GNU Astronomy Utilities

10.3.5.3 Arrays of datasets

Gnuastro’s generic data container (gal_data_t) is a very versatile structure that can be used in many higher-level contexts. One such higher-level construct is an array of gal_data_t structures to simplify the allocation (and later cleaning) of several gal_data_ts that are related.

For example, each column in a table is usually represented by one gal_data_t (so it has its own name, numeric data type, units and etc). A table (with many columns) can be seen as an array of gal_data_ts (when the number of columns is known a-priori). The functions below are defined to create a cleared array of data structures and to free them in the end. These functions are declared in gnuastro/data.h which is also visible from the function names (see Gnuastro library).

Function:
gal_data_t *
gal_data_array_calloc (size_t size)

Allocate an array of gal_data_t with size elements. This function will also initialize all the values (NULL for pointers and 0 for other types). You can use gal_data_initialize to fill each element of the array afterwards. The following code snippet is one example of doing this.

size_t i;
gal_data_t *dataarr;
dataarr=gal_data_array_calloc(10);
for(i=0;i<10;++i) gal_data_initialize(&dataarr[i], ...);
...
gal_data_array_free(dataarr, 10, 1);

Function:
void
gal_data_array_free (gal_data_t *dataarr, size_t num, int free_array)

Free all the num elements within dataarr and the actual allocated array. If free_array is not zero, then the array element of all the datasets will also be freed, see Generic data container (gal_data_t).

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GNU Astronomy Utilities 0.5 manual, December 2017.