Does Matlab have a command to make data smoother like the smooth command in IDL?

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For IDL command,

"The SMOOTH function returns a copy of Array smoothed with a boxcar average of the specified width. The result has the same type and dimensions as Array" ( http://idlastro.gsfc.nasa.gov/idl_html_help/SMOOTH.html). The example of the result is following;

The original data

       7.79008      4.15141      7.48622
       1.69548      6.31630      6.84862
       7.00782      2.78159      7.85362
       5.91996     0.659594      5.77286
       8.38353      3.33698      9.03057
       7.64424     0.474168      5.77164
       3.62966      8.94523      4.11056
       9.33464      1.19968      4.66864
       5.79112      3.83709      1.43494

The result data ( IDL> print, smooth(x,3,/edge) )

       5.31274      5.66250      6.01227
       5.21623      5.58725      5.95827
       5.11973      5.51200      5.90428
       5.42783      5.47206      5.51628
       5.41093      5.25468      5.09842
       5.39403      5.03729      4.68056
       5.54293      5.28162      5.02030
       5.60563      4.92210      4.23857
       5.66832      4.56258      3.45685

Thank you in advance.

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Answer 1

Image Analyst on 9 Sep 2012

Open in MATLAB Online

2 votes

Ordinarily I'd do this:

smoothed_m = conv2(m, ones(3)/9, 'same')

but modified to fix any edge effects:

numerator = conv2(m, ones(3), 'same')
denom = conv2(ones(size(m)), ones(3), 'same')
smoothed_m2 = numerator ./ denom

but it doesn't give you the same output values. However I'm not sure how you got those values. For example, let's take the middle value, which is totally not affected by edge effects. You say it's 5.25468 however in MATLAB:

m9 = [...
   5.91996     0.659594      5.77286
       8.38353      3.33698      9.03057
       7.64424     0.474168      5.77164]
averageValue = mean2(m9)
averageValue =
    5.2215