# $Id: joinup.awk,v 1.1 2002-04-12 16:39:57 jan Exp $
#
# Copyright (C) 1999, 2001 by Jan-Oliver Wagner
# 
#    This program is free software; you can redistribute it and/or
#   modify it under the terms of the GNU General Public License
#   as published by the Free Software Foundation; either version 2
#   of the License, or (at your option) any later version.
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program; if not, write to the Free Software
#   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
#
# DESCRIPTION:
# This script reads in files with two columns and joins
# the values of the second column to the previous line if
# the value of the first column is the same.
# Sample:
# 1,3	->	1,3 5
# 1,5		2,3
# 2,3		3,5 8
# 3,5
# 3,8

BEGIN	{
	FS = ","
	from = -1
	to_list = ""
	}

	{
	if (from == $1) {
		to_list = sprintf("%s %s", to_list, $2)
	} else {
		if (from != -1) printf("%d,%s\n", from, to_list)
		from = $1
		to_list = $2
	}
	}

END	{ 
	if (from != -1) printf("%d,%s\n", from, to_list)
	}