Waterfall charts

[b4D8]

Hi! Thanks for this very clean and useful library.

Quick thoughts. I think it would be great if we could support waterfall charts like:

from MS Office

This can probably be realized by enhancing the bar chart with each bar starting point being set relatively to its predecessor, rather than at 0.

An optional complementary feature would be special bars for intermediate sums.

If you think its relevant, I can take a stab at it.

As i'm new to this library, I would appreciate if you could put me on the right track.

[ramiy]

I already started working on this feature:

• acb290e
• 8c22478

Not sure when it will be ready but the basic idea is to use --start & --end variables instead of --size variable. This way you can control the starting and the ending point.