Draw vertical or horizontal lines on plots

[acarl005]

Drawing arbitrary vertical or horizontal lines on plot (scatter plots or histograms) is generally very useful, something analogous to this in matplotlib.

[tammoippen]

Hello @acarl005, thanks for the suggestion. I think they can easily be implemented in Figure by adding a methods, that use the plot function with two coordinates in X and Y, respectively. Are you interested in providing a PR? Otherwise I will look into this, but it might take some weeks for me to find the time.

[acarl005]

For the API, what did you have in mind? If I wanted to create a vertical line at x = 5, maybe something like fig.plot(X=5) where Y argument is omitted?

[tammoippen]

I think, i would prefer a new function for each, vlines(x) and hlines(y), as close as possible to https://matplotlib.org/3.1.0/api/_as_gen/matplotlib.axes.Axes.vlines.html#matplotlib.axes.Axes.vlines

[tammoippen]

Implemented in #38. Closing