Enable signal comparisons on time series plots

[ryantibs]

I'm using the dashboard frequently these days and I'm enjoying all the new fixes & simplifications. One thing that's missing for me is the ability to compare two signals at the same time, overlaid on a single time series plot. See the screenshot below as an example to build from:

I would like to have a toggle called "Compare Indicators". This could show up, say, on the right-hand side of the plot. If this were toggled on, then it would allow me to select from any of the indicators (that are available at the given location) to put on the same time series plot. The default selection would be nothing.

• If a single other indicator is selected, then we would get dual y-axes, like the first screenshot below.
• If multiple other indicators are selected, then we would get signal values scaled to have the same min and max over the observed range, like the second screenshot below.
• Moving your cursor over the time series would show all values for all signals at the given time value, like the third screenshot below.
• To be clear, there would be no other locations shown in faint lines anymore (in the current example, no more national, state, and average-of-neighbors curves). This would disappear as soon as we toggle on "Compare Indicators", which would only show the current location.

As a separate idea, we could have another toggle called "Compare Locations". This would show up, say, on the right-hand side o fetch plot again, right above or below "Compare Indicators". If this were toggled on, then it would allow me to select from any of the locations (that are available for the given indicators). The default selection would be whatever the default is for the faint lines; that is, national, parent state, and average-of-neighbors for the current example.

• I think the y-axis business here would be very simple, we just keep it as is.
• But the lines here are no longer faint, they are all painted fully/normally.
• And the hover tips would be as I suggested above in the "Compare Indicators" mode (shows values for all locations).

[ryantibs]

Few updates: I removed v3.1 because this is quite big and would probably hold up a 3.1 release, and shouldn't.

Also, after speaking with Sam a bit on slack, I think it makes more sense to try this out on the dashboard builder. That will allow us to try it out and see how it works, and see how much we like it.

On the dashboard builder, I think each of these requests: "Compare Indicators" or "Compare Locations" can be enabled simply as allowing the user to select multiple indicators or multiple locations (but not both simultaneously) from the "Add Widget" options.

[sgratzl]

re comparison in dashboard builder:

since the highlights in time series charts are synced you can already do some comparisons: