[FR] Arrow annotations

[stevengj]

It would be nice to support adding arrow annotations to plots, similar to pyplot.arrow (from #245).

[BeastyBlacksmith]

I am not quite sure, what that function exactly is doing. Can you provide an example using PyPlot. First I thought this about marking points with arrows, but the example in the linked docs look like drawing an arrow with a label, which currently looks like this in Plots:

plot([(1,2), (2,3)], arrow=true, annotation=(1.45, 2.5, "label", 35.), legend=false)

[stevengj]

It just draws an arrow at an arbitrary position in the plot. Here's an example with PyPlot:

[BeastyBlacksmith]

I'd say we already have that... the above would read as

using Plots
plot(0:4, sqrt.(0:4), color = :red, legend = false)
plot!([(1,1.5), (2,0.5)], arrow = arrow(:closed, 0.1), color = :blue)

Though backend support for this varies and I think we should add a version of arrow that works with keywords.

[sarkarghya]

@BeastyBlacksmith Mind if I work on this issue?

[BeastyBlacksmith]

No, Not at all :)

[BoundaryValueProblems]

It would be really great if the plotlyjs backend also supports these arrow constructions. Currently, the arrow attribute is not supported in the plotlyjs somehow.