ntpviz - Don't plot a line during data absence

Hal Murray hmurray at megapathdsl.net
Sun Oct 23 19:08:40 UTC 2016

jason at azze.org said:
> In the interest of keeping longer technical discussions on the devel list,
> we have this: 


> <gemiller> hmm, some people use up to poll 1024, I could preprocess the plot
> file so that any gap longer than 1024 seconds does not get a connecting
> line.  Sound good?  Or would people prefer to see just dots first? 

If the polling interval is X, there may be up to 8X gaps in peerstats.

I think it helps to avoid the long lines across missing data.

Lines vs points is an interesting tangle.

Lines work well when the data is smooth.  The same data with points turns 
into a fat line if the points are dense.  (I consider the single dot type of 
point to be useless since I can't see an isolated dot on my screen unless I 
know where to look.)

If you have occasional outliers, lines mode draws a line up to that sample 
and back down.  That makes it easy to spot the outliers.  If you have more 
than occasional outliers that turns into a lot of clutter on the screen and 
points mode is probably better.

If the data is not smooth, and the samples are dense, line mode turns into a 
broad swath of up and down lines.  Points mode has the same problem - the 
swath is made up of points rather than line segments.  You can solve the 
problem by spreading things out in X, or Y if in points mode.

Things get more interesting if you try to plot several sets of data that 
mostly overlap.

I haven't found a good way to automate the decision process.  I've been doing 
it by hand.  A config file to guide that might be interesting.  It could also 
specify which graphs to plot and/or what to put on a graph.

These are my opinions.  I hate spam.

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