Re: [gentoo-user] [OT] - command line read *.csv & create new file

[Etaoin Shrdlu <shrdlu@unlimitedmail.org>]

On Sunday 22 February 2009, 23:28, Mark Knecht wrote:

> > <concatenation of attributes of lines 1..n> <result of line n>
> > <concatenation of attributes of lines 2..n+1> <result of line n+1>
> > <concatenation of attributes of lines 3..n+2> <result of line n+1>
> > <concatenation of attributes of lines 4..n+3> <result of line n+1>
>
> The above diagram is correct when the lines chosen is 3. I suspect
> that I might chose 10 or 15 lines once I get real data and do some
> testing but that was harder to show in this email. A good design for
> me would be a single variable I could set. Once a value is chosen I
> want to process every line in the input file the same way. I don't use
> 5 lines sometimes and 10 lines other times. In a given file it's
> always the same number of lines.

Ok, try this for a start:

BEGIN { FS=OFS=","}

{
  r=$NF;NF--
  for(i=1;i<n;i++){
    s[i]=s[i+1]
    if(NR>=n)printf "%s%s",s[i],OFS
  }
  s[n]=$0;if(NR>=n)printf "%s,%s\n", s[n],r
}

Save the above code in a file (eg, program.awk) and run it with

awk -v n=3 -f program.awk datafile.csv

where the "n=3" part is to  be replaced with the actual number of lines 
you want to group (eg, n=5, n=4, etc.)

With your sample input and n=3, the above awk program produces the output 
you show.