Re: Simple plotting

[Rob Kewley]

Leeann Liang Fu wrote:
> 
> Hello,
>         I've been poking around quite a bit in the documentation trying to
> find a way to simply plot x vs. y and have the observerswarm display an
> updated plot at each time step.  Everything I've looked at seems to only
> let me plot a statistic over time.  I haven't found a graph class that
> will let me choose the independent variable, they all just use time as the
> independent variable.
>         The closest thing I've found in the archives of this mailing list
> is included below.  Since I didn't find a response to this message, I'm
> guessing that plotting over something other than time can't easily be
> done in Swarm.  I'm hoping that someone will tell me otherwise.
> 
> Thanks,
> Leeann
> 
> > BLTGraph tools suggestion
> >
> > Rick Riolo (address@hidden)
> > Thu, 24 Apr 1997 13:48:36 -0400 (EDT)
> >
> > It occurred to me that if the BLTGraph tools (and friends)
> > were not tied to a Swarm (i.e., didn't automatically assume
> > a Swarm would be running and a getCurrentTime() would work)
> > then those graphs might be generally useful for non-Swarm programs
> > (or for use in Swarm when a clock is not ticking, so to speak...
> > for example to plot some data pre-collected in a file or some
> > such, as a result of a user button action).
> >
> > So...my suggestion is to somehow make the BLTGraph tools
> > not be so tightly tied to the Swarm clock.
> > For example, just as the lines being plotted
> > are set up via specifying methods to call to get values,
> > could the source of the horizontal axis (time)
> > also be controlable by specifying some method?
> >

I used a BLT grach to plot pressure error vs. change in pressure error
in a control application.  The code to create the grapch is below:

  stateGraph = [BLTGraph create: [self getZone]];
  [stateGraph title: "Control State"];
  [stateGraph axisLabelsX: "PE" Y:"CPE"];
  [stateGraph pack];

  stateElement = [stateGraph createElement];
  [stateElement setLabel: "State"];
  
When I wanted to add a new data point with values PE and cpe, I execute
the line below.  This draws a line from data point to data point which
plots the state trajectory for the control system in two dimensions.

  [stateElement addX: PE Y: cpe];

The functionality for this is documented under BLTGraph and GraphElement
in the tkobjc library swarm documentation.

Rob Kewley

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