Added function gridInqUvRelativeToGrid() (patch from Michal Koutek, KMNI).

ChangeLog

@@ -2,6 +2,10 @@
 
 	* Version 1.8.1 released
 
+2017-02-24  Uwe Schulzweida
+
+	* Added function gridInqUvRelativeToGrid() (patch from Michal Koutek, KMNI)
+
 2017-02-22  Uwe Schulzweida
 
 	* CDI_CHUNK_AUTO: set chunk_size_max to 65536

src/cdi.h

@@ -964,6 +964,8 @@ void    gridChangeType(int gridID, int gridtype);
 void    gridDefComplexPacking(int gridID, int lpack);
 int     gridInqComplexPacking(int gridID);
 
+int     gridInqUvRelativeToGrid(int gridID);
+
 /* ZAXIS routines */
 
 void    zaxisName(int zaxistype, char *zaxisname);

src/gribapi_utilities.c

@@ -713,6 +713,11 @@ void gribapiGetGrid(grib_handle *gh, grid_t *grid)
       Error("Unsupported grid type: %s", gridNamePtr(gridtype));
     }
 
+  if ( gridtype == GRID_LONLAT || gridtype == GRID_CURVILINEAR || gridtype == GRID_LCC )
+    {
+      GRIB_CHECK(grib_get_long(gh, "uvRelativeToGrid", &grid->uvRelativeToGrid), 0);
+    }
+
   grid->type  = gridtype;
   grid->projtype  = projtype;
 }

src/grid.c

@@ -157,6 +157,7 @@ void grid_init(grid_t *gridptr)
   gridptr->vtable        = &cdiGridVtable;
   gridptr->atts.nalloc   = MAX_ATTRIBUTES;
   gridptr->atts.nelems   = 0;
+  gridptr->uvRelativeToGrid      = 0;   // Some models deliver wind U,V relative to the grid-cell
 }
 
 
@@ -2217,6 +2218,11 @@ bool gridCompare(int gridID, const grid_t *grid, bool coord_compare)
 	}
     }
 
+  if ( (grid->uvRelativeToGrid != gridInqUvRelativeToGrid(gridID)) )
+    {
+      // often grid definition may differ in UV-relativeToGrid
+      differ = 1;
+    }
   return differ;
 }
 
@@ -2277,6 +2283,7 @@ int gridCompareP(void *gridptr1, void *gridptr2)
   if ( IS_NOT_EQUAL(g1->lcc.lat2      , g2->lcc.lat2)      ) return differ;
   if ( IS_NOT_EQUAL(g1->lcc.xinc      , g2->lcc.xinc)      ) return differ;
   if ( IS_NOT_EQUAL(g1->lcc.yinc      , g2->lcc.yinc)      ) return differ;
+  if ( IS_NOT_EQUAL(g1->uvRelativeToGrid     , g2->uvRelativeToGrid)     ) return differ;
 
   const double *restrict g1_xvals = g1->vtable->inqXValsPtr(g1),
                *restrict g2_xvals = g2->vtable->inqXValsPtr(g2);
@@ -2615,6 +2622,7 @@ int gridGenerate(const grid_t *grid)
   gridptr->lcc.scanflag = grid->lcc.scanflag;
   gridptr->number = grid->number;
   gridptr->position = grid->position;
+  gridptr->uvRelativeToGrid       = grid->uvRelativeToGrid;
   memcpy(gridptr->uuid, grid->uuid, CDI_UUID_SIZE);
   if ( gridtype == GRID_UNSTRUCTURED && grid->reference )
     gridDefReference(gridID, grid->reference);
@@ -3926,6 +3934,13 @@ void gridInqUUID(int gridID, unsigned char uuid[CDI_UUID_SIZE])
 }
 
 
+int gridInqUvRelativeToGrid(int gridID)
+{
+  grid_t *gridptr = grid_to_pointer(gridID);
+  return gridptr->uvRelativeToGrid;
+}
+
+
 void cdiGridGetIndexList(unsigned ngrids, int * gridIndexList)
 {
   reshGetResHListOfType(ngrids, gridIndexList, &gridOps);

src/grid.h

@@ -104,6 +104,7 @@ struct grid_t {
   int     np;                     /* number of parallels between a pole and the equator */
   bool    lcomplex;
   bool    hasdims;
+  long uvRelativeToGrid;           /* Some models deliver wind U,V relative to the grid-cell */
   struct gridaxis_t x;
   struct gridaxis_t y;
   const struct gridVirtTable *vtable;