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datawiz.c

/* 
 *  gretl -- Gnu Regression, Econometrics and Time-series Library
 *  Copyright (C) 2001 Allin Cottrell and Riccardo "Jack" Lucchetti
 * 
 *  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 3 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, see <http://www.gnu.org/licenses/>.
 * 
 */

#include "gretl.h"
#include "dlgutils.h"
#include "dialogs.h"
#include "ssheet.h"
#include "menustate.h"
#include "obsbutton.h"
#include "session.h"
#include "toolbar.h"
#include "datawiz.h"

#include "gretl_panel.h"

#define DWDEBUG 0

#define PD_SPECIAL -1

#define known_panel(p) (p->structure == STACKED_CROSS_SECTION || \
                        p->structure == STACKED_TIME_SERIES)

#define any_panel(p) (p->structure == STACKED_CROSS_SECTION || \
                      p->structure == STACKED_TIME_SERIES || \
                      p->structure == PANEL_UNKNOWN)

#define time_series(p) (p->structure == TIME_SERIES || \
                        p->structure == SPECIAL_TIME_SERIES)

/* identifiers for steps in the process of setting
   dataset structure */
enum {
    DW_SET_TYPE = 0,
    DW_TS_FREQUENCY,
    DW_WEEKLY_SELECT,
    DW_STARTING_OBS,
    DW_PANEL_MODE,
    DW_PANEL_SIZE,
    DW_PANEL_VARS,
    DW_CONFIRM
};

enum {
    DW_FORWARD = 0,
    DW_BACK    = 1
};

/* flags that may be set on the dataset options structure */
enum {
    DW_CREATE     = 1 << 0,
    DW_DROPMISS   = 1 << 1,
    DW_N_PRIME    = 1 << 2,
    DW_VLIST_DONE = 1 << 3,
    DW_NP_DONE    = 1 << 4,
    DW_NO_PANEL   = 1 << 5,
    DW_SSHEET     = 1 << 6
};

#define dw_n_is_prime(o) (o->flags & DW_N_PRIME)
#define dw_vlist_done(o) (o->flags & DW_VLIST_DONE)

typedef struct dw_opts_ dw_opts;

struct dw_opts_ {
    gretlopt flags;     /* state bit-flags */
    int n_radios;       /* number of radio-button options */
    int deflt;          /* default setting for current radio variable */ 
    int plf;            /* panel: least factor > 1 of # of observations */
    int uid;            /* panel: ID number of "unit" variable */
    int tid;            /* panel: ID number of "period" variable */
    int *setvar;        /* pointer to variable currently being set */
    int *extra;         /* additional pointer to int variable */
    GtkWidget *spinner; /* used for setting starting observation */
    GList *vlist;       /* panel: list of candidates for uid, tid */
};

static const char *wizcode_string (int code)
{
    const char *titles[] = {
      N_("Structure of dataset"),
      N_("Time series frequency"),
      N_("Daily date to represent week"),
      N_("Starting observation"),
      N_("Panel data organization"),
      N_("Panel structure"),
      N_("Panel index variables"),
      N_("Confirm dataset structure")
    };

    if (code <= DW_CONFIRM) {
      return titles[code];
    } else {
      return "";
    }
}

static int translate_panel_vars (dw_opts *opts, int *uv, int *tv);

/* initialize the "dummy" DATAINFO structure dwinfo, based
   on the current data info */

static void dwinfo_init (DATAINFO *dwinfo)
{
    dwinfo->pd = datainfo->pd;
    dwinfo->structure = datainfo->structure;

    dwinfo->n = datainfo->n;
    strcpy(dwinfo->stobs, datainfo->stobs);
    strcpy(dwinfo->endobs, datainfo->endobs);
    dwinfo->sd0 = datainfo->sd0;

#if DWDEBUG
    fprintf(stderr, "dwinfo_init:\n"
          " pd=%d, structure=%d, sd0=%g, stobs='%s', endobs='%s'\n",
          dwinfo->pd, dwinfo->structure, dwinfo->sd0,
          dwinfo->stobs, dwinfo->endobs);
#endif
}

/* for the case where the structure wizard is being used
   to create a new dataset */

static void prep_spreadsheet (GtkWidget *widget, dialog_t *dlg) 
{
    const gchar *buf;
    int t;

    buf = edit_dialog_get_text(dlg);

    if (buf == NULL || gui_validate_varname(buf, GRETL_TYPE_SERIES)) {
      return;
    }

    datainfo->varname[1][0] = 0;
    strncat(datainfo->varname[1], buf, VNAMELEN - 1);

    close_dialog(dlg);

    /* blank out the auto "index" variable */
    for (t=0; t<datainfo->n; t++) {
      Z[1][t] = NADBL;
    }
    *(VARLABEL(datainfo, 1)) = 0;

    show_spreadsheet(SHEET_NEW_DATASET);
}

static void maybe_start_editing (void)
{
    int cancel = 0;

    edit_dialog(_("gretl: name variable"), 
            _("Enter name for first variable\n"
              "(max. 15 characters)"),
            NULL, prep_spreadsheet, NULL, 
            CREATE_DATASET, VARCLICK_NONE, 
            &cancel);

    if (cancel) {
      /* accept the default blank dataset */
      register_data(NULLDATA_STARTED);
    } 
}

/* for balanced panel checking */

static int least_factor (int n)
{
    int flim = n;
    int prime = 1;
    int factor;
    
    if (n % 2 == 0) {
      return 2;
    }

    for (factor = 3; factor < flim; factor += 2) {
      if (n % factor == 0) {
          prime = 0;
          break;
      } else {
          flim = n / factor;
      }
    }

#if DWDEBUG
    fprintf(stderr, "least factor: prime = %d, factor = %d\n",
          prime, factor);
#endif

    return (prime)? 1 : factor;
}

/* figure out if the dataset contains a prime number of
   observations */

static void eval_n_is_prime (dw_opts *opts)
{
    if (opts->flags & DW_NP_DONE) {
      return;
    }

    opts->plf = least_factor(datainfo->n);

    if (opts->plf == 1) {
      opts->flags |= DW_N_PRIME;
      if (opts->flags & DW_CREATE) {
          opts->flags |= DW_NO_PANEL;
      }
    } else {
      opts->flags &= ~DW_N_PRIME;
    }

    opts->flags |= DW_NP_DONE;
}

static void maybe_unrestrict_dataset (void)
{
    if (complex_subsampled()) {
      maybe_free_full_dataset(datainfo);
      if (datainfo->t1 == 0 && 
          datainfo->t2 == datainfo->n - 1) {
          restore_sample_state(FALSE);
      }
    }
}

/* respond to the "Apply" button in the wizard */

static int dwiz_make_changes (DATAINFO *dwinfo, dw_opts *opts,
                        GtkWidget *dlg)
{
    char setline[32];
    char record[128];
    gretlopt opt = OPT_NONE;
    int create = (opts->flags & DW_CREATE);
    int delmiss = (opts->flags & DW_DROPMISS);
    int delete_markers = 0;
    int err = 0;

    *record = '\0';

    /* preliminaries */
    if (time_series(dwinfo)) {
      ntodate_full(dwinfo->stobs, dwinfo->t1, dwinfo);
    } else if (known_panel(dwinfo)) {
      if (!dataset_is_panel(datainfo)) {
          /* Turning a subset of a non-panel dataset into a panel:
             this change will be irreversible */
          maybe_unrestrict_dataset();
      }
    }

    /* special: reorganizing dataset based on panel index vars */
    if (dwinfo->structure == PANEL_UNKNOWN) {
      int uv, tv;

      err = translate_panel_vars(opts, &uv, &tv);
      if (!err) {
          err = set_panel_structure_from_vars(uv, tv, Z, datainfo);
      }
      if (!err) {
          sprintf(record, "setobs %s %s --panel-vars",
                datainfo->varname[uv], datainfo->varname[tv]);
      }
      goto finalize;
    }

    /* check for nothing to be done */
    if (dwinfo->structure == datainfo->structure &&
      dwinfo->pd == datainfo->pd &&
      strcmp(dwinfo->stobs, datainfo->stobs) == 0) {
      if (create || delmiss) {
          /* recording? */
          goto finalize;
      } else {
          infobox(_("No changes were made"));
          return 0;
      }
    }

    /* if converting to time series, we probably don't want to
       retain any original observation-marker strings */
    if (dwinfo->structure == TIME_SERIES && 
      datainfo->markers && !delmiss) {
      delete_markers = 1;
    }

    /* handle panel structure */
    if (known_panel(dwinfo)) {
      int nunits = dwinfo->t1;
      int nperiods = datainfo->n / nunits;

      /* we don't offer a choice of "starting obs" */
      dwinfo->pd = (dwinfo->structure == STACKED_TIME_SERIES)? 
          nperiods : nunits;
      strcpy(dwinfo->stobs, "1.1");
    } 

    /* handle conversion to cross-section */
    if (dwinfo->structure == CROSS_SECTION) {
      strcpy(dwinfo->stobs, "1");
    }

    sprintf(setline, "setobs %d %s", dwinfo->pd, dwinfo->stobs);

    if (dwinfo->structure == TIME_SERIES) {
      opt = OPT_T;
    } else if (dwinfo->structure == STACKED_TIME_SERIES) {
      opt = OPT_S;
    } else if (dwinfo->structure == STACKED_CROSS_SECTION) {
      opt = OPT_C;
    } else if (dwinfo->structure == CROSS_SECTION) {
      opt = OPT_X;
    } else if (dwinfo->structure == SPECIAL_TIME_SERIES) {
      opt = OPT_N;
    }

    err = set_obs(setline, &Z, datainfo, opt);

#if DWDEBUG
    fprintf(stderr, "setline = '%s', opt = %ld; set_obs returned %d\n", 
          setline, opt, err);
#endif

    if (!err) {
      sprintf(record, "%s%s", setline, print_flags(opt, SETOBS));
    }

 finalize:

    if (!err && delmiss) {
      err = dataset_purge_missing_rows(Z, datainfo);
    }

    if (err) {
      gui_errmsg(err);
    } else if (create) {
      if (opts->flags & DW_SSHEET) {
          gtk_widget_hide(dlg);
          maybe_start_editing();
      } else {
          register_data(NULLDATA_STARTED);
      }
    } else {
      if (delete_markers) {
          dataset_destroy_obs_markers(datainfo);
      }
      mark_dataset_as_modified();
    }

    if (!err && *record != '\0') {
      record_command_line(record);
    }

#if DWDEBUG
    fprintf(stderr, "dwiz_make_changes: returning %d\n", err);
#endif

    return err;
}

#define TS_INFO_MAX 10
#define PANEL_INFO_MAX 3

struct freq_info {
    int pd;
    const char *label;
};

struct freq_info ts_info[] = {
    {  1, N_("Annual") },
    {  4, N_("Quarterly") },
    { 12, N_("Monthly") },
    { 52, N_("Weekly") },
    {  5, N_("Daily (5 days)") },
    {  6, N_("Daily (6 days)") },
    {  7, N_("Daily (7 days)") },
    { 24, N_("Hourly") },
    { 10, N_("Decennial") },
    { PD_SPECIAL, N_("Other") },
};

struct panel_info {
    int code;
    const char *label;
};

struct panel_info pan_info[] = {
    { STACKED_TIME_SERIES,   N_("Stacked time series") },
    { STACKED_CROSS_SECTION, N_("Stacked cross sections") },
    { PANEL_UNKNOWN,         N_("Use index variables") }
};

static const char *ts_frequency_string (int pd)
{
    int i;

    for (i=0; i<TS_INFO_MAX; i++) {
      if (ts_info[i].pd == pd) {
          return ts_info[i].label;
      }
    }

    return N_("Non-standard frequency");
}

/* For a step that involves a radio-button choice, figure
   out the default value */

static int dwiz_radio_default (DATAINFO *dwinfo, int step)
{
    int deflt = 1;

#if DWDEBUG
    fprintf(stderr, "radio_default: step=%d, dwinfo->pd=%d, dwinfo->structure=%d\n", 
          step, dwinfo->pd, dwinfo->structure);
#endif

    if (step == DW_SET_TYPE) {
      deflt = dwinfo->structure;
    } else if (step == DW_TS_FREQUENCY) {
      if (dwinfo->structure == SPECIAL_TIME_SERIES) {
          deflt = PD_SPECIAL;
      } else if (dwinfo->pd == 4 || dwinfo->pd == 5 || 
               dwinfo->pd == 6 || dwinfo->pd == 7 ||
               dwinfo->pd == 10 || dwinfo->pd == 12 ||
               dwinfo->pd == 52) {
          deflt = dwinfo->pd;
      } 
    } else if (step == DW_WEEKLY_SELECT) {
      deflt = dwinfo->v;
    } else if (step == DW_PANEL_MODE) { 
      deflt = dwinfo->structure;
    }

#if DWDEBUG
    fprintf(stderr, " returning deflt = %d\n", deflt);
#endif

    return deflt;
}

/* For step @step of the process, figure out the value that
   should be set by clicking radio button i.
*/

static int dwiz_i_to_setval (DATAINFO *dwinfo, int step, int i)
{
    int setval;

    if (step == DW_SET_TYPE && 
      dwinfo->structure == SPECIAL_TIME_SERIES &&
      i == TIME_SERIES) {
      setval = SPECIAL_TIME_SERIES;
    } else if (step == DW_TS_FREQUENCY) {
      setval = (i < TS_INFO_MAX)? ts_info[i].pd : 0;
    } else if (step == DW_PANEL_MODE) {
      setval = (i < PANEL_INFO_MAX)? pan_info[i].code : 0;
    } else {
      setval = i;
    }

    return setval;
}

/* For step @step of the process, figure out the label that
   should be shown alongside radio button i.
*/

static const char *dwiz_radio_strings (int step, int i)
{
    if (step == DW_SET_TYPE) {
      if (i == 0) return N_("Cross-sectional");
      if (i == 1) return N_("Time series");
      if (i == 2) return N_("Panel");
    } else if (step == DW_WEEKLY_SELECT) {
      if (i == 0) return N_("Monday");
      if (i == 1) return N_("Tuesday");
      if (i == 2) return N_("Wednesday");
      if (i == 3) return N_("Thursday");
      if (i == 4) return N_("Friday");
      if (i == 5) return N_("Saturday");
      if (i == 6) return N_("Sunday");
      if (i == 7) return N_("None (don't use dates)");
    } else if (step == DW_TS_FREQUENCY) {
      return ts_info[i].label;
    } else if (step == DW_PANEL_MODE) {
      return pan_info[i].label;
    }

    return "";
}  

static void dwiz_set_radio_opt (GtkWidget *w, dw_opts *opts)
{
    int val = GPOINTER_TO_INT(g_object_get_data(G_OBJECT(w), "action"));

    if (opts->spinner != NULL) {
      if (val == PD_SPECIAL) {
          GtkAdjustment *adj = 
            gtk_spin_button_get_adjustment(GTK_SPIN_BUTTON(opts->spinner));

          gtk_widget_set_sensitive(opts->spinner, TRUE);
          val = (int) adj->value;
          if (opts->extra != NULL) {
            *opts->extra = SPECIAL_TIME_SERIES;
          }
      } else {
          gtk_widget_set_sensitive(opts->spinner, FALSE);
          if (opts->extra != NULL) {
            *opts->extra = TIME_SERIES;
          }
      }
    }

#if DWDEBUG
    fprintf(stderr, "dwiz_set_radio_opt: setting setvar to %d\n", val);
    if (opts->extra != NULL) {
      fprintf(stderr, "dwiz_set_radio_opt: extra now = %d\n", *opts->extra);
    }
#endif

    *opts->setvar = val;
}

static void make_confirmation_text (char *ctxt, DATAINFO *dwinfo, gretlopt *flags)
{
    if (dwinfo->structure == CROSS_SECTION) {
      sprintf(ctxt, _("%s, observations 1 to %d"), _("Cross-sectional data"), 
            datainfo->n);
    } else if (time_series(dwinfo)) {
      int lastobs = dwinfo->t1 + datainfo->n - 1;
      char stobs[OBSLEN];
      char endobs[OBSLEN];
      const char *tslabel;

      tslabel = _(ts_frequency_string(dwinfo->pd));

      if (lastobs > dwinfo->n - 1) {
          dwinfo->n = lastobs + 1;
      }

      ntodate_full(stobs, dwinfo->t1, dwinfo);
      ntodate_full(endobs, lastobs, dwinfo);
      sprintf(ctxt, _("%s, %s to %s"), tslabel, stobs, endobs);
    } else if (dwinfo->structure == PANEL_UNKNOWN) {
      sprintf(ctxt, _("Panel data (%s)\n"
                  "%d cross-sectional units observed over %d periods"),
            _("stacked time series"), dwinfo->n, dwinfo->pd);
    } else if (known_panel(dwinfo)) {
      int nunits = dwinfo->t1;
      int nperiods = datainfo->n / nunits;

      sprintf(ctxt, _("Panel data (%s)\n"
                  "%d cross-sectional units observed over %d periods"),
            (dwinfo->structure == STACKED_TIME_SERIES)? 
            _("stacked time series") : _("stacked cross sections"),
            nunits, nperiods);
    } 

    if (*flags & DW_DROPMISS) {
      strcat(ctxt, "\n");
      strcat(ctxt, _("(dropping missing observations)"));
    }
}

static void make_weekly_stobs (DATAINFO *dwinfo)
{
    int start_days[] = { 6, 7, 1, 2, 3, 4, 5 };

    sprintf(dwinfo->stobs, "1800/01/0%d", start_days[dwinfo->v]);    
}

static int default_start_decade (void)
{
    int d = 1700;

    if (datainfo->S != NULL) {
      d = positive_int_from_string(datainfo->S[0]);
    }
    
    if (d < 0) {
      d = 1700;
    }

    return d;
}

static void compute_default_ts_info (DATAINFO *dwinfo, int newdata)
{
#if DWDEBUG
    char obsstr[OBSLEN];

    fprintf(stderr, "compute_ts_info() called: pd=%d, structure=%d\n",
          dwinfo->pd, dwinfo->structure);
    if (dwinfo->pd == PD_SPECIAL) {
      fprintf(stderr, "breakage: pd = PD_SPECIAL\n");
    }
#endif

    if (dwinfo->pd < 0) {
      dwinfo->pd = 1;
    }
    
    if (dwinfo->structure == CROSS_SECTION) {
      dwinfo->n = 500;
      dwinfo->t1 = 0;
      strcpy(dwinfo->stobs, "1");
    } else if (dwinfo->structure == SPECIAL_TIME_SERIES) {
      dwinfo->n = 500;
      dwinfo->t1 = 0;
      if (dwinfo->pd > 1) {
          int p = dwinfo->pd;

          strcpy(dwinfo->stobs, "1:");
          while ((p = p / 10) > 0) {
            strcat(dwinfo->stobs, "0");
          }
          strcat(dwinfo->stobs, "1");
      } else {
          strcpy(dwinfo->stobs, "1");
      }
    } else if (dwinfo->pd == 1) {
      strcpy(dwinfo->stobs, "1700");
      dwinfo->n = 400;
      dwinfo->t1 = 250;
    } else if (dwinfo->pd == 10) {
      int dd = default_start_decade();

      sprintf(dwinfo->stobs, "%d", dd);
      if (dd > 1700) {
          dwinfo->n = 30;
          dwinfo->t1 = 0;
      } else {
          dwinfo->n = 40;
          dwinfo->t1 = 25;
      }
    } else if (dwinfo->pd == 4) {
      strcpy(dwinfo->stobs, "1700:1");
      dwinfo->n = 1300;
      dwinfo->t1 = 1000;
    } else if (dwinfo->pd == 12) {
      strcpy(dwinfo->stobs, "1700:01");
      dwinfo->n = 3900;
      dwinfo->t1 = 3360;
    } else if (dwinfo->pd == 24) {
      strcpy(dwinfo->stobs, "1:01");
      dwinfo->n = 1500;
      dwinfo->t1 = 0;
    } else if (dwinfo->pd == 52) {
      if (dwinfo->v >= 7) {
          dwinfo->n = 500;
          dwinfo->t1 = 0;
          strcpy(dwinfo->stobs, "1");
      } else {
          make_weekly_stobs(dwinfo);
          dwinfo->n = 13000;
          dwinfo->t1 = 7826;
      }
    } else if (dwinfo->pd == 5 ||
             dwinfo->pd == 6 ||
             dwinfo->pd == 7) {
      strcpy(dwinfo->stobs, "1900/01/01");
      dwinfo->n = 40000;
      if (dwinfo->pd == 5) {
          dwinfo->t1 = 13046;
      } else if (dwinfo->pd == 6) {
          dwinfo->t1 = 15654;
      } else {
          dwinfo->t1 = 18263;
      }
    }

    dwinfo->sd0 = get_date_x(dwinfo->pd, dwinfo->stobs);

    if (newdata) {
      dwinfo->t2 = dwinfo->t1 + 49;
    } else if (datainfo->structure == TIME_SERIES && 
             datainfo->pd == dwinfo->pd) {
      /* make the current start the default */
      dwinfo->t1 = dateton(datainfo->stobs, dwinfo);
    }

    ntodate_full(dwinfo->endobs, dwinfo->n - 1, dwinfo);

#if DWDEBUG
    ntodate_full(obsstr, dwinfo->t1, dwinfo);
    fprintf(stderr, "dwinfo: v=%d, pd=%d, stobs='%s', endobs='%s', sd0=%g, t1=%d (%s)\n",
          dwinfo->v, dwinfo->pd, dwinfo->stobs, dwinfo->endobs, dwinfo->sd0, 
          dwinfo->t1, obsstr);

    ntodate_full(obsstr, datainfo->t1, datainfo);
    fprintf(stderr, "datainfo: pd=%d, stobs='%s', sd0=%g, t1=%d (%s)\n",
          datainfo->pd, datainfo->stobs, datainfo->sd0, datainfo->t1, obsstr);
#endif
}

static int default_panel_size (dw_opts *opts, DATAINFO *dwinfo)
{
    int sz = opts->plf;

    if (dwinfo->pd > 1 && dwinfo->n % dwinfo->pd == 0) {
      if (dwinfo->structure == STACKED_TIME_SERIES) {
          sz = dwinfo->n / dwinfo->pd;
      } else {
          sz = dwinfo->pd;
      }
    } 

    dwinfo->t1 = sz;
    dwinfo->t2 = dwinfo->n / sz;

    return sz;
}

/* translate from the 0-based indexing in the GtkComboBox to
   dataset indexing, for the unit and period variables */

static int translate_panel_vars (dw_opts *opts, int *uv, int *tv)
{
    GList *list = opts->vlist;
    int i, vi;
    int err = 0;

    *uv = *tv = 0;
    
    for (i=0; list != NULL && !err; i++) {
      if (i == opts->uid || i == opts->tid) {
          vi = series_index(datainfo, (const char *) list->data);
          if (vi == datainfo->v) {
            err = E_DATA;
          } else if (i == opts->uid) {
            *uv = vi;
          } else {
            *tv = vi;
          }
      }
      if (*uv > 0 && *tv > 0) {
          break;
      }
      list = list->next;
    }

