null_val.c File Reference

Raster Library - NULL value management. More...

#include <string.h>
#include <grass/gis.h>
#include <grass/raster.h>
#include <grass/glocale.h>

Include dependency graph for null_val.c:

Go to the source code of this file.

Functions
void	Rast__set_null_value (void *rast, int numVals, int null_is_zero, RASTER_MAP_TYPE data_type)
	To set one or more raster values to null. More...
void	Rast_set_null_value (void *buf, int numVals, RASTER_MAP_TYPE data_type)
	To set one or more raster values to null. More...
void	Rast_set_c_null_value (CELL *cellVals, int numVals)
	To set a number of CELL raster values to NULL. More...
void	Rast_set_f_null_value (FCELL *fcellVals, int numVals)
	To set a number of FCELL raster values to NULL. More...
void	Rast_set_d_null_value (DCELL *dcellVals, int numVals)
	To set a number of DCELL raster values to NULL. More...
int	Rast_is_null_value (const void *rast, RASTER_MAP_TYPE data_type)
	To check if a raster value is set to NULL. More...
void	Rast_insert_null_values (void *rast, char *null_row, int ncols, RASTER_MAP_TYPE data_type)
	To check if a CELL raster value is set to NULL. More...
void	Rast_insert_c_null_values (CELL *cellVal, char *null_row, int ncols)
	To insert null values into an integer raster map (CELL) More...
void	Rast_insert_f_null_values (FCELL *fcellVal, char *null_row, int ncols)
	To insert null values into an floating-point raster map (FCELL) More...
void	Rast_insert_d_null_values (DCELL *dcellVal, char *null_row, int ncols)
	To insert null values into an floating-point raster map (FCELL) More...
int	Rast__check_null_bit (const unsigned char *flags, int bit_num, int n)
	Check NULL. More...
int	G__set_flags_from_01_random (const char *zero_ones, unsigned char *flags, int col, int n, int ncols)
	Given array of 0/1 of length n starting from column. More...
void	Rast__convert_01_flags (const char *zero_ones, unsigned char *flags, int n)
	? More...
void	Rast__convert_flags_01 (char *zero_ones, const unsigned char *flags, int n)
	? More...
void	Rast__init_null_bits (unsigned char *flags, int cols)
	? More...

Detailed Description

Raster Library - NULL value management.

To provide functionality to handle NULL values for data types CELL, FCELL, and DCELL. May need more...

(C) 2001-2009 GRASS Development Team

This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details.

Author

Original author unknown - probably CERL

Justin Hickey - Thailand - jhick.nosp@m.ey@h.nosp@m.pcc.n.nosp@m.ecte.nosp@m.c.or..nosp@m.th

Definition in file null_val.c.

Function Documentation

G__set_flags_from_01_random()

int G__set_flags_from_01_random	(	const char *	zero_ones,
		unsigned char *	flags,
		int	col,
		int	n,
		int	ncols
	)

Given array of 0/1 of length n starting from column.

Note: Only for internal use.

Given array of 0/1 of length n starting from column set the corresponding bits of flags; total number of bits in flags is ncols.

Parameters

zero_ones
flags
col
n
ncols

Returns

0

1

Definition at line 374 of file null_val.c.

References count, Rast__check_null_bit(), Rast__convert_01_flags(), and Rast__null_bitstream_size().

Rast__check_null_bit()

int Rast__check_null_bit	(	const unsigned char *	flags,
		int	bit_num,
		int	n
	)

Check NULL.

Note: Only for internal use.

Parameters

flags	null bitmap
bit_num	index of bit to check
n	size of null bitmap (in bits)

Returns

1 if set, 0 if unset

Definition at line 338 of file null_val.c.

References G_fatal_error().

Referenced by G__set_flags_from_01_random().

Rast__convert_01_flags()

void Rast__convert_01_flags	(	const char *	zero_ones,
		unsigned char *	flags,
		int	n
	)

?

Note: Only for internal use.

Parameters

zero_ones
flags
n

Definition at line 423 of file null_val.c.

