Delete all NaN (empty points) from a numeric wave or a text wave

 
// Handy Function to delete NaNs from TextWaves:
Function DeleteNaNTextwave(W)
Wave /T W
Duplicate /T /O W WwoNaNs
Variable Points = numpnts(WwoNaNs)
InsertPoints Points,1, WwoNaNs // Insert trailing NaN to make loop-break-condition work
Variable i=0, NOP
    Do
    NOP = numpnts(WwoNaNs)
    if((strlen(WwoNaNs [i]) == 0)||(cmpstr("",WwoNaNs [i]) == 0)||(cmpstr("NaN",WwoNaNs [i])==0))
        DeletePoints i, 1, WwoNaNs
        i = 0 // Start over again
    else
    i = i+1
    endif   
    while(strlen(WwoNaNs[NOP])==0) // see above
End
 
// Handy Function to delete NaNs from NumericWaves:
Function DeleteNaNNumWave(W)
Wave W
String OldName = NameofWave(W)
String NewName = OldName+"_woNaNs"
ConvertNumWvToTxtWv(W)
DeleteNaNTextwave(TxtConvert)
ConvertTxtWvToNumWv(WwoNaNs)
Duplicate /O NumConvert $NewName
End
 
// Handy Function to convert numeric waves into text waves
Function ConvertNumWvToTxtWv(W)
Wave W
Variable np = numpnts(W)
Make /T /O /N=(np) TxtConvert
Variable x
for(x=0;x<np;x+=1)
    TxtConvert[x] = num2str(W[x])
endfor
End
 
// Handy Function to convert text waves into numeric waves
Function ConvertTxtWvToNumWv(W)
Wave /T W
Variable np = numpnts(W)
Make /O /N=(np) NumConvert
Variable x
for(x=0;x<np;x+=1)
    NumConvert[x] = str2num(W[x])
endfor
End
This part is pretty inefficient:
Function DeleteNaNTextwave(W)
Wave /T W
Duplicate /T /O W WwoNaNs
Variable Points = numpnts(WwoNaNs)
InsertPoints Points,1, WwoNaNs // Insert trailing NaN to make loop-break-condition work
Variable i=0, NOP
    Do
    NOP = numpnts(WwoNaNs)
    if((strlen(WwoNaNs [i]) == 0)||(cmpstr("",WwoNaNs [i]) == 0)||(cmpstr("NaN",WwoNaNs [i])==0))
        DeletePoints i, 1, WwoNaNs
        i = 0 // Start over again
    else
    i = i+1
    endif   
    while(strlen(WwoNaNs[NOP])==0) // see above
End


You don't need to "start over again" after every point that you've deleted. You could simply call continue:

Function DeleteNaNTextwave(W)
Wave /T W
Duplicate /T /O W WwoNaNs
Variable Points = numpnts(WwoNaNs)
InsertPoints Points,1, WwoNaNs // Insert trailing NaN to make loop-break-condition work
Variable i=0, NOP
    Do
    NOP = numpnts(WwoNaNs)
    if((strlen(WwoNaNs [i]) == 0)||(cmpstr("",WwoNaNs [i]) == 0)||(cmpstr("NaN",WwoNaNs [i])==0))
        DeletePoints i, 1, WwoNaNs
        continue
    else
    i = i+1
    endif   
    while(strlen(WwoNaNs[NOP])==0) // see above
End


Note that this code gives a run time error if #pragma rtGlobals=3 is in effect.

I would recommend writing the function a slightly different way. This iterates in reverse using a For loop and it doesn't call InsertPoints at the beginning. The fewer inserting and deleting of points you do to a text wave, the better off you are, because redimensioning a text wave like that can be slow if the wave is large.

Function DeleteNaNTextwave(W)
    Wave /T W
    Duplicate /T /O W, WwoNaNs
    Variable Points = numpnts(WwoNaNs)
    Variable i=0
    
    For (i = Points - 1; i >= 0; i -= 1)
        if((strlen(WwoNaNs [i]) == 0)||(cmpstr("",WwoNaNs [i]) == 0)||(cmpstr("NaN",WwoNaNs [i])==0))
            DeletePoints i, 1, WwoNaNs
        endif   
    EndFor
End


By the way, I don't understand why you have both (strlen(WwoNaNs [i]) == 0) and (cmpstr("",WwoNaNs [i]) == 0) in your test. I can't think of a situation in which the second would be true but the first would be false.

August 28, 2014 at 06:19 am - Permalink

Another way:  Extract /o W, WwoNaNs, numtype(wtest)==0

Is WaveTransform more efficient?

September 13, 2014 at 05:54 pm - Permalink

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