Smarter defaults for layout.hovermode

[joshua-gould]

Please see http://codepen.io/anon/pen/akKOvE for an example.

[etpinard]

Confirmed. Thanks.

[etpinard]

Looking at this issue again, I'm thinking this is the desired behavior under layout.hovermode: 'x' which is the default in your case because not all traces are horizontal (see logic here).

Setting layout.hovermode to either 'y' or 'closest' gives the desired behavior.

[alexcjohnson]

setting layout.hovermode to 'y' in this case mucks up hover for the rug trace, so that's not a good option. But I think what this points to is that "compare" mode is only a good default hover mode in certain (albeit very common) cases - where there are multiple traces of the same type with monotonic data mostly in common for the "compare" axis. What we should really do is default to 'closest' if any of those conditions is not met. That would help in even relatively simple cases like one or more scatter traces with nonmonotonic points (and perhaps we could even figure out if it's y that's monotonic instead of x and switch to hovermode: 'y'). Renaming this issue accordingly.

[etpinard]

Adding this to the v2 milestone