How to remove Plotchart data from memory?

Marcos

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Feb 8, 2012, 8:29:42 AM2/8/12

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Dear,

I want to use Plotchart to plot charts for a data acquisition system
running in the laboratory for several days.

I am afraid that the great volume of data in memory can cause problems
of slowness.

How do I remove the memory data created by plotchart without having to
restart the application.

The command

package forget Plotchart

don't remove the commands of Plotchart

and after the command

namespace delete ::Plotchart

I can not load the package again with

package require Plotchart

Any suggestions?

Thanks,
Marcos

DrS

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Feb 8, 2012, 9:18:21 AM2/8/12

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On 2/8/2012 8:29 AM, Marcos wrote:
> Dear,
>
> I want to use Plotchart to plot charts for a data acquisition system
> running in the laboratory for several days.
>
> I am afraid that the great volume of data in memory can cause problems
> of slowness.
>

Will your chart also keep getting bigger? Probably not. In that case,
you'd probably only want the latest x number of data points. This should
be easy to manage and should not amount to too much memory. With each
new measurement, you just keep a list of the most recent x number of
points to plot.

Or, depending on the specifics, you can display the summary data and not
each individual measurement. Again, your vector size is limited.

DrS

Arjen Markus

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Feb 10, 2012, 7:36:00 AM2/10/12

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In addition to DrS's suggestions, I can add (as author of Plotchart)
that Plotchart itself
does not keep the data in memory - the application is responsible for
that.
A source of memory consumption could be the canvas. To deal with that:
- the "plot" method of an xy-plot (and similarly for other types)
creates individual
canvas items. These might accumulate.
- the "plotlist" method on the other hand creates a limited number of
canvas items,
but these items may have a lot of coordinates. The memory
consumption will be a lot
smaller than for the "plot" method.
- the data items have several labels - both "data" and the data series
they belong to.
You can use that to remove items when they are no longer needed
without redrawing
the plot/chart. Consult the documentation for details.

Regards,

Arjen

Donal K. Fellows

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Feb 10, 2012, 8:58:09 AM2/10/12

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On 10/02/2012 12:36, Arjen Markus wrote:
> A source of memory consumption could be the canvas. To deal with that:
> - the "plot" method of an xy-plot (and similarly for other types)
> creates individual canvas items. These might accumulate.

The item IDs will certainly leak; they're Tk_Uids under the covers.
Reuse if you can.

> - the "plotlist" method on the other hand creates a limited number of
> canvas items, but these items may have a lot of coordinates. The memory
> consumption will be a lot smaller than for the "plot" method.

Yes. Coordinate lists don't leak.

Donal.

Marcos

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Feb 17, 2012, 10:16:49 AM2/17/12

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Thanks for the informations and the indication of the command
plotlist.
Rushed to solve my problem I did not pay attention to the method
plotlist.
Marcos

Arjen Markus

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Feb 19, 2012, 7:41:18 AM2/19/12

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Well, plotlist is a relatively new one :), it is meant for speed, it
was
not designed for minimizing memory usage - that is merely a convenient
consequence.

Regards,

Arjen