Using wave elements in a Tag in a function

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Fri, 08/02/2019 - 02:21 am

I have a wave named w. I have a function that takes w as an input and does a fit on it, then generates w_fit, w_coef and w_sigma.

I draw w_fit on a graph.

Now I want to write a Tag on w_fit using values from w_coef and w_sigma.

Is this right? Is there a neater way, because this feels to me like I am being clumsy.

 

Function fitthething(winput)

    //... a bunch of fitting stuff

    AppendtoGraph $(NameOfWave(winput)+"_fit")

	WAVE tempwave1 = $(NameOfWave(winput)+"_coef")
	WAVE tempwave2 = $(NameOfWave(winput)+"_sigma")
	VARIABLE center = tempwave1[2]
	STRING tempa 
	sprintf tempa,"%0.1f",3.98486*tempwave1[3]
	STRING tempb 
	sprintf tempb,"%0.1f",3.98486*tempwave2[3]
	STRING tagtext = tempa + U+00B1 + tempb 
	Tag $(NameOfWave(winput)+"_fit"), center, tagtext

End

 

This is the general approach that I would take.

You might separate the function that does the tagging from the function that does the fitting, essentially having a DoMyFit(...) function and a TagMyFit(...) function that are called from a master function FitandShow(...). The DoMyFit function can be set to append the fit curve automatically to the graph. All you will need to do is tag that curve. Since you use NameOfWave more than once, define it as string wname = NameofWave(winput). In the same vein, define variable cf = 3.98486 and do sprintf ... cf*tempwave... for clarity.

August 2, 2019 at 06:56 am - Permalink

When you are dealing with existing waves as in this case, it is best to create a wave reference rather than using $<string> repeatedly. This is more readable, easier to debug, and avoids repetition.

Here is how I would write your function:

Function fitthething(wInput)
    Wave wInput
   
    //... a bunch of fitting stuff

    String wInputName = NameOfWave(wInput)
   
    String fitWaveName = wInputName + "_fit"
    Wave fitWave = $fitWaveName
   
    String coefWaveName = wInputName + "_coef"
    Wave coefWave = $coefWaveName
   
    String sigmaWaveName = wInputName + "_sigma"
    Wave sigmaWave = $sigmaWaveName
   
    AppendtoGraph fitWave

    VARIABLE center = coefWave[2]
    STRING tempa
    sprintf tempa,"%0.1f",3.98486*coefWave[3]
    STRING tempb
    sprintf tempb,"%0.1f",3.98486*sigmaWave[3]
    STRING tagtext = tempa + U+00B1 + tempb
    Tag fitWave, center, tagtext
End

When dealing with waves that may or may not exist, use Wave/Z and then WaveExists to test for the wave's existence.

If you are making a wave that may not yet exist, use Make $<string> or Make/O $<string> before making the wave reference.

I recommend, even for experienced Igor programmers who may need a reminder, reviewing this help topic:

DisplayHelpTopic "Accessing Global Variables And Waves"

 

August 2, 2019 at 08:01 am - Permalink

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