The R Project SVN R

/*
 *  R : A Computer Language for Statistical Data Analysis
 *  Copyright (C)       1999  Robert Gentleman, Ross Ihaka and the
 *                            R Development Core Team
 *
 *  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/*
**  SCCS @(#)rowsum.c   4.2 06/30/93
**
** Add up data along rows
**
** Input
**  dim:   integer vector, the #rows and #columns of the matrix
**  na_x:  the value that marks NA's in the X matrix
**  x  :   matrix of data (remember, S uses column major order!)
**  group: the group to which each row belongs
**
** Output:
**  dd[0]: the number of unique groups found
**  x    : rows 1 to dd[0] contain the sums.
*/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

void R_rowsum(int *dim, double *na_x, double *x, double *group)
{
    register int i,j, k;
    int     nrow, ncol, newrow, isna;
    double  tgrp, sum,  dummy, na;

    nrow = dim[0];
    ncol = dim[1];
    na   = *na_x;

    dummy =0;
    for (i=0; i<nrow; i++) if (group[i] < dummy) dummy = group[i];
    dummy = (dummy/2) -1;    /*no group uses this number */

    newrow =0;
    for (i=0; i<nrow; i++) {
    if (group[i] > dummy) {
        tgrp = group[i];
        for (j=0; j<ncol; j++) {
        sum =0;
        isna=0;
        for (k=i; k<nrow; k++)
            if (group[k] == tgrp) {
            if (x[k + j*nrow] == na)  isna=1;
            else              sum += x[k + j*nrow];
            }
        if (isna==1) x[newrow + j*nrow] = na;
        else         x[newrow + j*nrow] = sum;
        }
        for (k=i; k<nrow; k++)
        if (group[k] == tgrp) group[k] = dummy;
        newrow++;
        }
    }
    dim[0] = newrow;
}