Re: [Gnuplot-info] Anomalies in Gnuplot (fwd)

[zowie <def...@bo...>]

It looks correctly plotted to me.  

Looking at your .dat file: you’re missing a point on 17-April-2016, then you’ve got two points 
18-April-2016 and 19-April-2016, both with systolic of 146 (correctly plotted on the Y axis 
which goes to 160). Those are correctly rendered as a short horizontal line segment between 
the two data.

After that you’ve got a stay in hospital.

So it looks like your “glitch” isn’t you running home from hospital, it’s you being sick for a day
and breaking the progression.

The gap before 18-April may appear larger because the missing point on 17-April loses you 
*two* line segments: 16-17 and 17-18.  

You might like to plot this chart with histeps or linespoints rather than with lines:  line
plots like this are not as useful for understanding point-by-point progressions of missing or
error-prone data.  For that type of analysis, “histeps” is a better choice: you still get the
eye-pleasing connectivity of “lines”, but a more rigorous and less counterintuitive treatment 
of sampled and missing intervals.

Note that the above does not describe a problem with gnuplot, but rather with the practice of 
drawing plots of noisy (and potentially missing) data by connecting sampled points with straight
lines.

> On Jul 13, 2016, at 5:15 PM, Dave Horsfall <da...@ho...> wrote:
> 
> Am I the only one with these (allegedly minor) problems?
> 
> -- 
> Dave Horsfall DTM (VK2KFU)  "Those who don't understand security will suffer."
> 
> ---------- Forwarded message ----------
> Date: Wed, 1 Jun 2016 10:08:29 +1000 (EST)
> From: Dave Horsfall <da...@ho...>
> To: Gnuplot Mailing List <gnu...@li...>
> Subject: Anomalies in Gnuplot
> 
> Gnuplot 5.0 pl 3, on MacOS 10.11.5
> 
> I'm seeing a couple of glitches in Gnuplot, and I cannot see where I 
> stuffed up.
> 
> Browse over to www.horsfall.org/gptest and view the files therein; they 
> are a cut-down version of a script I use to plot my BP etc (note that my 
> dates use the format d/m/y, as I am not American; later graphs use the 
> more conventional yy/mm/dd, which actually sorts).
> 
> The gap towards the end of April is where I spent a week in hospital, but 
> note the sole dot in the middle; there is no datum for it, and anyway I 
> don't recall dashing home midway through my unintended confinement :-)
> 
> What would be causing it?  It's driving me nuts.
> 
> The other glitch is the datum for 18/4/16 (146), which did not go off the 
> scale but should have (at the time my scale was 0:140, since a BP of over 
> 140 means Trouble), but that's not so important.
> 
> Help, anyone?
> 
> -- 
> Dave Horsfall DTM (VK2KFU)  "Those who don't understand security will suffer."
> 
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