Statistics code for desktop (and soon mobile)

Berthold Stoeger bstoeger at mail.tuwien.ac.at
Fri Jan 8 15:13:39 PST 2021


Hi Christof,

Thank you for the detailed report. A few short comments in-line.

On Freitag, 8. Jänner 2021 23:25:07 CET Christof Arnosti via subsurface wrote: 
>   * When I select date(yearly) as base variable and buddies as data, bar
>     charts have a yellow warning in the drop down. Why's that?

A bar-chart is not recommended with continuous data. A histogram is preferred. 
However, as you note, the warning icon is not a good UI element.

In case of sparse data I have likewise found bar charts to be more convenient 
than histograms. On the other hand, I see the argument that they can be 
misleading if only a few cups of data are missing.

>   * The trend line does not always appear in the scatter graph. For
>     example, when I select date (no binning) / depth, there is no trend
>     line, except for when I filter out very shallow depths. For water
>     temp over date I get a trend line right away. I'm sure that's
>     correct and there is a statistical reason for this that I'm not
>     aware of.

Indeed, there is a statistical test whether there is a linear regression. 
Willem knows more.

>   * When I select Buddies over Date(yearly), and then grouped vertical
>     bar chart, the bars are oddly spaced. I suspect that for every buddy
>     there is a bar every year, even if the number is zero. This might
>     make sense in some cases (for example water temperature), but in the
>     buddy case it looks weird. Maybe add some "don't show empty bars"
>     option for the grouped bar charts?

I'm not an expert in charts, but I think that this is how grouped bar charts 
should be done(?). In the case of sparse data a stacked chart is probably 
preferred.

>   * Is there some Export functionality planned? For example simple image
>     export of the graph?

Not yet.

>   * For me the Filter GUI seems a bit unintuitive. When there is no
>     constraint present, it's not very obvious that constraints can be
>     added (the button is in an odd place). A change to make it more
>     obvious could be to add a "Constraints" heading below the fulltext
>     search, and move the button there? And maybe also display a "No
>     constraints" text when no constraint is set? I really like the
>     "Filter sets" functionality!

Yes, I also noticed that - especially in the German translation - the filter 
is quite inaccessible.

>   * What I didn't find was an "Average depth" variable, this would maybe
>     also be interesting to add.

I'm not sure if we currently track the average depth. I'm also not sure it is 
very well defined - what about surface intervals. Dirk?

>   * "Dive number" as Base Variable would maybe make sense to show
>     changes over number of dives. This would be interesting for me since
>     I go diving once or maybe twice a year, so when I use non-binned
>     date as base variable, there are basically vertical lines in the
>     scatter plot (see below).

That is trivial to implement and seems like a good idea.

> What would be really nice, but might be complicated to implement, would
> be to have a kind of "Zoom" or "Select" possibility to add constraints.
> For example my Depth over Date Scattergraph looks like this:
> 
> Now to have a look at a single holiday I can add a constraint over a
> range of dates, for example 1.1.2017 to 1.1.2018. This works fine! But
> the cherry on top would be if I could simply drag a rectangle over the
> points in 2017, and set the constraints like this (Sort of a "Zoom into
> range" functionality).

That is an interesting idea. But don't hold your breath. Currently we are 
changing the rendering engine to port the statistics to mobile and this will 
take some time.

Note that there is a "year" filter constraint, which is quicker to use than 
the general date-filter, if that is all the granularity that you need.

Berthold

> On 08.01.21 21:42, Martin de Weger via subsurface wrote:
> > I have played with it a bit, and it looks great. I haven’t looked into
> > it deep enough to say I actually tested it. 
> > 
> >> Op 8 jan. 2021 om 21:33 heeft Dirk Hohndel via subsurface
> >> <subsurface at subsurface-divelog.org> het volgende geschreven:
> >> 
> >> 
> >> 
> >>> On Jan 3, 2021, at 5:17 PM, Dirk Hohndel <dirk at hohndel.org
> >>> 
> >>> <mailto:dirk at hohndel.org>> wrote:
> >>>> On Jan 3, 2021, at 3:44 PM, Dirk Hohndel via subsurface
> >>>> <subsurface at subsurface-divelog.org
> >>>> <mailto:subsurface at subsurface-divelog.org>> wrote:
> >>>> 
> >>>> Right, I didn't test the AppImage. Silly me. I'll add that to my list.
> >>> 
> >>> AppImage is fixed, also Subsurface now reacts more gracefully if the
> >>> QtCharts QML modules can't be found.
> >>> Instead of a crash the statistics chart is simply empty. What we
> >>> really need is a reasonable error message (or alternative disable
> >>> the statistics entry in the menu.
> >>> But this is at least a step in the right direction.
> >>> 
> >>> New AppImage should appear in downloads/test in the next few minutes
> >>> as Subsurface-v4.9.10-235-gc63994f77-x86_64.AppImage
> >>> This one was tested on a couple of different Linux flavors...
> >> 
> >> So we have working binaries for all platforms, but we have heard
> >> basically no feedback on the new statistics feature.
> >> No indication that anyone has tested this, likes it, hates it, has
> >> suggestions.
> >> 
> >> It's really hard to develop in a vacuum. And it's a bit frustrating, too.
> >> 
> >> I know that guilt-tripping people into doing things simply doesn't
> >> work. Berthold, Willem, and I will continue to just work along.
> >> But we sure would appreciate some input. Even if it is just a simple
> >> "this is the best software ever written in the universe"...
> >> 
> >> Thanks and have a great weekend
> >> 
> >> /D
> >> 
> >> 
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> > 
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