#if DWDEBUG
    fprintf(stderr, "translate_panel_vars: uid: %d -> %d, tid: %d -> %d\n",
          opts->uid, *uv, opts->tid, *tv);
#endif

    return err;
}

/* Given two user-selected variables that supposedly represent the
   panel unit and period respectively, check that the selection makes
   sense. 
*/

static int process_panel_vars (DATAINFO *dwinfo, dw_opts *opts)
{
    int n = datainfo->n;
    double *uid = NULL;
    double *tid = NULL;
    int uv, tv;
    int nunits = 0;
    int nperiods = 0;
    int err = 0;

    /* FIXME sub-sampled dataset? */

    err = translate_panel_vars(opts, &uv, &tv);
    if (err) {
      return err;
    }

    if (uv == tv) {
      /* "can't happen" */
      errbox(_("The unit and time index variables must be distinct"));
      return E_DATA;
    }

    uid = copyvec(Z[uv], n);
    tid = copyvec(Z[tv], n);

    if (uid == NULL || tid == NULL) {
      nomem();
      err = E_ALLOC;
    }

    if (!err) {
      qsort(uid, n, sizeof *uid, gretl_compare_doubles);
      nunits = count_distinct_values(uid, n);

      qsort(tid, n, sizeof *tid, gretl_compare_doubles);
      nperiods = count_distinct_values(tid, n);

      /* heuristic: if a variable represents either the panel
         unit or period, it must have at least two distinct
         values, and must have fewer values than the total
         number of observations.  Further, the product of
         the number of distinct values for the unit and time
         variables must be at least equal to the number of
         observations, otherwise there will be duplicated
         rows (i.e. more than one row claiming to represent
         unit i, period t, for some i, t).

         Note that the product (nunits * nperiods) may be
         _greater_ than total n: this may mean that we have
         some implicit missing observations.
      */

      if (nunits == 1 || nperiods == 1 || 
          nunits == n || nperiods == n ||
          nunits * nperiods < n) {
          errbox(_("The selected index variables do not represent "
                 "a panel structure"));
          err = E_DATA;
      } else {
          dwinfo->n = nunits; 
          dwinfo->pd = nperiods;
      }
    }

    free(uid);
    free(tid);

    return err;
}

/* Try to assemble a list of at least two potential panel index
   variables.  These variables must have nothing but non-negative
   integer values, and they must have at least two distinct values
   (i.e. cannot be constants).
*/

static int panelvars_list_ok (dw_opts *opts)
{
    GList *vlist = NULL;
    int i, t, ok;
    double xt;
    int err = 0;

    if (opts->flags & DW_VLIST_DONE) {
      return (opts->vlist != NULL);
    }

    for (i=1; i<datainfo->v; i++) {
      ok = 1;
      for (t=datainfo->t1; t<=datainfo->t2; t++) {
          xt = Z[i][t];
          if (na(xt) || xt < 0 || xt != floor(xt)) {
            ok = 0;
            break;
          }
      }
      if (ok) {
          ok = !gretl_isconst(datainfo->t1, datainfo->t2, Z[i]);
      }
      if (ok) {
          vlist = g_list_append(vlist, datainfo->varname[i]); 
      }
    }

    if (vlist == NULL) {
      err = 1;
    } else if (g_list_length(vlist) < 2) {
      g_list_free(vlist);
      vlist = NULL;
      err = 1;
    }

    opts->vlist = vlist;
    opts->flags |= DW_VLIST_DONE;

#if DWDEBUG
    fprintf(stderr, "panelvars_list_ok: returning %d\n", !err);
#endif

    return !err;
}

/* Check whether or not it's feasible to offer a panel interpretation
   of the current dataset.  This is impossible if the total number of
   observations is prime (cannot be factored as n * T) and the dataset
   contains no variables that might plausibly represent panel unit and
   period respectively.
*/

static int panel_possible (dw_opts *opts)
{
    int ok = 1;

    if (opts->flags & DW_NO_PANEL) {
      return 0;
    }

    eval_n_is_prime(opts);

    if (opts->flags & DW_N_PRIME) {
      /* are there feasible index vars? */
      ok = panelvars_list_ok(opts);
    } 

    if (!ok) {
      opts->flags |= DW_NO_PANEL;
      warnbox(_("This dataset cannot be interpreted as a panel"));
    }

    return ok;
}

/* callback from combo: update the panel unit or time variable,
   building in a guard against selecting the same variable in
   both roles
*/

static gboolean update_panel_var (GtkWidget *box, dw_opts *opts)
{
    gint v = gtk_combo_box_get_active(GTK_COMBO_BOX(box));
    int i = GPOINTER_TO_INT(g_object_get_data(G_OBJECT(box), "index"));
    GtkWidget *other = g_object_get_data(G_OBJECT(box), "other");

    if (i == 0) {
      opts->uid = v;
    } else {
      opts->tid = v;
    }

    if (other != NULL) {
      gint v2 = gtk_combo_box_get_active(GTK_COMBO_BOX(other));

      if (v == v2) {
          /* we have a conflict: fix it */
          if (v > 0) {
            gtk_combo_box_set_active(GTK_COMBO_BOX(other), 0);
          } else {
            gtk_combo_box_set_active(GTK_COMBO_BOX(other), 1);
          }
      }
    }

#if DWDEBUG
    fprintf(stderr, "update_panel_var: i=%d, uid = %d, tid = %d\n",
          i, opts->uid, opts->tid);
#endif

    return FALSE;
}

/* Try to find the most likely candidates for the unit (uid) and time
   (tid) index variables, given a list of variables that might
   perhaps be acceptable.
*/

static void panelvar_candidates (GList *vlist, int *uid, int *tid)
{
    GList *list = vlist;
    const char *vname;
    char vtest[VNAMELEN];
    int i;

    *uid = *tid = -1;

    for (i=0; list != NULL; i++) {
      vname = (const char *) list->data;
      strcpy(vtest, vname);
      lower(vtest);
      if (*tid < 0) {
          if (!strcmp(vtest, "time") || 
            !strcmp(vtest, "year") ||
            !strcmp(vtest, "period")) {
            *tid = i;
          }
      }
      if (*uid < 0) {
          if (!strcmp(vtest, "unit") ||
            !strcmp(vtest, "group") ||
            !strcmp(vtest, "country") ||
            !strcmp(vtest, "id")) {
            *uid = i;
          }
      }
      if (*uid >= 0 && *tid >= 0) {
          break;
      }
      list = list->next;
    }

    /* if we didn't succeed above, just ensure a non-conflicting
       assignment to uidx and tidx */

    if (*uid < 0) {
      if (*tid < 0) {
          *uid = 0;
          *tid = 1;
      } else {
          *uid = (*tid == 0)? 1 : 0;
      }
    } else if (*tid < 0) {
      *tid = (*uid == 0)? 1 : 0;
    }
}

/* combo box selector for variables possibly representing the
   panel unit and time-period */

static GtkWidget *dwiz_combo (GList *vlist, dw_opts *opts)
{
    const char *strs[] = {
      N_("Unit or group index variable"),
      N_("Time index variable")
    };
    GtkWidget *w;
    GtkWidget *table;
    GtkWidget *combo[2];
    int i;

    panelvar_candidates(vlist, &opts->uid, &opts->tid);

#if DWDEBUG
    fprintf(stderr, "dwiz_combo: uid = %d, tid = %d\n",
          opts->uid, opts->tid);
#endif

    table = gtk_table_new(2, 2, FALSE);
    gtk_table_set_col_spacings(GTK_TABLE(table), 5);
    gtk_table_set_row_spacings(GTK_TABLE(table), 5);

    for (i=0; i<2; i++) {
      GList *list = vlist;

      w = gtk_label_new(_(strs[i]));
      gtk_misc_set_alignment(GTK_MISC(w), 1.0, 0.5);
      gtk_table_attach_defaults(GTK_TABLE(table), w, 0, 1, i, i+1);

      combo[i] = gtk_combo_box_new_text();
      gtk_table_attach_defaults(GTK_TABLE(table), combo[i], 1, 2, i, i+1);

      while (list != NULL) {
          gtk_combo_box_append_text(GTK_COMBO_BOX(combo[i]), list->data);
          list = list->next;
      }

      gtk_combo_box_set_active(GTK_COMBO_BOX(combo[i]), (i == 0)? opts->uid : opts->tid);
      g_object_set_data(G_OBJECT(combo[i]), "index", GINT_TO_POINTER(i));
      g_signal_connect(G_OBJECT(combo[i]), "changed",
                   G_CALLBACK(update_panel_var), opts);
    }

