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//------------------------------------------------------------------------------
// GB_ijsort: sort an index array I and remove duplicates
//------------------------------------------------------------------------------
// SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2022, All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
//------------------------------------------------------------------------------
// Sort an index array and remove duplicates:
/*
[I1 I1k] = sort (I) ;
Iduplicate = [(I1 (1:end-1) == I1 (2:end)), false] ;
I2 = I1 (~Iduplicate) ;
I2k = I1k (~Iduplicate) ;
*/
#include "GB_ij.h"
#include "GB_sort.h"
#define GB_FREE_WORKSPACE \
{ \
GB_FREE_WORK (&Work, Work_size) ; \
}
GrB_Info GB_ijsort
(
const GrB_Index *restrict I, // size ni, where ni > 1 always holds
int64_t *restrict p_ni, // : size of I, output: # of indices in I2
GrB_Index *restrict *p_I2, // size ni2, where I2 [0..ni2-1]
// contains the sorted indices with duplicates removed.
size_t *I2_size_handle,
GrB_Index *restrict *p_I2k, // output array of size ni2
size_t *I2k_size_handle,
GB_Context Context
)
{
//--------------------------------------------------------------------------
// check inputs
//--------------------------------------------------------------------------
GrB_Info info ;
ASSERT (I != NULL) ;
ASSERT (p_ni != NULL) ;
ASSERT (p_I2 != NULL) ;
ASSERT (p_I2k != NULL) ;
//--------------------------------------------------------------------------
// get inputs
//--------------------------------------------------------------------------
GrB_Index *Work = NULL ; size_t Work_size = 0 ;
GrB_Index *restrict I2 = NULL ; size_t I2_size = 0 ;
GrB_Index *restrict I2k = NULL ; size_t I2k_size = 0 ;
int64_t ni = *p_ni ;
ASSERT (ni > 1) ;
int ntasks = 0 ;
//--------------------------------------------------------------------------
// determine the number of threads to use
//--------------------------------------------------------------------------
GB_GET_NTHREADS_MAX (nthreads_max, chunk, Context) ;
int nthreads = GB_nthreads (ni, chunk, nthreads_max) ;
//--------------------------------------------------------------------------
// determine number of tasks to create
//--------------------------------------------------------------------------
ntasks = (nthreads == 1) ? 1 : (32 * nthreads) ;
ntasks = GB_IMIN (ntasks, ni) ;
ntasks = GB_IMAX (ntasks, 1) ;
//--------------------------------------------------------------------------
// allocate workspace
//--------------------------------------------------------------------------
Work = GB_MALLOC_WORK (2*ni + ntasks + 1, GrB_Index, &Work_size) ;
if (Work == NULL)
{
// out of memory
return (GrB_OUT_OF_MEMORY) ;
}
GrB_Index *restrict I1 = Work ; // size ni
GrB_Index *restrict I1k = Work + ni ; // size ni
int64_t *restrict Count = (int64_t *) (Work + 2*ni) ; // size ntasks+1
//--------------------------------------------------------------------------
// copy I into I1 and construct I1k
//--------------------------------------------------------------------------
GB_memcpy (I1, I, ni * sizeof (GrB_Index), nthreads) ;
int64_t k ;
#pragma omp parallel for num_threads(nthreads) schedule(static)
for (k = 0 ; k < ni ; k++)
{
// the key is selected so that the last duplicate entry comes first in
// the sorted result. It must be adjusted later, so that the kth entry
// has a key equal to k.
I1k [k] = (ni-k) ;
}
//--------------------------------------------------------------------------
// sort [I1 I1k]
//--------------------------------------------------------------------------
info = GB_msort_2 ((int64_t *) I1, (int64_t *) I1k, ni, nthreads) ;
if (info != GrB_SUCCESS)
{
// out of memory
GB_FREE_WORKSPACE ;
return (GrB_OUT_OF_MEMORY) ;
}
//--------------------------------------------------------------------------
// count unique entries in I1
//--------------------------------------------------------------------------
int tid ;
#pragma omp parallel for num_threads(nthreads) schedule(dynamic,1)
for (tid = 0 ; tid < ntasks ; tid++)
{
int64_t kfirst, klast, my_count = (tid == 0) ? 1 : 0 ;
GB_PARTITION (kfirst, klast, ni, tid, ntasks) ;
for (int64_t k = GB_IMAX (kfirst,1) ; k < klast ; k++)
{
if (I1 [k-1] != I1 [k])
{
my_count++ ;
}
}
Count [tid] = my_count ;
}
GB_cumsum (Count, ntasks, NULL, 1, NULL) ;
int64_t ni2 = Count [ntasks] ;
//--------------------------------------------------------------------------
// allocate the result I2
//--------------------------------------------------------------------------
I2 = GB_MALLOC_WORK (ni2, GrB_Index, &I2_size) ;
I2k = GB_MALLOC_WORK (ni2, GrB_Index, &I2k_size) ;
if (I2 == NULL || I2k == NULL)
{
// out of memory
GB_FREE_WORKSPACE ;
GB_FREE_WORK (&I2, I2_size) ;
GB_FREE_WORK (&I2k, I2k_size) ;
return (GrB_OUT_OF_MEMORY) ;
}
//--------------------------------------------------------------------------
// construct the new list I2 from I1, removing duplicates
//--------------------------------------------------------------------------
#pragma omp parallel for num_threads(nthreads) schedule(dynamic,1)
for (tid = 0 ; tid < ntasks ; tid++)
{
int64_t kfirst, klast, k2 = Count [tid] ;
GB_PARTITION (kfirst, klast, ni, tid, ntasks) ;
if (tid == 0)
{
// the first entry in I1 is never a duplicate
I2 [k2] = I1 [0] ;
I2k [k2] = (ni - I1k [0]) ;
k2++ ;
}
for (int64_t k = GB_IMAX (kfirst,1) ; k < klast ; k++)
{
if (I1 [k-1] != I1 [k])
{
I2 [k2] = I1 [k] ;
I2k [k2] = ni - I1k [k] ;
k2++ ;
}
}
}
//--------------------------------------------------------------------------
// check result: compare with single-pass, single-threaded algorithm
//--------------------------------------------------------------------------
#ifdef GB_DEBUG
{
int64_t ni1 = 1 ;
I1k [0] = ni - I1k [0] ;
for (int64_t k = 1 ; k < ni ; k++)
{
if (I1 [ni1-1] != I1 [k])
{
I1 [ni1] = I1 [k] ;
I1k [ni1] = ni - I1k [k] ;
ni1++ ;
}
}
ASSERT (ni1 == ni2) ;
for (int64_t k = 0 ; k < ni1 ; k++)
{
ASSERT (I1 [k] == I2 [k]) ;
ASSERT (I1k [k] == I2k [k]) ;
}
}
#endif
//--------------------------------------------------------------------------
// free workspace and return the new sorted list
//--------------------------------------------------------------------------
GB_FREE_WORKSPACE ;
*(p_I2 ) = (GrB_Index *) I2 ; (*I2_size_handle ) = I2_size ;
*(p_I2k) = (GrB_Index *) I2k ; (*I2k_size_handle) = I2k_size ;
*(p_ni ) = (int64_t ) ni2 ;
return (GrB_SUCCESS) ;
}
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