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/*
 *  R : A Computer Language for Statistical Data Analysis
 *  Copyright (C) 1995, 1996  Robert Gentleman and Ross Ihaka
 *  Copyright (C) 1998-2001   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
 */

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

#include <Defn.h> /* => Utils.h with the protos from here */
#include <Rmath.h>
            /*--- Part I: Comparison Utilities ---*/

static int icmp(int x, int y, Rboolean nalast)
{
    if (x == NA_INTEGER)return nalast?1:-1;
    if (y == NA_INTEGER)return nalast?-1:1;
    if (x < y)      return -1;
    if (x > y)      return 1;
    return 0;
}

static int rcmp(double x, double y, Rboolean nalast)
{
    if (ISNAN(x))   return nalast?1:-1;
    if (ISNAN(y))   return nalast?-1:1;
    if (x < y)      return -1;
    if (x > y)      return 1;
    return 0;
}

static int ccmp(Rcomplex x, Rcomplex y, Rboolean nalast)
{
                /* compare real parts */
    if (ISNAN(x.r)) return nalast?1:-1;
    if (ISNAN(y.r)) return nalast?-1:1;
    if (x.r < y.r)  return -1;
    if (x.r > y.r)  return 1;
                /* compare complex parts */
    if (ISNAN(x.i)) return nalast?1:-1;
    if (ISNAN(y.i)) return nalast?-1:1;
    if (x.i < y.i)  return -1;
    if (x.i > y.i)  return 1;

    return 0;       /* equal */
}

static int scmp(SEXP x, SEXP y, Rboolean nalast)
{
#ifdef HAVE_STRCOLL
    return strcoll(CHAR(x), CHAR(y));
#else
    return strcmp(CHAR(x), CHAR(y));
#endif
}

Rboolean isUnsorted(SEXP x)
{
    int n, i;

    if (!isVectorAtomic(x))
    error("only atomic vectors can be tested to be sorted");
    n = LENGTH(x);
    if(n >= 2)
    switch (TYPEOF(x)) {

        /* NOTE: x must have no NAs {is.na(.) in R};
           hence be faster than `rcmp()', `icmp()' for these two cases */

    case LGLSXP:
    case INTSXP:
        for(i = 0; i+1 < n ; i++)
        if(INTEGER(x)[i] > INTEGER(x)[i+1])
            return TRUE;
        break;
    case REALSXP:
        for(i = 0; i+1 < n ; i++)
        if(REAL(x)[i] > REAL(x)[i+1])
            return TRUE;
        break;
    case CPLXSXP:
        for(i = 0; i+1 < n ; i++)
        if(ccmp(COMPLEX(x)[i], COMPLEX(x)[i+1], TRUE) > 0)
            return TRUE;
        break;
    case STRSXP:
        for(i = 0; i+1 < n ; i++)
        if(scmp(STRING_ELT(x, i ),
            STRING_ELT(x,i+1), TRUE) > 0)
            return TRUE;
        break;
    default:
        error("unknown atomic type in isUnsorted() -- should not happen");
    }
    return FALSE;/* sorted */
}

SEXP do_isunsorted(SEXP call, SEXP op, SEXP args, SEXP rho)
{
    SEXP ans;

    checkArity(op, args);
    ans = allocVector(LGLSXP, 1);
    LOGICAL(ans)[0] = isUnsorted(CAR(args));
    return ans;
}


