mode: New order statistic.

[pspp] / src / math / mode.c

diff --git a/src/math/mode.c b/src/math/mode.c
new file mode 100644 (file)
index 0000000..6c9f0c4
--- /dev/null
+++ b/src/math/mode.c
@@ -0,0 +1,66 @@
+/* PSPP - a program for statistical analysis.
+   Copyright (C) 2008, 2009, 2011, 2022 Free Software Foundation, Inc.
+
+   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 <config.h>
+
+#include "math/mode.h"
+
+#include "data/casereader.h"
+#include "data/val-type.h"
+#include "data/variable.h"
+#include "libpspp/assertion.h"
+#include "libpspp/cast.h"
+
+#include "gl/xalloc.h"
+
+
+static void
+mode_destroy (struct statistic *stat)
+{
+  struct mode *mode = UP_CAST (stat, struct mode, parent.parent);
+  free (mode);
+}
+
+static void
+mode_accumulate (struct statistic *stat, const struct ccase *cx UNUSED,
+                 double c, double cc UNUSED, double y)
+{
+  struct mode *mode = UP_CAST (stat, struct mode, parent.parent);
+  if (c > mode->mode_weight)
+    {
+      mode->mode = y;
+      mode->mode_weight = c;
+      mode->n_modes = 1;
+    }
+  else if (c == mode->mode_weight)
+    mode->n_modes++;
+}
+
+struct mode *
+mode_create (void)
+{
+  struct mode *mode = xmalloc (sizeof *mode);
+  *mode = (struct mode) {
+    .parent = {
+      .parent = {
+        mode_destroy,
+      },
+      .accumulate = mode_accumulate,
+    },
+    .mode = SYSMIS,
+  };
+  return mode;
+}