Copy x (time) value from one wave to a "blank" wave

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Tue, 02/03/2009 - 03:49 pm

I am trying to figure out if there is a way to take the x/time value from a pre existing wave and copy it over to a given index on another wave, one that has not had a scale set. An example would be:

setX = pnt2x(wave, wave_index ) //gives us the x/time value of this point in wave

From there I would want to try something like

wave2[wave2_index].x = setX //assigns the time value to this point in wave2

Obviously this syntax is wrong, but it gets the idea across of what I am trying to do. Is such an action possible? I am not finding information relating to this in the documentation and am relatively new to Igor (just a few weeks). Thanks for any help.
The X scaling of a wave is stored in the wave as two values, an x0 and a dx. x0 is the X value of point 0 of the wave and dx is the difference in X value from one point to the next.

You can't set the X value of a point independent of the other points. You can only set the x0 and dx properties using the SetScale operation.

For more on X scaling and the idea of a waveform, execute this:

DisplayHelpTopic "The Waveform Model of Data"

If you want to copy the X scaling of one wave to another, you can use CopyScales.

You could also do it using something like this:

Variable x0 = DimOffset(wave1, 0)
Variable dx = DimDelta(wave1, 0)
SetScale/P x x0, dx, wave2


or like this:

Variable x0 = pnt2x(wave1,0)
Variable dx = pnt2x(wave1,1) - pnt2x(wave1,0)
SetScale/P x x0, dx, wave2


If your data is not evenly-spaced then you need to us an XY pair. In this case, you should not set the X scaling of your waves at all. For more on XY data:

DisplayHelpTopic "The XY Model of Data"

February 3, 2009 at 07:19 pm - Permalink