            /*--- Part II: Complete (non-partial) Sorting ---*/


/* SHELLsort -- corrected from R. Sedgewick `Algorithms in C'
 *      (version of BDR's lqs():*/
#define sort_body                   \
    Rboolean nalast=TRUE;               \
    int i, j, h;                    \
                            \
    for (h = 1; h <= n / 9; h = 3 * h + 1);     \
    for (; h > 0; h /= 3)               \
    for (i = h; i < n; i++) {           \
        v = x[i];                   \
        j = i;                  \
        while (j >= h && TYPE_CMP(x[j - h], v, nalast) > 0) \
         { x[j] = x[j - h]; j -= h; }       \
        x[j] = v;                   \
    }

void R_isort(int *x, int n)
{
    int v;
#define TYPE_CMP icmp
    sort_body
#undef TYPE_CMP
}

void R_rsort(double *x, int n)
{
    double v;
#define TYPE_CMP rcmp
    sort_body
#undef TYPE_CMP
}

void R_csort(Rcomplex *x, int n)
{
    Rcomplex v;
#define TYPE_CMP ccmp
    sort_body
#undef TYPE_CMP
}


void ssort(SEXP *x, int n)
{
    SEXP v;
#define TYPE_CMP scmp
    sort_body
#undef TYPE_CMP
}

void rsort_with_index(double *x, int *indx, int n)
{
    double v;
    int i, j, h, iv;

    for (h = 1; h <= n / 9; h = 3 * h + 1);
    for (; h > 0; h /= 3)
    for (i = h; i < n; i++) {
        v = x[i]; iv = indx[i];
        j = i;
        while (j >= h && rcmp(x[j - h], v, TRUE) > 0)
         { x[j] = x[j - h]; indx[j] = indx[j-h]; j -= h; }
        x[j] = v; indx[j] = iv;
    }
}

void revsort(double *a, int *ib, int n)
{
/* Sort a[] into descending order by "heapsort";
 * sort ib[] alongside;
 * if initially, ib[] = 1...n, it will contain the permutation finally
 */

    int l, j, ir, i;
    double ra;
    int ii;

    if (n <= 1) return;

    a--; ib--;

    l = (n >> 1) + 1;
    ir = n;

    for (;;) {
    if (l > 1) {
        l = l - 1;
        ra = a[l];
        ii = ib[l];
    }
    else {
        ra = a[ir];
        ii = ib[ir];
        a[ir] = a[1];
        ib[ir] = ib[1];
        if (--ir == 1) {
        a[1] = ra;
        ib[1] = ii;
        return;
        }
    }
    i = l;
    j = l << 1;
    while (j <= ir) {
        if (j < ir && a[j] > a[j + 1]) ++j;
        if (ra > a[j]) {
        a[i] = a[j];
        ib[i] = ib[j];
        j += (i = j);
        }
        else
        j = ir + 1;
    }
    a[i] = ra;
    ib[i] = ii;
    }
}

void sortVector(SEXP s)
{
    int n = LENGTH(s);
    if (n >= 2 && isUnsorted(s))
    switch (TYPEOF(s)) {
    case LGLSXP:
    case INTSXP:
        R_isort(INTEGER(s), n);
        break;
    case REALSXP:
        R_rsort(REAL(s), n);
        break;
    case CPLXSXP:
        R_csort(COMPLEX(s), n);
        break;
    case STRSXP:
        ssort(STRING_PTR(s), n);
        break;
    }
}

SEXP do_sort(SEXP call, SEXP op, SEXP args, SEXP rho)
{
    SEXP ans;

    checkArity(op, args);

    if(CAR(args) == R_NilValue) return R_NilValue;
    if(!isVectorAtomic(CAR(args)))
    errorcall(call, "only atomic vectors can be sorted");
    if (isUnsorted(CAR(args))) { /* do not duplicate if sorted */
    ans = duplicate(CAR(args));
    sortVector(ans);
    return(ans);
    }
    else return(CAR(args));
}

            /*--- Part III: Partial Sorting ---*/

/*
   Partial sort so that x[k] is in the correct place, smaller to left,
   larger to right