    /* cross-connect the selectors */
    g_object_set_data(G_OBJECT(combo[0]), "other", combo[1]);
    g_object_set_data(G_OBJECT(combo[1]), "other", combo[0]);

    return table;
}

static void dw_set_custom_frequency (GtkWidget *w, DATAINFO *dwinfo)
{
    dwinfo->pd = (int) GTK_ADJUSTMENT(w)->value;
#if DWDEBUG
    fprintf(stderr, "dw_set_custom_frequency: set dwinfo->pd = %d\n", dwinfo->pd);
#endif
}

static void dw_set_t1 (GtkWidget *w, DATAINFO *dwinfo)
{
    dwinfo->t1 = (int) GTK_ADJUSTMENT(w)->value;
#if DWDEBUG
    fprintf(stderr, "dw_set_t1: set dwinfo->t1 = %d\n", dwinfo->t1);
#endif
}

/* spinner for either time-series starting observation or
   custom time-series frequency */

static GtkWidget *dwiz_spinner (GtkWidget *hbox, DATAINFO *dwinfo, int step)
{
    GtkObject *adj;
    GtkWidget *spin;
    int spinmin, spinmax, spinstart;

    if (step == DW_STARTING_OBS) {
      GtkWidget *label = gtk_label_new(_(ts_frequency_string(dwinfo->pd)));

      gtk_widget_show(label);
      gtk_box_pack_start(GTK_BOX(hbox), label, FALSE, FALSE, 5);

      compute_default_ts_info(dwinfo, 0);
      spinmin = 0;
      spinmax = dwinfo->n - 1;
      spinstart = dwinfo->t1;
    } else {
      /* custom time-series frequency */
      spinmin = 1;
      spinmax = 100; /* arbitrary */
      spinstart = dwinfo->pd;
    } 

    /* appropriate step size? */
    adj = gtk_adjustment_new(spinstart, spinmin, spinmax,
                       1, 10, 0);

    if (step == DW_STARTING_OBS) {
      g_signal_connect(G_OBJECT(adj), "value-changed", 
                   G_CALLBACK(dw_set_t1), dwinfo);
      spin = obs_button_new(GTK_ADJUSTMENT(adj), dwinfo);
    } else {      
      g_signal_connect(G_OBJECT(adj), "value-changed", 
                   G_CALLBACK(dw_set_custom_frequency), dwinfo);
      spin = gtk_spin_button_new(GTK_ADJUSTMENT(adj), 1, 0);
    } 

    gtk_entry_set_activates_default(GTK_ENTRY(spin), TRUE);
    gtk_box_pack_start(GTK_BOX(hbox), spin, FALSE, FALSE, 0);
    gtk_widget_show(spin);

    return spin;
}

static void dwiz_startobs_spinner (DATAINFO *dwinfo,
                           GtkWidget *vbox)
{
    GtkWidget *hbox = gtk_hbox_new(FALSE, 5);

    dwiz_spinner(hbox, dwinfo, DW_STARTING_OBS);
    gtk_box_pack_start(GTK_BOX(vbox), hbox, FALSE, FALSE, 5);
    gtk_widget_show(hbox);
}

/* Panel: callback for setting the number of cross-sectional units, n,
   and the number of time periods, T, via spin buttons.  We allow the
   user to vary either n or T, subject to the constraint that n * T
   equals the total number of observations.
*/

static void dw_set_panel_dims (GtkSpinButton *w, DATAINFO *dwinfo)
{
    int idx = GPOINTER_TO_INT(g_object_get_data(G_OBJECT(w), "idx"));
    int plf = GPOINTER_TO_INT(g_object_get_data(G_OBJECT(w), "plf"));
    GtkSpinButton *nspin = NULL, *Tspin = NULL;
    int oldn = dwinfo->t1;
    int oldT = dwinfo->t2;
    int n = 0, T = 0; 

    if (idx == 0) {
      nspin = w;
      Tspin = g_object_get_data(G_OBJECT(w), "Tspin");
    } else {
      Tspin = w;
      nspin = g_object_get_data(G_OBJECT(w), "nspin");
    }

    if (nspin != NULL) {
      n = gtk_spin_button_get_value_as_int(nspin);
    }

    if (Tspin != NULL) {
      T = gtk_spin_button_get_value_as_int(Tspin);
    }

    if (nspin != NULL && Tspin != NULL) {
      int nTmax = datainfo->n / plf;

      if (n != oldn) {
          if (n > oldn) {
            while (datainfo->n % n && n <= nTmax) {
                n++;
            }
          } else if (n < oldn) {
            while (datainfo->n % n && n >= plf) {
                n--;
            }
          }
          if (datainfo->n % n) {
            n = oldn;
          }
          T = datainfo->n / n;
      } else if (T != oldT) {
          if (T > oldT) {
            while (datainfo->n % T && T <= nTmax) {
                T++;
            }
          } else if (T < oldT) {
            while (datainfo->n % T && T >= plf) {
                T--;
            }
          }
          if (datainfo->n % T) {
            T = oldT;
          }     
          n = datainfo->n / T;
      }

      gtk_spin_button_set_value(nspin, (double) n);
      gtk_spin_button_set_value(Tspin, (double) T);
    }

    dwinfo->t1 = n;
    dwinfo->t2 = T;

#if DWDEBUG
    fprintf(stderr, "dw_set_panel_dims: n: %d -> %d, T: %d -> %d\n", 
          oldn, n, oldT, T);
#endif
}

static void dwiz_make_panel_spinners (dw_opts *opts,
                              DATAINFO *dwinfo,
                              GtkWidget *vbox)
{
    const char *labels[] = {
      N_("Number of cross-sectional units"),
      N_("Number of time periods")
    };
    GtkWidget *label;
    GtkWidget *table;
    GtkObject *adj;
    GtkWidget *pspin[2];
    int spinmin, spinmax, spinstart;
    int i;

    spinmin = opts->plf;
    spinmax = datainfo->n / opts->plf;
    spinstart = default_panel_size(opts, dwinfo);

    table = gtk_table_new(2, 2, FALSE);
    gtk_table_set_col_spacings(GTK_TABLE(table), 5);
    gtk_table_set_row_spacings(GTK_TABLE(table), 5);

    for (i=0; i<2; i++) {
      label = gtk_label_new(_(labels[i]));
      gtk_misc_set_alignment(GTK_MISC(label), 1.0, 0.5);
      gtk_table_attach_defaults(GTK_TABLE(table), label, 0, 1, i, i+1);

      if (i == 1) {
          spinstart = datainfo->n / spinstart;
      }

      adj = gtk_adjustment_new(spinstart, spinmin, spinmax, 1, 10, 0);
      pspin[i] = gtk_spin_button_new(GTK_ADJUSTMENT(adj), 1, 0);
      g_object_set_data(G_OBJECT(pspin[i]), "idx", GINT_TO_POINTER(i));
      g_object_set_data(G_OBJECT(pspin[i]), "plf", GINT_TO_POINTER(opts->plf));
      g_signal_connect(G_OBJECT(pspin[i]), "value-changed", 
                   G_CALLBACK(dw_set_panel_dims), dwinfo);
      gtk_entry_set_activates_default(GTK_ENTRY(pspin[i]), TRUE);
      gtk_table_attach_defaults(GTK_TABLE(table), pspin[i], 1, 2, i, i+1);
    }

    g_object_set_data(G_OBJECT(pspin[0]), "Tspin", pspin[1]);
    g_object_set_data(G_OBJECT(pspin[1]), "nspin", pspin[0]);

    gtk_widget_show_all(table);
    gtk_box_pack_start(GTK_BOX(vbox), table, FALSE, FALSE, 5);
}

static void maybe_add_missobs_purger (GtkWidget *vbox, gretlopt *flags)
{
    double missfrac = 0.0;
    int active = 0;

    if (*flags & DW_DROPMISS) {
      active = 1;
    } else {
      missfrac = missing_obs_fraction((const double **) Z, 
                              datainfo);
    }

    if (active || (missfrac > 0 && missfrac < 0.12)) {
      GtkWidget *hbox = gtk_hbox_new(FALSE, 5);
      GtkWidget *chk;

      chk = gretl_option_check_button(_("purge missing observations"),
                              flags, DW_DROPMISS);
      gtk_box_pack_start(GTK_BOX(hbox), chk, FALSE, FALSE, 5);
      gtk_box_pack_start(GTK_BOX(vbox), hbox, FALSE, FALSE, 5);
      if (active) {
          gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(chk), TRUE);
      }
      gtk_widget_show_all(hbox);
    }
}

