NAME

dssubset.h - DATASET_METHOD subset type

SYNOPSIS

Given an existing DATASET, one can define a new subset of the first data set. The actual subset is determined by a user specifed range. This is useful for incremental techniques applied to huge amounts of data.

#include <dssubset.h>

DSM_SUBSET *dsm_subset(DATASET *dset,
     unsigned start, unsigned len,
     unsigned skip);

void dsm_destroy_subset(DSM_SUBSET *subset);

DESCRIPTION

Type Declarations

The following types are defined in the header file dssubset.h.

DSM_SUBSET

typedef struct DSM_SUBSET {
  DATASET *dset;
  unsigned start;
  unsigned len;
  unsigned skip;
} DSM_SUBSET;

A DSM_SUBSET specifies how to reference a subset of the data in dset. If you were to ask for the i'th pattern of the DATASET wrapped by this structure, in reality you would get the start + i * skip pattern of dset. Also, in the subset, you can only reference len patterns, so the values in these fields should make sense for {dset.}

Function Definitions

The following function prototypes are given in the header file dssubset.h.

DSM_SUBSET *dsm_subset(DATASET *dset,
     unsigned start, unsigned len,
     unsigned skip);

Allocates a new subset, fills up the appropriate fields of the structure, and does a quick sanity check on the supplied values.

void dsm_destroy_subset(DSM_SUBSET *subset);

Free up any memory that was allocated with the allocation routine. The original DATASET that is passed to dsm_subset() is left intact; hence, it is your job to free them up.

AUTHOR

Gary William Flake (gary.flake@usa.net).

SEE ALSO

dsmethod(3), and dataset(3).