Igor - Create a function to make new wave of data

Question

I'm trying to create a function that will take two sets of waves, compare them, and create a third wave based on given parameters.

wave1 is mass data, and has values for every data point. Wave2 is also mass data, but some data points are zero. I need to compare Wave1 and Wave2, and for the data points where wave2 has a non-zero value, the third wave needs to be the difference of Wave1 minus Wave2. so the third wave will have the number of data points that match the number of non-zero data points in wave2.

Answer 1

If I understand correctly, this function will do what you want. It's basic and doesn't check the waves are the same length for example.

Function CompareWaves(w1, w2, result)
    Wave w1,w2
    String result

    Make/O/N=(numpnts(w1)) $result
    Wave resultW = $result
    resultW[] = w1[p] - w2[p]
    resultW[] = (w2[p] == 0) ? resultW[p] : NaN
    WaveTransform zapnans resultW
End

So, if your waves are called foo and bar, and you want the result to be called diff. Call the function using CompareWaves(foo,bar,"diff") .