/* Calculate the options set-up for a given step of the wizard
   process: How many radio-button options should we show (if any)?
   What variable are we setting?  What should be the default value for
   this variable?
*/

static void set_up_dw_opts (dw_opts *opts, int step,
                      DATAINFO *dwinfo)
{
    opts->setvar = NULL;
    opts->extra = NULL;
    opts->spinner = NULL;
    opts->n_radios = 0;

    opts->deflt = dwiz_radio_default(dwinfo, step);

    if (step == DW_SET_TYPE) {
      if (opts->flags & DW_NO_PANEL) {
          opts->n_radios = 2;
      } else {
          opts->n_radios = 3;
      }
      opts->setvar = &dwinfo->structure;
    } else if (step == DW_TS_FREQUENCY) {
      opts->n_radios = TS_INFO_MAX;
      opts->setvar = &dwinfo->pd;
      opts->extra = &dwinfo->structure;
    } else if (step == DW_WEEKLY_SELECT) {
      opts->n_radios = 8;
      opts->setvar = &dwinfo->v;
    } else if (step == DW_PANEL_MODE) {
      opts->n_radios = PANEL_INFO_MAX;
      opts->setvar = &dwinfo->structure;
      eval_n_is_prime(opts);
    } else if (step == DW_PANEL_SIZE) {
      opts->setvar = &dwinfo->pd;
    } 
}

/* make two or more radio buttons based on the current setings in
   the "opts" structure
 */

static void dwiz_build_radios (int step, DATAINFO *dwinfo, 
                         dw_opts *opts, 
                         GtkWidget *vbox)
{
    GSList *group = NULL;
    GtkWidget *button = NULL;
    int i, setval;

    for (i=0; i<opts->n_radios; i++) {
      GtkWidget *hbox;

      /* determine the value to be set by button i */
      setval = dwiz_i_to_setval(dwinfo, step, i);

#if DWDEBUG > 1
      fprintf(stderr, "opts[%d]: setval = %d (deflt=%d)\n", i, 
            setval, opts->deflt);
#endif

      hbox = gtk_hbox_new(FALSE, 5);
      gtk_box_pack_start(GTK_BOX(vbox), hbox, FALSE, FALSE, 0);
      gtk_widget_show(hbox);

      if (button != NULL) {
          group = gtk_radio_button_get_group(GTK_RADIO_BUTTON(button));
      } else {
          group = NULL;
      }

      button = gtk_radio_button_new_with_label(group, 
                                     _(dwiz_radio_strings(step, i)));
      gtk_box_pack_start(GTK_BOX(hbox), button, FALSE, FALSE, 5);

      if (step == DW_TS_FREQUENCY && i == opts->n_radios - 1) {
          /* time series, "other" (custom) frequency: need spinner */
          GtkWidget *freqspin = dwiz_spinner(hbox, dwinfo, step);

          gtk_widget_set_sensitive(freqspin, FALSE);
          opts->spinner = freqspin;
      } 

      g_signal_connect(G_OBJECT(button), "clicked",
                   G_CALLBACK(dwiz_set_radio_opt), opts);
      g_object_set_data(G_OBJECT(button), "action", GINT_TO_POINTER(setval));

      if (step == DW_PANEL_MODE && dw_n_is_prime(opts)) {
          /* only the "index variables" option should be active */
          gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(button), 
                               setval == PANEL_UNKNOWN);
          gtk_widget_set_sensitive(button, setval == PANEL_UNKNOWN);
      } else if (opts->deflt == setval) {
#if DWDEBUG > 1
          fprintf(stderr, "opts[%d]: setval = deflt = %d\n", i, setval);
#endif
          gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(button), TRUE);
          if (opts->setvar != NULL && setval >= 0) {
            /* pre-set the variable to its default value */
            *opts->setvar = setval;
#if DWDEBUG > 1
            fprintf(stderr, "button: setting setvar to %d\n", setval);
#endif
          }
      }

      if (step == DW_PANEL_MODE && i == opts->n_radios - 1) {
          if (!panelvars_list_ok(opts)) {
            /* disable the "index variables" option */
            gtk_widget_set_sensitive(button, FALSE);
            gretl_tooltips_add(button, 
                           _("The data set contains no suitable index variables"));
          }
      }

      gtk_widget_show(button);
    }
}

static void dwiz_panelvars_selector (dw_opts *opts,
                             DATAINFO *dwinfo,
                             GtkWidget *vbox)
{
    GtkWidget *hbox = gtk_hbox_new(FALSE, 5);
    GtkWidget *table = dwiz_combo(opts->vlist, opts);

    gtk_box_pack_start(GTK_BOX(hbox), table, FALSE, FALSE, 5);
    gtk_box_pack_start(GTK_BOX(vbox), hbox, FALSE, FALSE, 5);
    gtk_widget_show_all(hbox);
}

/* Where should we be going, when the Forward or Back button
   is clicked? */

static int dwiz_compute_step (int prevstep, int direction, DATAINFO *dwinfo, 
                        dw_opts *opts)
{
    int create = opts->flags & DW_CREATE;
    int step = 0;

#if DWDEBUG
    fprintf(stderr, "dwiz_compute_step: incoming step = %d\n", prevstep);
#endif

    if (direction == DW_FORWARD) {
      if (prevstep == DW_SET_TYPE) {
          if (time_series(dwinfo)) {
            step = DW_TS_FREQUENCY;
          } else if (known_panel(dwinfo)) {
            if (create) {
                dwinfo->structure = STACKED_TIME_SERIES;
                step = DW_PANEL_SIZE;
            } else {
                step = DW_PANEL_MODE;
            }
          } else if (dwinfo->structure == PANEL_UNKNOWN) {
            step = DW_PANEL_MODE;
          } else {
            /* cross section */
            dwinfo->pd = 1;
            step = DW_CONFIRM;
          }       
      } else if (prevstep == DW_TS_FREQUENCY) {
          if (dwinfo->structure != SPECIAL_TIME_SERIES) {
            if (dwinfo->pd == 52) {
                step = DW_WEEKLY_SELECT;
            } else {
                step = DW_STARTING_OBS;
            }
          } else {
            step = DW_STARTING_OBS;
          }
      } else if (prevstep == DW_WEEKLY_SELECT) {
          step = DW_STARTING_OBS;
      } else if (prevstep == DW_PANEL_MODE) {
          if (dwinfo->structure == PANEL_UNKNOWN) {
            step = DW_PANEL_VARS;
          } else {
            step = DW_PANEL_SIZE;
          }
      } else if (prevstep == DW_PANEL_VARS) {
          if (process_panel_vars(dwinfo, opts)) {
            /* error: don't proceed */
            step = DW_PANEL_VARS;
          } else {
            step = DW_CONFIRM;
          }
      } else if (prevstep == DW_STARTING_OBS || 
               prevstep == DW_PANEL_SIZE) {
          step = DW_CONFIRM;
      } 
    } else if (direction == DW_BACK) {
      if (prevstep == DW_TS_FREQUENCY || prevstep == DW_PANEL_MODE) {
          step = DW_SET_TYPE;
      } else if (prevstep == DW_STARTING_OBS) {
          if (dwinfo->pd == 52) {
            step = DW_WEEKLY_SELECT;
          } else {
            step = DW_TS_FREQUENCY;
          }
      } else if (prevstep == DW_WEEKLY_SELECT) {
          step = DW_TS_FREQUENCY;
      } else if (prevstep == DW_PANEL_SIZE) {
          step = (create)? DW_SET_TYPE : DW_PANEL_MODE;
      } else if (prevstep == DW_PANEL_VARS) {
          step = DW_PANEL_MODE;
      } else if (prevstep == DW_CONFIRM) {
          if (dwinfo->structure == TIME_SERIES || 
            dwinfo->structure == SPECIAL_TIME_SERIES) {
            step = DW_STARTING_OBS;
          } else if (dwinfo->structure == STACKED_TIME_SERIES ||
                   dwinfo->structure == STACKED_CROSS_SECTION) {
            step = DW_PANEL_SIZE;
          } else {
            step = DW_SET_TYPE;
          }
      } 
    }

