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I need some help to smooth some data with awk olny of column 4 and next. This is a data example:


The output should not modify Date;time;Time_ms and print the average of A with the A field of n row before and the A field of n row after. The same should be done for the B, C, D... column. For example if n=1 the second row will be:


Maybe something like this can be a startpoint


{       DATA[(++N)%WIDTH]=$0    }

(N>=WIDTH) {
        for(X=(N+1); X<=(N+WIDTH); X++)

        print V/WIDTH;


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For statistical data processing, R is usually easier to use.

It is easier to read all the data into memory. Awk isn't the greatest language for that (though it is certainly possible). Here's a quickie Python script.

#!/usr/bin/env python
import sys
n = int(sys.argv[1])     # the smooth parameter n must be passed as the first argument to the script
print sys.stdin.readline()  # print the header line
def split_line(line):  # split line into first 3 fields as string, then list of numbers
    fields = line[:-1].split(";")
    return [";".join(fields[:3])] + map(float, fields[3:7])
rows = map(split_line, sys.stdin.readlines())
def avg(i, j):
    return (rows[i-n][j] + rows[i][j] + rows[i+n][j]) / 3
for i in xrange(n, len(rows) - n):
    print ";".join([rows[i][0]] + [str(avg(i, j-2)) for j in xrange(3, 7)])

If your data is really huge, here's a script that I think does what you're asking. It reads 2*n+1 lines, stores the values in prev[2*n] through prev[1] plus $0, then prints the average for the (n+1)th line.

awk -F ';' -v OFS=';' -v n="${1-1}" '
    function avg(i) { return (prev[2*n, i] + prev[n, i] + $i) / 3; }
    NR == 1 { print; next }         # title line: print and skip the rest
    NR >= 2*n+2 {
        # fourth line on: print the average values from the past 3 lines
        # with the labels from the previous line
        print labels[n], avg(4), avg(5), avg(6), avg(7);
        # shift the saved averages by 1 position
        for (i=4; i<=7; i++) {
            for (k=2*n; k>1; k--) prev[k, i] = prev[k-1, i];
            prev[1, i] = $i;
        # save the labels of this line to print in the next round
        for (k=n; k>1; k--) labels[k] = labels[k-1];
        labels[1] = $1 ";" $2 ";" $3;
share|improve this answer
Bonjour @Gilles, I tried you awk script but as reslult I obtain a file that is the copy of the original... no vaerage is made. No errors are showed on terminal. I changed only these two things : FS=OFS=";" RS="\r\n" . Have you tried the script? Is working well with you? – Ludovico Feb 13 '13 at 12:23
@Ludovico Sorry, I made some tweaks in my browser after I'd tested the code. Here are working versions. – Gilles Feb 13 '13 at 12:45
I tried your script in python... Works fine!! Thank you!!! Works fine on the example but fails if there is a different number of column in the input. My input files doesn't have always the same number of column. How Can I calculate the number of culumn and execute the average on column from 4 to last column? The script fails also if one field is empty; Is it possible to consider empty fields as 0? The script in AWK don't work, but maybe I made some mistake... I'll verify – Ludovico Feb 13 '13 at 20:50
up vote 0 down vote accepted

this is the script that I wrote after that I found this

awk 'BEGIN { FS=OFS=";"
           if (max_nf<NF) 
           for(x=1; x<=NF; ++x) 
    END { 
        printf vector[row,1] OFS vector[row,2] OFS vector[row,3]
               for(col=4; col<max_nf; ++col) 
                      printf OFS "Average(" vector[row,col] ")";
              printf ORS      

    for(row=2; row<max_nr; ++row) {
        printf vector[row,1] OFS vector[row,2] OFS vector[row,3]
              for(col=4; col<max_nf; ++col) 
                printf OFS (vector[row,col]+vector[row-1,col]+vector[row+1,col])/3 ;
            printf ORS
        }' File_IN.csv>File_OUT.csv

This script store the csv file a two dimensional array, then print the first line. For the column >4 print average(HEADER). From the second row to the end of file print the first, the second and the third column and the average of column >4. Even if the python script of @gilles works fine I chose this script as answer because uses AWK as asked.

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