Iterating on latitude/longitude/values

Data Structures
struct	codes_iterator
struct	codes_nearest

Functions
codes_iterator *	codes_grib_iterator_new (codes_handle *h, unsigned long flags, int *error)
	Create a new iterator from a GRIB handle, using current geometry and values. More...
int	codes_grib_get_data (codes_handle *h, double *lats, double *lons, double *values)
	Get latitude/longitude and data values. More...
int	codes_grib_iterator_next (codes_iterator *i, double *lat, double *lon, double *value)
	Get the next value from an iterator. More...
int	codes_grib_iterator_previous (codes_iterator *i, double *lat, double *lon, double *value)
	Get the previous value from an iterator. More...
int	codes_grib_iterator_has_next (codes_iterator *i)
	Test procedure for values in an iterator. More...
int	codes_grib_iterator_reset (codes_iterator *i)
	Test procedure for values in an iterator. More...
int	codes_grib_iterator_delete (codes_iterator *i)
	Frees an iterator from memory. More...
codes_nearest *	codes_grib_nearest_new (codes_handle *h, int *error)
	Create a new nearest from a handle, using current geometry . More...
int	codes_grib_nearest_find (codes_nearest *nearest, codes_handle *h, double inlat, double inlon, unsigned long flags, double *outlats, double *outlons, double *values, double *distances, int *indexes, size_t *len)
	Find the 4 nearest points of a latitude longitude point. More...
int	codes_grib_nearest_delete (codes_nearest *nearest)
	Frees an nearest from memory. More...
int	codes_grib_nearest_find_multiple (codes_handle *h, int is_lsm, double *inlats, double *inlons, long npoints, double *outlats, double *outlons, double *values, double *distances, int *indexes)
	Find the nearest point of a set of points whose latitudes and longitudes are given in the inlats, inlons arrays respectively. More...

Detailed Description

Function Documentation

int codes_grib_get_data	(	codes_handle *	h,
		double *	lats,
		double *	lons,
		double *	values
	)

Get latitude/longitude and data values.

The Latitudes, longitudes and values arrays must be properly allocated by the caller. Their required dimension can be obtained by getting the value of the integer key "numberOfPoints".

Parameters

h	: handle from which geography and data values are taken
lats	: returned array of latitudes
lons	: returned array of longitudes
values	: returned array of data values

Returns

0 if OK, integer value on error

int codes_grib_iterator_delete

(

codes_iterator *

i

)

Frees an iterator from memory.

Parameters

i	: the iterator

Returns

0 if OK, integer value on error

int codes_grib_iterator_has_next

(

codes_iterator *

i

)

Test procedure for values in an iterator.

Parameters

i	: the iterator

Returns

boolean, 1 if the iterator still nave next values, 0 otherwise

codes_iterator* codes_grib_iterator_new	(	codes_handle *	h,
		unsigned long	flags,
		int *	error
	)

Create a new iterator from a GRIB handle, using current geometry and values.

Parameters

h	: the handle from which the iterator will be created
flags	: flags for future use.
error	: error code

Returns

the new iterator, NULL if no iterator can be created

int codes_grib_iterator_next	(	codes_iterator *	i,
		double *	lat,
		double *	lon,
		double *	value
	)

Get the next value from an iterator.

Parameters

i	: the iterator
lat	: on output latitude in degree
lon	: on output longitude in degree
value	: on output value of the point

Returns

positive value if successful, 0 if no more data are available

int codes_grib_iterator_previous	(	codes_iterator *	i,
		double *	lat,
		double *	lon,
		double *	value
	)

Get the previous value from an iterator.

Parameters

i	: the iterator
lat	: on output latitude in degree
lon	: on output longitude in degree
value	: on output value of the point*

Returns

positive value if successful, 0 if no more data are available

int codes_grib_iterator_reset

(

codes_iterator *

i

)

Test procedure for values in an iterator.

Parameters

i	: the iterator

Returns

0 if OK, integer value on error

int codes_grib_nearest_delete

(

codes_nearest *

nearest

)

Frees an nearest from memory.

Parameters

nearest

: the nearest

Returns

0 if OK, integer value on error

int codes_grib_nearest_find	(	codes_nearest *	nearest,
		codes_handle *	h,
		double	inlat,
		double	inlon,
		unsigned long	flags,
		double *	outlats,
		double *	outlons,
		double *	values,
		double *	distances,
		int *	indexes,
		size_t *	len
	)

Find the 4 nearest points of a latitude longitude point.

The flags are provided to speed up the process of searching. If you are sure that the point you are asking for is not changing from a call to another you can use CODES_NEAREST_SAME_POINT. The same is valid for the grid. Flags can be used together doing a bitwise OR. The distances are given in kilometres.

Parameters

nearest	: nearest structure
h	: handle from which geography and data values are taken
inlat	: latitude of the point to search for
inlon	: longitude of the point to search for
flags	: CODES_NEAREST_SAME_POINT, CODES_NEAREST_SAME_GRID
outlats	: returned array of latitudes of the nearest points
outlons	: returned array of longitudes of the nearest points
values	: returned array of data values of the nearest points
distances	: returned array of distances from the nearest points
indexes	: returned array of indexes of the nearest points
len	: size of the arrays

Returns

0 if OK, integer value on error

int codes_grib_nearest_find_multiple	(	codes_handle *	h,
		int	is_lsm,
		double *	inlats,
		double *	inlons,
		long	npoints,
		double *	outlats,
		double *	outlons,
		double *	values,
		double *	distances,
		int *	indexes
	)

Find the nearest point of a set of points whose latitudes and longitudes are given in the inlats, inlons arrays respectively.

If the flag is_lsm is 1 the nearest land point is returned and the grib passed as handle (h) is considered a land sea mask. The land nearest point is the nearest point with land sea mask value>=0.5. If no nearest land points are found the nearest value is returned. If the flag is_lsm is 0 the nearest point is returned. values, distances, indexes (in the "values" array) for the nearest points (ilons,ilats) are returned. The distances are given in kilometres.

Parameters

h	: handle from which geography and data values are taken
is_lsm	: lsm flag (1-> nearest land, 0-> nearest)
inlats	: latitudes of the points to search for
inlons	: longitudes of the points to search for
npoints	: number of points (size of the inlats,inlons,outlats,outlons,values,distances,indexes arrays)
outlats	: returned array of latitudes of the nearest points
outlons	: returned array of longitudes of the nearest points
values	: returned array of data values of the nearest points
distances	: returned array of distances from the nearest points
indexes	: returned array of indexes of the nearest points

Returns

0 if OK, integer value on error

codes_nearest* codes_grib_nearest_new	(	codes_handle *	h,
		int *	error
	)

Create a new nearest from a handle, using current geometry .

Parameters

h	: the handle from which the iterator will be created
error	: error code

Returns

the new nearest, NULL if no nearest can be created