corresponding to when the data was taken, or a sequence number. In those cases, it’d be great to be able to use that in plotly express to determine the X value, data color, text label, etc.

Currently the workaround is to copy the index to a separate column, e.g.

# Contrived example, but this usually comes from some other system
df = pd.DataFrame({'y': [1,2,3]}, index=[4,5,6])
df['x'] = df.index

px.scatter(df, x=px.INDEX, y='y')

Instead of having to change the DataFrame, it would be nice if I could just go ahead and do something like

df = pd.DataFrame({'y': [1,2,3]}, index=[4,5,6])
px.scatter(df, x=px.INDEX, y='y')

or even, in the special case of using it as an X value, it could be the default:

px.scatter(df, y='y')

[nicolaskruchten]

This will be implemented as part of plotly/plotly.py#1767 … thanks for the input and patience 😃

[nicolaskruchten]

We’ve actually gone farther and implemented full wide-mode support: https://medium.com/plotly/beyond-tidy-plotly-express-now-accepts-wide-form-and-mixed-form-data-bdc3e054f891