holoviews.Arrow support

[LecrisUT]

Is your feature request related to a problem? Please describe.

I was looking at adding some annotations to a plot, but I couldn't find the feature in the hvplot documentation about it either under arrow or annotation. I did find about holoviews.Arrow though. Using the "primitive" holoviews.Arrow is rather cumbersome though.

Describe the solution you'd like

Have additional wrappers like:

da.hvplot(kind="arrow", x="x", label="a")

The kind could be anything like arrow, annotation, etc. The behavior could be as follow:

• if label is provided, interpret the DataArray value as the equivalent y coordinate where to place the annotation
• if y is provided, get the y coordinate from that coordinate, and if label is also provided as a coordinate, select that, otherwise interpret the value of the DataArray as the label to plot

[ahuang11]

Would you be interested in helping contribute this feature? Happy to provide guidance if so!

By the way, currently, Holoviews Bokeh backend arrow is missing length so that needs help too!
holoviz/holoviews#3356

[LecrisUT]

Happy to take a crack at it, but will probably have to finish the current project that I am working at which spawns all of my issues and discussions, estimating 1-2 months before can have any free time.