#if DWDEBUG
    fprintf(stderr, "dwiz_compute_step: returning step = %d\n", step);
#endif

    return step;
}

/* clear a given notebook page, but leave the title string
   unchanged */

static void kill_dwiz_child (GtkWidget *w)
{
    int t = GPOINTER_TO_INT(g_object_get_data(G_OBJECT(w), "title"));

    if (!t) {
      gtk_widget_destroy(w);
    } 
}

static void clear_dwiz_page (GtkWidget *page)
{
    gtk_container_foreach(GTK_CONTAINER(page),
                    (GtkCallback) kill_dwiz_child,
                    NULL);
}

/* select the appropriate buttons to show, depending on the
   step */

static void dwiz_button_visibility (GtkWidget *dlg, int step)
{
    GtkWidget *cancel  = g_object_get_data(G_OBJECT(dlg), "cancel");
    GtkWidget *back    = g_object_get_data(G_OBJECT(dlg), "back");
    GtkWidget *forward = g_object_get_data(G_OBJECT(dlg), "forward");
    GtkWidget *apply   = g_object_get_data(G_OBJECT(dlg), "apply");
    GtkWidget *help    = g_object_get_data(G_OBJECT(dlg), "help");

    if (step == DW_SET_TYPE) {
      gtk_widget_show(cancel);
      gtk_widget_hide(back);
      gtk_widget_show(forward);
      gtk_widget_hide(apply);
    } else if (step == DW_CONFIRM) {
      gtk_widget_show(cancel);
      gtk_widget_show(back);
      gtk_widget_hide(forward);
      gtk_widget_show(apply);
    } else {
      gtk_widget_show(cancel);
      gtk_widget_show(back);
      gtk_widget_show(forward);
      gtk_widget_hide(apply);
    }

    if (step == DW_PANEL_MODE) {
      gtk_widget_show(help);
    } else {
      gtk_widget_hide(help);
    }
}

static void add_editing_option (GtkWidget *vbox, gretlopt *flags)
{
    GtkWidget *hbox, *b;

    hbox = gtk_hbox_new(FALSE, 5);
    b = gretl_option_check_button(_("start entering data values"),
                          flags, DW_SSHEET);
    gtk_box_pack_start(GTK_BOX(hbox), b, FALSE, FALSE, 5);
    gtk_box_pack_start(GTK_BOX(vbox), hbox, FALSE, FALSE, 5);    
}

/* build the appropriate notebook page for the given step */

static void dwiz_prepare_page (GtkNotebook *nb,
                         gint step,
                         DATAINFO *dwinfo)
{
    GtkWidget *page = gtk_notebook_get_nth_page(nb, step);
    GtkWidget *dlg = g_object_get_data(G_OBJECT(nb), "dlg");
    dw_opts *opts = g_object_get_data(G_OBJECT(dlg), "opts");

#if DWDEBUG    
    fprintf(stderr, "Got Prepare, step = %d\n", step);
#endif

    if (step == DW_CONFIRM) {
      /* the final page */
      GtkWidget *w = g_object_get_data(G_OBJECT(page), "label");
      char ctxt[512];

      make_confirmation_text(ctxt, dwinfo, &opts->flags);
      gtk_label_set_text(GTK_LABEL(w), ctxt);
      if ((opts->flags & DW_CREATE) && datainfo->n < 1001) {
          add_editing_option(page, &opts->flags);
      }
    } else {
      /* all other pages */
      set_up_dw_opts(opts, step, dwinfo);
      clear_dwiz_page(page);

      if (opts->n_radios > 0) {
          dwiz_build_radios(step, dwinfo, opts, page);
      }

      if (step == DW_STARTING_OBS) {
          dwiz_startobs_spinner(dwinfo, page);
          if (Z != NULL && dataset_is_daily(dwinfo)) {
            maybe_add_missobs_purger(page, &opts->flags);
          }
      } else if (step == DW_PANEL_SIZE) {
          dwiz_make_panel_spinners(opts, dwinfo, page);
      } else if (step == DW_PANEL_VARS) {
          dwiz_panelvars_selector(opts, dwinfo, page);
      }
    }

    gtk_widget_show_all(page);
    dwiz_button_visibility(dlg, step);
}

static void dwiz_finalize (GtkWidget *dlg, DATAINFO *dwinfo,
                     int cancel)
{
    dw_opts *opts = g_object_get_data(G_OBJECT(dlg), "opts");

    if (!cancel) {
      dwiz_make_changes(dwinfo, opts, dlg);
    } else if (opts->flags & DW_CREATE) {
      /* aborting creation of new dataset */
      gui_clear_dataset();
    }

    gtk_widget_destroy(dlg);
}

/* callback for the Cancel button */

static void dwiz_cancel (GtkWidget *b, DATAINFO *dwinfo)
{
    GtkWidget *dlg = g_object_get_data(G_OBJECT(b), "dlg");

    dwiz_finalize(dlg, dwinfo, 1);
}

/* callback for the Apply button */

static void dwiz_apply (GtkWidget *b, DATAINFO *dwinfo)
{
    GtkWidget *dlg = g_object_get_data(G_OBJECT(b), "dlg");

    dwiz_finalize(dlg, dwinfo, 0);
}

/* callback for the Back button */

static void dwiz_back (GtkWidget *b, GtkWidget *dlg)
{
    GtkNotebook *nb = g_object_get_data(G_OBJECT(dlg), "nb");
    int pg = gtk_notebook_get_current_page(nb);
    DATAINFO *dwinfo = g_object_get_data(G_OBJECT(dlg), "dwinfo");
    dw_opts *opts = g_object_get_data(G_OBJECT(dlg), "opts");

    pg = dwiz_compute_step(pg, DW_BACK, dwinfo, opts);
    dwiz_prepare_page(nb, pg, dwinfo);
    gtk_notebook_set_current_page(nb, pg);
}

/* callback for the Forward button */

static void dwiz_forward (GtkWidget *b, GtkWidget *dlg)
{
    GtkNotebook *nb = g_object_get_data(G_OBJECT(dlg), "nb");
    int pg = gtk_notebook_get_current_page(nb);
    DATAINFO *dwinfo = g_object_get_data(G_OBJECT(dlg), "dwinfo");
    dw_opts *opts = g_object_get_data(G_OBJECT(dlg), "opts");
    int newpg;

    if (pg == DW_SET_TYPE && any_panel(dwinfo) && !panel_possible(opts)) {
      /* special case: called for panel but it won't work */
      dwinfo->structure = datainfo->structure;
      dwiz_prepare_page(nb, DW_SET_TYPE, dwinfo);
      gtk_notebook_set_current_page(nb, DW_SET_TYPE);
      return;
    }

    newpg = dwiz_compute_step(pg, DW_FORWARD, dwinfo, opts);
    if (newpg != pg) {
      dwiz_prepare_page(nb, newpg, dwinfo);
      gtk_notebook_set_current_page(nb, newpg);
    }
}