   NOTA BENE:  k < n  required, and *not* checked here but in do_psort();
           -----  infinite loop possible otherwise!
 */
#define psort_body                      \
    Rboolean nalast=TRUE;                   \
    int L, R, i, j;                     \
                                \
    for (L = 0, R = n - 1; L < R; ) {               \
    v = x[k];                       \
    for(i = L, j = R; i <= j;) {                \
        while (TYPE_CMP(x[i], v, nalast) < 0) i++;          \
        while (TYPE_CMP(v, x[j], nalast) < 0) j--;          \
        if (i <= j) { w = x[i]; x[i++] = x[j]; x[j--] = w; }\
    }                           \
    if (j < k) L = i;                   \
    if (k < i) R = j;                   \
    }


void iPsort(int *x, int n, int k)
{
    int v, w;
#define TYPE_CMP icmp
    psort_body
#undef TYPE_CMP
}

void rPsort(double *x, int n, int k)
{
    double v, w;
#define TYPE_CMP rcmp
    psort_body
#undef TYPE_CMP
}

void cPsort(Rcomplex *x, int n, int k)
{
    Rcomplex v, w;
#define TYPE_CMP ccmp
    psort_body
#undef TYPE_CMP
}


static void sPsort(SEXP *x, int n, int k)
{
    SEXP v, w;
#define TYPE_CMP scmp
    psort_body
#undef TYPE_CMP
}

static void Psort(SEXP x, int k)
{
    switch (TYPEOF(x)) {
    case LGLSXP:
    case INTSXP:
    iPsort(INTEGER(x), LENGTH(x), k);
    break;
    case REALSXP:
    rPsort(REAL(x), LENGTH(x), k);
    break;
    case CPLXSXP:
    cPsort(COMPLEX(x), LENGTH(x), k);
    break;
    case STRSXP:
    sPsort(STRING_PTR(x), LENGTH(x), k);
    break;
    }
}

/* FUNCTION psort(x, indices) */
SEXP do_psort(SEXP call, SEXP op, SEXP args, SEXP rho)
{
    int i, k, n;
    int *l;
    checkArity(op, args);

    if (!isVector(CAR(args)))
    errorcall(call,"only vectors can be sorted");
    n = LENGTH(CAR(args));
    SETCADR(args, coerceVector(CADR(args), INTSXP));
    l = INTEGER(CADR(args));
    k = LENGTH(CADR(args));
    for (i = 0; i < k; i++) {
    if (l[i] == NA_INTEGER)
        errorcall(call,"NA index");
    if (l[i] < 1 || l[i] > n)
        errorcall(call,"index %d outside bounds", l[i]);
    }
    SETCAR(args, duplicate(CAR(args)));
    for (i = 0; i < k; i++)
    Psort(CAR(args), l[i] - 1);
    return CAR(args);
}


            /*--- Part IV : Rank & Order ---*/

static int equal(int i, int j, SEXP x, Rboolean nalast)
{
    int c=-1;

    switch (TYPEOF(x)) {
    case LGLSXP:
    case INTSXP:
    c = icmp(INTEGER(x)[i], INTEGER(x)[j], nalast);
    break;
    case REALSXP:
    c = rcmp(REAL(x)[i], REAL(x)[j], nalast);
    break;
    case CPLXSXP:
    c = ccmp(COMPLEX(x)[i], COMPLEX(x)[j], nalast);
    break;
    case STRSXP:
    c = scmp(STRING_ELT(x, i), STRING_ELT(x, j), nalast);
    break;
    }
    if (c == 0)
    return 1;
    return 0;
}

static int greater(int i, int j, SEXP x, Rboolean nalast)
{
    int c=-1;

    switch (TYPEOF(x)) {
    case LGLSXP:
    case INTSXP:
    c = icmp(INTEGER(x)[i], INTEGER(x)[j], nalast);
    break;
    case REALSXP:
    c = rcmp(REAL(x)[i], REAL(x)[j], nalast);
    break;
    case CPLXSXP:
    c = ccmp(COMPLEX(x)[i], COMPLEX(x)[j], nalast);
    break;
    case STRSXP:
    c = scmp(STRING_ELT(x, i), STRING_ELT(x, j), nalast);
    break;
    }
    if (c > 0)
    return 1;
    return 0;
}

