[Kst] stripchart question

Barth Netterfield netterfield at astro.utoronto.ca
Fri Nov 4 15:53:51 CET 2005


Stripcharts were the first use of kst.

In the 'Data Range' widget, (the data range widget is in any dialog where you 
are specifying a range of points to read) select 'Count from end' and then 
put, eg, 1000 in the 'Range' entry.  Then the last 1000 points of the file 
will be plotted.  If new data is added to the end of the file, the plot will 
be updated and the plot will move to the left as requested.  

Similarly, you can just hit the 'Read from end' icon on the tool bar to put 
all plots into 'count from mode'.

Similarly, imagine 'data.dat' is an ascii file with data being appended to the 
end.  From the command line, you can, eg:

kst -y 1 -y 2 -m 1 -n 1000 data.dat

to plot the last 1000 points in stripchart mode of col 1 and col 2 of data.dat

In the menu under 'Setting->Configure Kst' you can change 'Plot update timer:' 
to set how often kst polls the file to see if new data has arrived.  300ms is 
a good value here.

Does this help?

cbn

On November 4, 2005 12:30 am, Taco Walstra wrote:
> Hi,
> I need a stripchart for plotting data from a realtime application. Perhaps
> you can point me if kst can be easily configured in some way to handle
> this. I need several plots in kst, the number is however variable and
> changes during operation. I have looked at the dcop interface, but
> unfortunately almost no information is available for several functions.
> It's possible to start plots from a Qt application of course, but it needs
> a lot of programming for shifting the complete datavector to the left to
> have a stripchart I presume. Has anybody done such thing? Is the java
> scripting a better way of handling this and if yes how?
> Taco Walstra
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> Kst at kde.org
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