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#142 Parallel coordinate plot type

None
closed-accepted
Ethan Merritt
None
5
2013-12-26
2006-06-15
Niklas Elmqvist
No

It would be useful to have a parallel coordinate plot
type in gnuplot. Parallel coordinates are a
multidimensional visualization technique where
coordinate axes are stacked in parallel, allowing for
data with very high dimensionality to be plotted
without having to resort to 3D graphics or even more
complex mappings. Data points become polylines
connecting the values for each of the dimensions.

Example:

http://www.agocg.ac.uk/reports/visual/casestud/brunsdo
n/parallel.htm

Thanks!

Discussion

  • Ethan Merritt
    Ethan Merritt
    2006-06-17

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    I'll look into this post-4.2

    How do you envision specifying the scaling for each
    dimension? Would there be N scaling functions through which
    N columns of data are mapped to generate the respective y
    coordinates? Or can we just assume that the data has been
    appropriately scaled prior to plotting?

     
  • Ethan Merritt
    Ethan Merritt
    2006-06-17

    • assigned_to: nobody --> sfeam
     
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    user_id=13535

    Being a gnuplot novice, I am not 100% sure what you mean.
    For a parallel coordinate diagram, the point is that the
    scaling on each of the axes is independent of the others
    since the units may be totally unrelated (perhaps there is
    a point to allow for uniform scaling for the special case
    when the axes have the same unit to facilitate comparison).

    GGobi is an Open Source application that implements a PC
    visualization--it does not produce vectorized output,
    however. It might be a good reference model:

    http://www.ggobi.org/

     
  • Ethan Merritt
    Ethan Merritt
    2006-06-19

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    "the point is that the scaling on each of the axes is
    independent of the others since the units may be totally
    unrelated"

    Exactly. So the question is, how will one tell gnuplot what
    those N independent scaling functions are? That is, each
    vertical bar (axis) on the plot has endpoint coordinates
    that are unrelated to the others. We need a way to specify
    what those endpoints should be.

    It could be auto-scaled, of course, but this might be a bad
    choice in the presence of outliers. You probably want to
    spread the scale so the the majority of lines are well
    separated even if a few outliers go out of range.

     
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    user_id=13535

    Most interactive visualization tools autoscale the axes.
    Furthermore, tools like GGobi allows you to interactively
    select a specific data record as a center point, i.e. it
    becomes a straight line and the axes are offset
    accordingly.

    But yes, it would be useful to be able to specify scaling
    for each individual axes. I am not sure how exactly to do
    this, something that would fit in with the gnuplot model
    and command syntax, obviously. :)

    For the use I have in mind for gnuplot (10 dimensions of
    discrete/ordinal data, about 30 records), autoscaling
    suffices perfectly.

     
  • Ethan Merritt
    Ethan Merritt
    2013-12-26

    New plot style "with parallelaxes" in version 4.7

     
  • Ethan Merritt
    Ethan Merritt
    2013-12-26

    • status: open --> closed-accepted
    • Group: -->