Format `hover_data`. Is this possible?

[indiana-nikel]

Hello,

I couldn't seem to find this in the docs. Is it possible to format hover_data as a string for display purposes only? My use case comes from displaying dollar amounts, but the original data is float.64 so hovering over a data point does not look appealing.

My current fix requires an extra column to be added to a data frame, then that column is passed to the hover_data argument:

df['hover_text'] = df['revenue'].apply(lambda x :'${0:,.0f}'.format(x))

However, this is not a great solution. My knowledge is pretty limited with plotly so there may be better solutions I haven't been able to find currently. Perhaps with hovertemplate?

Best,
Indiana

[nicolaskruchten]

Your solution is probably what I would go with, to be honest. The way hover_data is injected into the figure is via hovertemplate, and you can override hovertemplate with .update_trace(hovertemplate="whatever") if you like, but it's likely to be a bit finicky.

[indiana-nikel]

Okay thank you for your quick response! Are there plans to expose this when creating a plot?

Eg.

px.bar(
   df, 
   x="Revenue", 
   y="Year",
   hover_data={
      "Revenue": "${0:,.0f}", 
      ...
   })

Sidenote: Since discovering this plotting library, it's hard to go back to anything else!

[nicolaskruchten]

I'm glad you like it! The API you suggest above is pretty interesting, I'll think about it. The formatting strings would have to be D3.js-compatible rather than Python-compatible as the formatting happens in Javascript but other than that this seems like a nice extension.

[nicolaskruchten]

Will be completed in plotly/plotly.py#1774