Revision ef6b14b2f1d2b03be461808142e10c2acf118103 authored by Bernd Bischl on 05 July 2018, 11:49:17 UTC, committed by Bernd Bischl on 05 July 2018, 11:49:17 UTC
1 parent 9355659
smote.c
#include "macros.h"
#include "Rmath.h"
SEXP c_smote(SEXP s_x, SEXP s_isnum, SEXP s_nn, SEXP s_res) {
UNPACK_REAL_MATRIX(s_x, x, nrow_x, ncol_x);
int *isnum = LOGICAL(s_isnum);
UNPACK_INT_MATRIX(s_nn, nn, nrow_nn, ncol_nn);
UNPACK_REAL_MATRIX_2(s_res, res, nrow_res);
double lambda;
unsigned int j_sel;
unsigned int j_nn;
unsigned int lev;
GetRNGstate();
for (R_len_t i = 0; i < nrow_res; i++) {
/* select a random minority obs and random neighbor */
j_sel = runif(0, nrow_x);
j_nn = runif(0, ncol_nn);
/* matrix nn contains indexes of ncol_nn nearest neighbors for each minoriy obs (= rows)
as the indexes originate from R they are one-based, so the randomly chosen index has
to be subtracted by one in order to select the right row (j_nn) of zero-based matrix x */
j_nn = nn[j_sel + j_nn * nrow_nn] - 1;
lambda = unif_rand();
for (R_len_t col = 0; col < ncol_x; col++) {
if (isnum[col]) {
/* do convex combination for numerics */
res[i + col * nrow_res] = lambda * x[j_sel + col * nrow_x] + (1 - lambda) * x[j_nn + col * nrow_x];
} else {
/* for factors we sample a level from x1 or x2 */
if (lambda < 0.5)
lev = x[j_sel + col * nrow_x];
else
lev = x[j_nn + col * nrow_x];
res[i + col * nrow_res] = lev;
}
}
}
PutRNGstate();
return s_res;
}
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