mvl_write_hash_vectors: Write hash values for each row

In RMVL: Mappable Vector Library for Handling Large Datasets

Write hash values for each row

Description

This function is passed a list of MVL vectors which are interpreted in data.frame fashion. For each row, i.e. set of vector values with the same index we compute a 64-bit hash value. Identical rows produce identical hash values. The hash values are written into 64-bit integer vector. This function is meant for use with data that is too large to handle comfortably.

Usage

mvl_write_hash_vectors(MVLHANDLE, L, name = NULL)

Arguments

MVLHANDLE	a handle to MVL file produced by mvl_open()
L	list of vector like MVL_OBJECTs
name	if specified add a named entry to MVL file directory

Value

an object of class MVL_OFFSET that describes an offset into this MVL file. MVL offsets are vectors and can be concatenated. They can be written to MVL file directly, or as part of another object such as list.

See Also

mvl_order_vectors, mvl_find_matches, mvl_group, mvl_find_matches, mvl_indexed_copy, mvl_merge, mvl_hash_vectors

Examples

## Not run: 
Mtmp<-mvl_open("tmp_a.mvl", append=TRUE, create=TRUE)
mvl_write_object(Mtmp, runif(100), "vec1")
Mtmp<-mvl_remap(Mtmp)
mvl_write_hash_vectors(Mtmp, list(Mtmp["vec1", ref=TRUE]), "vec1_hash")
Mtmp<-mvl_remap(Mtmp)
print(length(Mtmp["vec1_hash"]))

## End(Not run)

RMVL documentation built on Feb. 23, 2025, 3:01 a.m.