GRIB-382: grib_get_data also for C and Python: Exposed the C function and added C example

examples/C/get_data.c

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2005-2013 ECMWF.
+ *
+ * This software is licensed under the terms of the Apache Licence Version 2.0
+ * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
+ *
+ * In applying this licence, ECMWF does not waive the privileges and immunities granted to it by
+ * virtue of its status as an intergovernmental organisation nor does it submit to any jurisdiction.
+ */
+
+/*
+ * C Implementation: get_data
+ *
+ * Description: how to get lat/lon/values.
+ *
+ */
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "grib_api.h"
+
+int main (int argc, char **argv)
+{
+    int err = 0;
+    size_t i = 0;
+    FILE *in = NULL;
+    const char *filename = "../../data/reduced_latlon_surface.grib1";
+    grib_handle *h = NULL;
+    long numberOfPoints = 0;
+    const double missing = 9999.0;
+    double *lats, *lons, *values;       /* arrays */
+
+    in = fopen (filename, "r");
+    if (!in) {
+        printf ("ERROR: unable to open input file %s\n", filename);
+        return 1;
+    }
+
+    /* create new handle from a message in a file */
+    h = grib_handle_new_from_file (0, in, &err);
+    if (h == NULL) {
+        printf ("Error: unable to create handle from file %s\n", filename);
+        return 1;
+    }
+
+    GRIB_CHECK (grib_get_long (h, "numberOfPoints", &numberOfPoints), 0);
+    GRIB_CHECK (grib_set_double (h, "missingValue", missing), 0);
+
+    lats = (double *) malloc (numberOfPoints * sizeof (double));
+    if (!lats) {
+        printf ("unable to allocate %ld bytes\n", (long) (numberOfPoints * sizeof (double)));
+        return 1;
+    }
+    lons = (double *) malloc (numberOfPoints * sizeof (double));
+    if (!lons) {
+        printf ("unable to allocate %ld bytes\n", (long) (numberOfPoints * sizeof (double)));
+        return 1;
+    }
+    values = (double *) malloc (numberOfPoints * sizeof (double));
+    if (!values) {
+        printf ("unable to allocate %ld bytes\n", (long) (numberOfPoints * sizeof (double)));
+        return 1;
+    }
+
+    GRIB_CHECK (grib_get_data (h, lats, lons, values, NULL), 0);
+
+    for (i = 0; i < numberOfPoints; ++i) {
+        if (values[i] != missing) {
+            printf ("%f %f %f\n", lats[i], lons[i], values[i]);
+        }
+    }
+
+    free (lats);
+    free (lons);
+    free (values);
+    grib_handle_delete (h);
+
+    fclose (in);
+    return 0;
+}

examples/C/get_data.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+# Copyright 2005-2013 ECMWF.
+#
+# This software is licensed under the terms of the Apache Licence Version 2.0
+# which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# In applying this licence, ECMWF does not waive the privileges and immunities granted to it by
+# virtue of its status as an intergovernmental organisation nor does it submit to any jurisdiction.
+
+. ./include.sh
+
+${examples_dir}get_data > /dev/null