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3.15 apply a filter on 1D numerical data (a vector)

Problem: suppose we want to apply say an averaging filter on a list of numbers. Say we want to replace each value in the list by the average 3 values around each value (a smoothing filter).

In Mathematica, ListConvolve is used, in Matlab conv() is used.

Mathematica 

data={1,2,7,9,3,4,10,12}; 
filter=(1/3){1,1,1}; 
data[[2;;-2]]=ListConvolve[filter,data]; 
N[data]
 


Out[66]= {1., 
          3.33333, 
          6., 
          6.33333, 
          5.33333, 
          5.66667, 
          8.66667, 
          12.}

 

Matlab 

data   = [1 2 7 9 3 4 10 12]; 
filter = (1/3)*[1 1 1]; 
data(2:end-1) = conv(data,filter,'valid'); 
data'
 


    1.0000 
    3.3333 
    6.0000 
    6.3333 
    5.3333 
    5.6667 
    8.6667 
   12.0000

 

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