/* listgreater(): used as greater_sub in orderVector() in do_order(...) */
static int listgreater(int i, int j, SEXP key, Rboolean nalast)
{
    SEXP x;
    int c=-1;

    while (key != R_NilValue) {
    x = CAR(key);
    switch (TYPEOF(x)) {
    case LGLSXP:
    case INTSXP:
        c = icmp(INTEGER(x)[i], INTEGER(x)[j], nalast);
        break;
    case REALSXP:
        c = rcmp(REAL(x)[i], REAL(x)[j], nalast);
        break;
    case CPLXSXP:
        c = ccmp(COMPLEX(x)[i], COMPLEX(x)[j], nalast);
        break;
    case STRSXP:
        c = scmp(STRING_ELT(x, i), STRING_ELT(x, j), nalast);
        break;
    }
    if (c > 0)
        return 1;
    if (c < 0)
        return 0;
    key = CDR(key);
    }
    if (c==0 && i<j)
    return 0;
    return 1;
}

static void orderVector(int *indx, int n, SEXP key, Rboolean nalast,
            int greater_sub())
{
    int i, j, h;
    int itmp;

    h = 1;
    do {
    h = 3 * h + 1;
    } while (h <= n);

    do {
    h = h / 3;
    for (i = h; i < n; i++) {
        itmp = indx[i];
        j = i;
        while (greater_sub(indx[j - h], itmp, key, nalast)) {
        indx[j] = indx[j - h];
        j = j - h;
        if (j < h)
            goto next_h;
        }
    next_h: indx[j] = itmp;
    }
    }
    while (h != 1);
}

/* FUNCTION order(...) */
SEXP do_order(SEXP call, SEXP op, SEXP args, SEXP rho)
{
    SEXP ap, ans;
    int i, n = -1, narg = 0;
    Rboolean nalast;

    nalast = asLogical(CAR(args));
    if(nalast == NA_LOGICAL)
    error("`na.last' is invalid");
    args = CDR(args);
    if (args == R_NilValue)
    return R_NilValue;

    if (isVector(CAR(args)))
    n = LENGTH(CAR(args));
    for (ap = args; ap != R_NilValue; ap = CDR(ap)) {
    if (!isVector(CAR(ap)))
        errorcall(call, "Argument %d is not a vector", ++narg);
    if (LENGTH(CAR(ap)) != n)
        errorcall(call, "Argument lengths differ");
    }
    ans = allocVector(INTSXP, n);
    if (n != 0) {
    for (i = 0; i < n; i++)
        INTEGER(ans)[i] = i;
    orderVector(INTEGER(ans), n, args, nalast, listgreater);
    for (i = 0; i < n; i++)
        INTEGER(ans)[i] += 1;
    }
    return ans;
}

/* FUNCTION: rank(x) */
SEXP do_rank(SEXP call, SEXP op, SEXP args, SEXP rho)
{
    SEXP rank, indx, x;
    int *in;
    double *rk;
    int i, j, k, n;

    checkArity(op, args);
    if (args == R_NilValue)
    return R_NilValue;
    x = CAR(args);
    if (!isVector(x))
    errorcall(call, "Argument is not a vector");
    n = LENGTH(x);
    PROTECT(indx = allocVector(INTSXP, n));
    PROTECT(rank = allocVector(REALSXP, n));
    UNPROTECT(2);
    if (n > 0) {
    in = INTEGER(indx);
    rk = REAL(rank);
    for (i = 0; i < n; i++)
        in[i] = i;
    orderVector(in, n, x, TRUE, greater);
    i = 0;
    while (i < n) {
        j = i;
        while ((j < n - 1) && equal(in[j], in[j + 1], x, TRUE))
        j++;
        if (i != j) {
        for (k = i; k <= j; k++)
            rk[in[k]] = (i + j + 2) / 2.0;
        }
        else
        rk[in[i]] = i + 1;
        i = j + 1;
    }
    }
    return rank;
}