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How to import a single 1D height profile (xz data)

Mitko
2017-08-21
2017-08-25
  • Mitko

    Mitko - 2017-08-21

    Hi!
    I'm trying to import in Gwyddion a single height profile (xz data) that I have in ASCII. The format is simply:
    xxx TAB zzz
    xxx TAB zzz
    ....

    I tried "raw" and "xyz", but with no success so far. I'm grateful for suggestions!

    Thanks!

     
  • Mitko

    Mitko - 2017-08-22

    Thanks!
    I tried that already and I get a nice curve with the right dimensions etc. However, at a first glance, I'm not able to do anything with that curve - no row statistics, for example.

     
  • David Nečas

    David Nečas - 2017-08-25

    I am not sure what is ‘row statistics’. Anyway, all graph functions are in the Graph menu in the toolbox or, equivalently, in the graph right-click menu. Including Statistics.

     
    • Mitko

      Mitko - 2017-08-28

      Thanks! I found that. But what about the "1D statistical functions", like 1D ACF, 1D FFT etc.?

       
      • David Nečas

        David Nečas - 2017-08-28

        These exist only for images. Curves given as X,Z data can have non-equidistant sampling, and while there are some methods for ACF or PSDF estimation for general 1D data, Gwyddion does not implement them -- its focus is image data analysis.

        If the sampling is equidistant you can cheat and import the curve as an image, but it is a bit tricky (and quite a bit of work if you want to do it en masse -- in such case it is better to transform the files to a format which Gwyddion imports as image data):

        • Import the file using Raw data import, selecting Text format, providing the true number of rows, giving the number of columns as 1 and giving the number of fields to skip as 1 (so x values are skipped). You also need to specify the dimension along the abscissa manually as Height (Width does not matter).
        • Rotate it by 90 degrees.
        • Finally, you have to make the image at least 4 pixels high to use the image statistical functions. For this use Scale, disable proportional scaling, keep the number of columns (so that no interpolation is done) and scale it vertically to at least 4 pixel height.
         
        • Mitko

          Mitko - 2017-08-28

          Great! It worked for me. But I wouldn't have found that workaround.

           

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