References count, and Rast__null_bitstream_size().

Referenced by G__set_flags_from_01_random().

Rast__convert_flags_01()

void Rast__convert_flags_01	(	char *	zero_ones,
		const unsigned char *	flags,
		int	n
	)

?

Note: Only for internal use.

Parameters

zero_ones
flags
n

Definition at line 461 of file null_val.c.

References count, and Rast__null_bitstream_size().

Rast__init_null_bits()

void Rast__init_null_bits	(	unsigned char *	flags,
		int	cols
	)

?

Note: Only for internal use.

Parameters

flags
cols

Definition at line 495 of file null_val.c.

References Rast__null_bitstream_size().

Rast__set_null_value()

void Rast__set_null_value	(	void *	rast,
		int	numVals,
		int	null_is_zero,
		RASTER_MAP_TYPE	data_type
	)

To set one or more raster values to null.

It also sets null to zero if null_is_zero is TRUE.

Parameters

rast	pointer to values to set to null
numVals	number of values to set to null
null_is_zero	flag to indicate if NULL = 0
data_type	type of raster - CELL, FCELL, DCELL

Definition at line 80 of file null_val.c.

References G_zero(), Rast_cell_size(), and Rast_set_null_value().

Rast_insert_c_null_values()

void Rast_insert_c_null_values	(	CELL *	cellVal,
		char *	null_row,
		int	ncols
	)

To insert null values into an integer raster map (CELL)

For each of the count flags which is true(!=0), set the corresponding cell to the NULL value.

Parameters

rast	pointer raster values
null_row	null row
ncols	number of columns

Definition at line 295 of file null_val.c.

Rast_insert_d_null_values()

void Rast_insert_d_null_values	(	DCELL *	dcellVal,
		char *	null_row,
		int	ncols
	)

To insert null values into an floating-point raster map (FCELL)

For each for the count flag which is true(!=0), set the corresponding dcell to the NULL value.

Parameters

dcellVal	pointer raster values
null_row	null row
ncols	number of columns

Definition at line 322 of file null_val.c.

Rast_insert_f_null_values()

void Rast_insert_f_null_values	(	FCELL *	fcellVal,
		char *	null_row,
		int	ncols
	)

To insert null values into an floating-point raster map (FCELL)

Parameters

fcellVal	pointer raster values
null_row	null row
ncols	number of columns

Definition at line 307 of file null_val.c.

Rast_insert_null_values()

void Rast_insert_null_values	(	void *	rast,
		char *	null_row,
		int	ncols,
		RASTER_MAP_TYPE	data_type
	)

To check if a CELL raster value is set to NULL.

Returns 1 if cell is NULL, 0 otherwise. This will test if the value cell is the largest int.

Parameters

cellVal

CELL raster value to check

Returns

TRUE if CELL raster value is NULL

FALSE otherwise

To check if a FCELL raster value is set to NULL

Returns 1 if fcell is NULL, 0 otherwise. This will test if the value fcell is a NaN. It isn't good enough to test for a particular NaN bit pattern since the machine code may change this bit pattern to a different NaN. The test will be

if(fcell==0.0) return 0;
if(fcell>0.0) return 0;
if(fcell<0.0) return 0;
return 1;

or (as suggested by Mark Line)

return (fcell != fcell);

Parameters

fcellVal

FCELL raster value to check

Returns

TRUE if FCELL raster value is NULL

FALSE otherwise

To check if a DCELL raster value is set to NULL

Returns 1 if dcell is NULL, 0 otherwise. This will test if the value dcell is a NaN. Same test as in Rast_is_f_null_value().

Parameters

dcellVal

DCELL raster value to check

Returns

TRUE if DCELL raster value is NULL

FALSE otherwise

To insert null values into a map.

• If the data_type is CELL_TYPE, calls Rast_insert_c_null_values()
• If the data_type is FCELL_TYPE, calls Rast_insert_f_null_values()
• If the data_type is DCELL_TYPE, calls Rast_insert_d_null_values()

Parameters

rast	pointer raster values
null_row	null row
ncols	number of columns
data_type	type of raster - CELL, FCELL, DCELL

Definition at line 279 of file null_val.c.

