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Re: Why does plotting with point labels make plot generation extremely slow?

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On Monday, April 29, 2019 at 7:52:09 AM UTC+1, Ethan Merritt wrote:
> On Sun, 28 Apr 2019 02:36:50 -0700, ciro.santilli wrote:
> 
> > This made me curious, since I wouldn't intuitively expect that just adding point labels would add so much overhead.
> > 
> > In particular if the point labels are hypertext, in which case they don't even show and no placement calculation needs to be done for them.
> 
> Several reasons:
> 
> 1) hypertext labels take fully as much setup and processing as
> non-hypertext labels. The label is written as normal but wrapped in an
> extra bit of code that sets a "visibility" attribute to "off".
> When you mouse over that point the program (actually the qt or wxt
> or browser support libraries) have to figure out which point that is
> and flip the corresponding attribute to "on", then redraw the plot.
> 
> 2) font rendering is slow.  Again this is not gnuplot itself.
> The font rendering is done by the display system 
> (qt/wxt/x11/browser/whatever).
> When you say      plot 'foo' using 1:2:3
> it plots only points or lines, so no font rendering is required.
> As soon as you add "with labels" this changes drastically.
> 
> 3) Actually a bit of the slow label handling may be gnuplot's
> fault if there are a _lot_ of labels, as in your 10^6 label case.
> Gnuplot maintains a singly linked list of labels and walks all the
> way to the end when adding a new one.  For reasonable numbers of
> labels that doesn't matter, but the insertion overhead is O(2) so
> that must eventually hurt.  If there were a legitimate use case
> for a million labels I'm sure that particular bit of overhead could
> be reduced to near zero.  Do you have one?
> 

Thanks all for the reply,

My use case is described in detail at:
https://stats.stackexchange.com/questions/376361/how-to-find-the-sample-points-that-have-statistically-meaningful-large-outlier-r

Basically, I have 10 million multidimensional points, and I do a XY
scatter plot on the two main dimensions of interest.

Then, some points visually stick out, and I want to use information
from all dimensions to understand why, so I need to get a precise ID
for the point, which is what I tried to use labels for.

I ended up resorting to VistIt to solve that one, but that was a
painful experience ;-)

> All that said, I get times of roughly 2.3 minutes for either wxt or
> qt to draw 10^5 labels.  (I didn't try 10^6).
> 
> 	Ethan
> 
> 
> 
> > Generate test data with 1 million lines:
> > 
> >     i=0; while (( $i < 1000000 )); do echo "$i $i $i"; i=$((i + 1)); done > 1m.dat
> > 
> > and here are all the tests that I've tried:
> > 
> >     #!/usr/bin/env gnuplot
> > 
> >     #set terminal png size 1024,1024
> >     #set output "gnuplot.png"
> > 
> >     set terminal canvas mousing
> >     set output "gnuplot.html"
> > 
> >     #set terminal wxt size 1024,768
> > 
> >     #plot "1m.dat" using 1:2
> >     plot "1m.dat" using 1:2:3 with labels hypertext
> > 
> > With all terminal types, the command without "with labels hypertext" works and finishes quickly.
> > 
> > But if I add "with labels hypertext" however, all commands take more than one hour, and I've lost patience to wait for them to finish.
> > 
> > The same goes if I remove "hypertext".
> > 
> > Tested in gnuplot 5.2 patchlevel 2, Ubuntu 18.10.

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Thread

Why does plotting with point labels make plot generation extremely slow? ciro.santilli@gmail.com - 2019-04-28 02:36 -0700
  Re: Why does plotting with point labels make plot generation extremely slow? Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2019-04-28 19:11 +0200
  Re: Why does plotting with point labels make plot generation extremely slow? Ethan Merritt <eamerritt@gmail.com> - 2019-04-29 06:52 +0000
    Re: Why does plotting with point labels make plot generation extremely slow? ciro.santilli@gmail.com - 2019-04-29 01:01 -0700
      Re: Why does plotting with point labels make plot generation extremely slow? Ethan Merritt <eamerritt@gmail.com> - 2019-04-30 01:49 +0000
        Re: Why does plotting with point labels make plot generation extremely slow? ciro.santilli@gmail.com - 2019-04-30 01:17 -0700
          Re: Why does plotting with point labels make plot generation extremely slow? Ethan Merritt <sfeam@users.sf.net> - 2019-04-30 19:06 +0000
            Re: Why does plotting with point labels make plot generation extremely slow? ciro.santilli@gmail.com - 2019-04-30 14:26 -0700

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