Enable the opportunity for a Legend for single data objects

[mosc9575]

At the moment hvplot doesn't offer the opportunity to add a legend if the data only has one entry.

The example below uses pandas, but I think this is also true for xarray and maybe others.

If I plot a line plot for a DataFrame with only on column, the y label is set by the name of the column. I can overwrite the default y label, but I can't force a legend, even in the docs it says legend is true by default.

import pandas as pd
import hvplot.pandas

df=pd.DataFrame({'a':[1,2,3], 'b':[3,2,1]})
df[['a']].hvplot(ylabel='€', legend='bottom') + df.hvplot(ylabel='€', legend='bottom')

I think it makes sense that a legend is deactivated for single column date by default, but it would be create, I a get the change to add one.

software details

Python version        :  3.12.4 (tags/v3.12.4:8e8a4ba, Jun  6 2024, 19:30:16) [MSC v.1940 64 bit (AMD64)]
IPython version       :  8.25.0
Tornado version       :  6.4.1
Bokeh version         :  3.4.3
BokehJS static path   :  C:\Users\mosc\Envs\fbpinn\Lib\site-packages\bokeh\server\static
node.js version       :  (not installed)
npm version           :  (not installed)
jupyter_bokeh version :  4.0.5
Operating system      :  Windows-10-10.0.19045-SP0
hvplot version        :  0.10.0

[hoxbro]

This needs to be done in HoloViews: holoviz/holoviews#4196