Rast_is_null_value()

int Rast_is_null_value	(	const void *	rast,
		RASTER_MAP_TYPE	data_type
	)

To check if a raster value is set to NULL.

• If the data_type is CELL_TYPE, calls Rast_is_c_null_value()
• If the data_type is FCELL_TYPE, calls Rast_is_f_null_value()
• If the data_type is DCELL_TYPE, calls Rast_is_d_null_value()

Parameters

rast	raster value to check
data_type	type of raster - CELL, FCELL, DCELL

Returns

TRUE if raster value is NULL

FALSE otherwise

Definition at line 179 of file null_val.c.

References CELL_TYPE, DCELL_TYPE, FALSE, FCELL_TYPE, G_warning(), Rast_is_c_null_value, Rast_is_d_null_value, and Rast_is_f_null_value.

Referenced by Rast_get_f_value(), Rast_get_vrt_row(), Rast_map_to_img_str(), Rast_raster_cmp(), and Rast_row_update_fp_range().

Rast_set_c_null_value()

void Rast_set_c_null_value	(	CELL *	cellVals,
		int	numVals
	)

To set a number of CELL raster values to NULL.

Parameters

cellVals	pointer to CELL values to set to null
numVals	number of values to set to null

Definition at line 124 of file null_val.c.

Referenced by N_copy_array_2d(), Rast_fpreclass_perform_di(), Rast_fpreclass_perform_fi(), Rast_fpreclass_perform_ii(), Rast_get_range_min_max(), Rast_init_range(), Rast_quant_get_limits(), Rast_quant_perform_d(), Rast_quant_perform_f(), and Rast_set_null_value().

Rast_set_d_null_value()

void Rast_set_d_null_value	(	DCELL *	dcellVals,
		int	numVals
	)

To set a number of DCELL raster values to NULL.

Parameters

dcellVals	pointer to DCELL values to set to null
numVals	number of values to set to null

Definition at line 155 of file null_val.c.

Referenced by c_ave(), c_intr(), c_kurt(), c_max(), c_maxx(), c_median(), c_min(), c_minx(), c_quant(), c_range(), c_skew(), c_stddev(), c_sum(), c_var(), N_copy_array_2d(), Rast_fpreclass_perform_dd(), Rast_fpreclass_perform_fd(), Rast_fpreclass_perform_id(), Rast_get_fp_range_min_max(), Rast_get_ith_d_cat(), Rast_init_fp_range(), Rast_quant_get_limits(), Rast_set_null_value(), w_ave(), w_kurt(), w_max(), w_median(), w_min(), w_quant(), w_skew(), w_stddev(), w_sum(), and w_var().

Rast_set_f_null_value()

void Rast_set_f_null_value	(	FCELL *	fcellVals,
		int	numVals
	)

To set a number of FCELL raster values to NULL.

Parameters

fcellVals	pointer to FCELL values to set to null
numVals	number of values to set to null

Definition at line 138 of file null_val.c.

Referenced by N_copy_array_2d(), Rast_fpreclass_perform_df(), Rast_fpreclass_perform_ff(), Rast_fpreclass_perform_if(), Rast_get_f_value(), and Rast_set_null_value().

Rast_set_null_value()

void Rast_set_null_value	(	void *	buf,
		int	numVals,
		RASTER_MAP_TYPE	data_type
	)

To set one or more raster values to null.

Parameters

buf	pointer to values to set to null
numVals	number of values to set to null
data_type	type of raster - CELL, FCELL, DCELL

Definition at line 98 of file null_val.c.

References _, CELL_TYPE, DCELL_TYPE, FCELL_TYPE, G_warning(), Rast_set_c_null_value(), Rast_set_d_null_value(), and Rast_set_f_null_value().

Referenced by Rast__set_null_value(), Rast_get_vrt_row(), and Rast_set_f_value().