trim curve
Altair EmployeeHi,
im looking for a function to trim a curve. The goal is to create a new curve in a different plot, that represents only a portion of the original curve vectors. Further goal is to keep the right hand trimming point variable, meaning that i want to trim the curve on the right hand side not at a fixed x-value, but by meeting the criterion: 'trim at location where the y-value becomes zero' (occurs only once in every curve). This should also account for the case i reload the session containing the trim operation, but with varying curve values. Left hand trimming point may be a fixed x-value.
I already tried:
1) the trim function: problem is, that right hand trimming point is not variable -> not workable
2) macro Cut below limit: problem is, that after the limit, the newly created curve is extended by a horizontal line -> not workable
Is there a function like this?
Florian
Answers
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Hi Florian,
Can you try with the modify curve option, where user can trim the data outside of the selected range.
A tutorial, HG-1020: Modifying Plots, is also available in the Help Menu which shows about the various options available for editing curves.
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Hi George,
as i wrote, that option (it's what i meant by 'trim function' ) doesn't work for me because the right hand trimming point is not variable, but is fixed to a certain x-value. I want the x-value to vary, accordingly to the value y = 0
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Hi Florian
As a workaround, using coordinate info option you can find the x-coordinate value where the y coordinate value becomes zero. And you can provide these values (0 to _) in the 'From' 'To' options in the range thereby you can trim the curve within the range. Both the trimmings points are variable, please see the image attached.
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Hi,
problem is, i want to automate the process.
Meaning that i want to save the trimming operation of the curve in a session. By relaoding this session, the trimming should automatically happen for a new curve (which i read in with the same session), where the y=0-point of this new curve can slightly differ from the previous curve.
So, if one used the suggestion in your last post:
When reloading the session with a new curve, the trimming operation would not hit the right x-value because the y=0 abscissa value has changed. But the x-value of the trimming should change according to the new curve.
Could you provide another solution?
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Hi Florian,
It is possible to automate this process. As per the user requirements customization is possible using Tcl/Tk scripting.
Please refer Reference Guide which describes about Tcl/Tk scripting commands.
Or,
You can consult your local Altair team.
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Hi Florian,
One of my colleague suggested to try Hypermath by creating own function.
I have an example from HyperMath that takes the data only after a certain threshold is reached (for example, I want the force history after the displacement goes over 5).
function trimXbasedOnY(x,y,value)
n,index = ZeroCrossings(y-value)
if (n == 0 ) then
x_cut = []
else
x_cut = x[[index[1]+1:Length(x)]]
end
return x_cut
end
You could create something similar.
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