Modifying Text Files

Could someone experienced in manipulating files help me with a sticky problem? I am trying to take a large, specified number of separate .txt files containing comma-separated data and condense them into one, large file that can be entered into an analysis program in one fell swoop. However, the values from each file need to be appended onto their respective lines to form new columns, rather than just tacked onto the bottom of the file.

Does anyone have a suggestion on how to do this? Sadly, I am not very experienced with C, so you may have to be somewhat patient with me.

Something like

File 1:
London,1
Paris,2

File 2:
London,3
Paris,4

Producing a combined result of
London,1,3
Paris,2,4

Surely, a task made for a computer. :)

I'd need to see a sample of your input files - just something short, not the whole thing, and then what your desired output would be, as well.

Something like what Salem posted, but I would like to see a sample of the actual data and actual result; just a concrete snippet.

How you're identifying "their" respective lines is very important. Please explain in your sample of data you post.

Adak

Quote:

---

Originally Posted by Salem

Something like

File 1:
London,1
Paris,2

File 2:
London,3
Paris,4

Producing a combined result of
London,1,3
Paris,2,4

---

Yes, that's it exactly. Thanks to both of you for replying so quickly. :)

I attatched some of the data. I'm actually not all that familiar with what it means; I'm an undergrad physics student; I ended up being paid to help some graduate students make their analysis more efficient after I talked with one of my physics professors and mentioned that I had "taken a class in C++ once." Much of their explanation of what they were doing is stuff I know virtually nothing about. Anyway, at the moment, they're entering hundreds of files like this into the analysis software one at a time, manually! I know that the leftmost column (analogous to London, Paris) is a bunch of frequencies; that's the part I'm fuzzy on the meaning of. The rest are tiny DC voltages. This all comes from a study of quantum dots.

This would be the result I'm trying to get, if you assume the extra elements on the line come from other files like the original one. I guess, to clarify, what I want to do is take the data on each line of a bunch of files like this one that corresponds with each one of the frequencies and add it on a line of data that begins with that corresponding frequency.

C really isn't the tool for this job.

Perl on the other hand is.

Code:

---

#!/bin/perl -w
use strict;

# A hash containing all the composite lines
my %lines = ();

while ( <> ) {              # for every line of every file
  chomp;s/\r//;            # remove any \n or \r
  if ( /^([0-9]+)(.*)/ ) {  # separate the first number($1) and the rest line($2)
    if ( ! exists $lines{$1} ) {
      $lines{$1} = $1;      # start each new line with the key
    }
    $lines{$1} .= $2;      # append the rest of the line
  }
}

# print all the lines when we've done reading files.
for my $i ( sort keys %lines ) {
  print "$lines{$i}\n";
}

---

Which produces these kinds of results

Code:

---

$ perl foo.pl foo.txt
787500000, -8.07900e+01, -2.14748e+06, -2.14748e+06
787562500, -8.09020e+01, -2.14748e+06, -2.14748e+06
787625000, -8.04260e+01, -2.14748e+06, -2.14748e+06
787687500, -8.05870e+01, -2.14748e+06, -2.14748e+06
787750000, -8.04020e+01, -2.14748e+06, -2.14748e+06

$ perl foo.pl foo.txt foo.txt
787500000, -8.07900e+01, -2.14748e+06, -2.14748e+06, -8.07900e+01, -2.14748e+06, -2.14748e+06
787562500, -8.09020e+01, -2.14748e+06, -2.14748e+06, -8.09020e+01, -2.14748e+06, -2.14748e+06
787625000, -8.04260e+01, -2.14748e+06, -2.14748e+06, -8.04260e+01, -2.14748e+06, -2.14748e+06
787687500, -8.05870e+01, -2.14748e+06, -2.14748e+06, -8.05870e+01, -2.14748e+06, -2.14748e+06
787750000, -8.04020e+01, -2.14748e+06, -2.14748e+06, -8.04020e+01, -2.14748e+06, -2.14748e+06

---