/* initial setup for the final conformation text */

static void dwiz_confirm_label (GtkWidget *page)
{
    GtkWidget *hbox = gtk_hbox_new(FALSE, 5);
    GtkWidget *label = gtk_label_new("");

    gtk_box_pack_start(GTK_BOX(hbox), label, FALSE, FALSE, 5);
    gtk_box_pack_start(GTK_BOX(page), hbox, FALSE, FALSE, 5);
    g_object_set_data(G_OBJECT(page), "label", label);
}

static void free_dwinfo (GtkWidget *w, DATAINFO *dwinfo)
{
    free(dwinfo);
}

static void free_dw_opts (GtkWidget *w, dw_opts *opts)
{
    if (opts->vlist != NULL) {
      g_list_free(opts->vlist);
    }
    free(opts);
}

/* Create all the buttons that we'll need.  Which of these will
   actually be shown depends on the step */

static void build_dwiz_buttons (GtkWidget *dlg, DATAINFO *dwinfo)
{
    GtkWidget *hbox = GTK_DIALOG(dlg)->action_area;
    GtkWidget *b;

    /* "Cancel" button */
    b = gtk_button_new_from_stock(GTK_STOCK_CANCEL);
    g_object_set_data(G_OBJECT(b), "dlg", dlg);
    g_signal_connect(G_OBJECT(b), "clicked", 
                 G_CALLBACK(dwiz_cancel),
                 dwinfo);
    gtk_container_add(GTK_CONTAINER(hbox), b);
    g_object_set_data(G_OBJECT(dlg), "cancel", b);

    /* "Back" button */
    b = gtk_button_new_from_stock(GTK_STOCK_GO_BACK);
    g_object_set_data(G_OBJECT(b), "dlg", dlg);
    g_signal_connect(G_OBJECT(b), "clicked", 
                 G_CALLBACK(dwiz_back),
                 dlg);
    gtk_container_add(GTK_CONTAINER(hbox), b);
    g_object_set_data(G_OBJECT(dlg), "back", b);

    /* "Forward" button */
    b = gtk_button_new_from_stock(GTK_STOCK_GO_FORWARD);
    g_object_set_data(G_OBJECT(b), "dlg", dlg);
    g_signal_connect(G_OBJECT(b), "clicked", 
                 G_CALLBACK(dwiz_forward),
                 dlg);
    gtk_container_add(GTK_CONTAINER(hbox), b);
    g_object_set_data(G_OBJECT(dlg), "forward", b);

    /* "Apply" button */
    b = gtk_button_new_from_stock(GTK_STOCK_APPLY);
    g_object_set_data(G_OBJECT(b), "dlg", dlg);
    g_signal_connect(G_OBJECT(b), "clicked", 
                 G_CALLBACK(dwiz_apply),
                 dwinfo);
    gtk_container_add(GTK_CONTAINER(hbox), b);
    g_object_set_data(G_OBJECT(dlg), "apply", b);

    /* Help button for panel mode selection */
    b = context_help_button(hbox, PANEL_MODE);
    g_object_set_data(G_OBJECT(dlg), "help", b);
}

/* the title for the top of a given notebook page */

static void dwiz_page_add_title (GtkWidget *vbox, int i, int smax)
{
    GtkWidget *hbox = gtk_hbox_new(FALSE, 5);
    GtkWidget *label= gtk_label_new(NULL);
    gchar *buf;

    buf = g_markup_printf_escaped("<span face=\"sans\" "
                          "weight=\"bold\" "
                          "color=\"white\" "
                          "background=\"#6C7B8A\" "
                          "size=\"xx-large\"> %-*s </span>", 
                          smax, _(wizcode_string(i)));
    gtk_label_set_markup(GTK_LABEL(label), buf);
    g_free(buf);
    g_object_set_data(G_OBJECT(hbox), "title", GINT_TO_POINTER(1));
    gtk_box_pack_start(GTK_BOX(hbox), label, FALSE, FALSE, 5);
    gtk_box_pack_start(GTK_BOX(vbox), hbox, FALSE, FALSE, 5);
}

static dw_opts *dw_opts_new (int create)
{
    dw_opts *opts = mymalloc(sizeof *opts);

    if (opts != NULL) {
      opts->flags = (create)? DW_CREATE : 0;
      opts->vlist = NULL;
      opts->uid = opts->tid = 0;

      if (create) {
          eval_n_is_prime(opts);
      }
    }

    return opts;
}

/* The main driver for the "wizard".  If "create" is non-zero that
   means we're setting the structure for a newly created dataset,
   otherwise we're modifying the structure of an existing dataset.
*/

static void data_structure_wizard (int create)
{
    GtkWidget *dialog; 
    GtkWidget *vbox; 
    GtkWidget *nb;
    GtkWidget *page;
    DATAINFO *dwinfo;
    dw_opts *opts;
    int i, n, smax = 0;

    dwinfo = datainfo_new();
    if (dwinfo == NULL) {
      nomem();
      return;
    }

    opts = dw_opts_new(create);
    if (opts == NULL) {
      free(dwinfo);
      return;
    }

    /* copy current relevant info */
    dwinfo_init(dwinfo);

    /* GTK dialog wrapper */
    dialog = gretl_dialog_new(_("Data structure wizard"), mdata->main,
                        GRETL_DLG_QUASI_MODAL);
    g_object_set_data(G_OBJECT(dialog), "dwinfo", dwinfo);
    g_object_set_data(G_OBJECT(dialog), "opts", opts);
    vbox = GTK_DIALOG(dialog)->vbox;

    /* notebook to hold the steps */
    nb = gtk_notebook_new();
    g_object_set_data(G_OBJECT(nb), "dlg", dialog);
    gtk_notebook_set_show_tabs(GTK_NOTEBOOK(nb), FALSE);
    gtk_notebook_set_show_border(GTK_NOTEBOOK(nb), FALSE);
    gtk_container_add(GTK_CONTAINER(vbox), nb);

    g_object_set_data(G_OBJECT(dialog), "nb", nb);

    g_signal_connect(G_OBJECT(dialog), "destroy", 
                 G_CALLBACK(free_dwinfo), 
                 dwinfo);
    g_signal_connect(G_OBJECT(dialog), "destroy", 
                 G_CALLBACK(free_dw_opts), 
                 opts);

    for (i=0; i<=DW_CONFIRM; i++) {
      n = g_utf8_strlen(_(wizcode_string(i)), -1);
      if (n > smax) {
          smax = n;
      }
    }

    /* make all the notebook pages */
    for (i=0; i<=DW_CONFIRM; i++) {
      page = gtk_vbox_new(FALSE, 5);
      gtk_container_set_border_width(GTK_CONTAINER(page), 5);
      dwiz_page_add_title(page, i, smax);
      gtk_notebook_append_page(GTK_NOTEBOOK(nb), page, NULL);
      if (i == DW_CONFIRM) {
          dwiz_confirm_label(page);
      }
      gtk_widget_show(page);
    }

    build_dwiz_buttons(dialog, dwinfo);
    gtk_widget_show(nb);

    dwiz_prepare_page(GTK_NOTEBOOK(nb), 0, dwinfo);
    gtk_notebook_set_current_page(GTK_NOTEBOOK(nb), 0);

    gtk_widget_show(dialog);
}

/* public interface */

/* Take the user through a series of dialogs to define the structure
   of the data set, either when creating a new data set or by way of
   restructuring an existing data set.
*/

void data_structure_dialog (void)
{
    data_structure_wizard(0);
}

void new_data_structure_dialog (void)
{
    data_structure_wizard(1);    
}

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