Plotly express should check if input data is tidy

Currently, it’s easy to run into internal errors like follows:

 --> 277  hover_lines = [k + "=" + v for k, v in mapping_labels.items()]
     278  result["hovertemplate"] = hover_header + "<br>".join(hover_lines)
     279  return result, fit_results

TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'

Whereas it would be good to check that the input dataframe is fine before charting, and issue a pinpointed error message rather than fail internally following the dirty python tradition.

[nicolaskruchten]

Fair enough.

In any case, we are working on more flexible input types, although the “tidy” philosophy will remain, i.e. you’ll still need to concatenate your vectors to do this sort of thing: https://stackoverflow.com/questions/57988604, you just won’t be required to stick them into a data frame first 😃

[matanster]

Thanks for your positive attitude! it seems that in defiance of python tradition, an input-safe library would be even more awesome than what plotly/express already is, especially given that charts need to be developed ad-hoc very typically, by people who don’t recall every caveat or limitation of the API at the moments when they come to create, iterate, and choose between visualizations.