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Added make_sparse_vector_inplace()

This commit is contained in:
Davis King 2013-01-18 22:10:42 -05:00
parent c8b59522e1
commit 170cffad97
3 changed files with 105 additions and 0 deletions
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57
dlib/svm/sparse_vector.h
View File

@ -908,6 +908,63 @@ namespace dlib
return T(temp.begin(), temp.end());
}
// ----------------------------------------------------------------------------------------
template <
typename T
>
void make_sparse_vector_inplace(
T& vect
)
{
vect = make_sparse_vector(vect);
}
// ----------------------------------------------------------------------------------------
template <
typename T,
typename U,
typename alloc
>
void make_sparse_vector_inplace (
std::vector<std::pair<T,U>,alloc>& vect
)
{
if (vect.size() > 0)
{
std::sort(vect.begin(), vect.end());
// merge duplicates
for (unsigned long i = 1; i < vect.size(); ++i)
{
// if we found a duplicate
if (vect[i-1].first == vect[i].first)
{
// now start collapsing and merging the vector
unsigned long j = i-1;
for (unsigned long k = i; k < vect.size(); ++k)
{
if (vect[j].first == vect[k].first)
{
vect[j].second += vect[k].second;
}
else
{
++j;
vect[j] = vect[k];
}
}
// we removed elements when we merged so we need to adjust the size.
vect.resize(j+1);
return;
}
}
}
}
// ----------------------------------------------------------------------------------------
template <typename EXP, typename T, long NR, long NC, typename MM, typename L>

18
dlib/svm/sparse_vector_abstract.h
View File

@ -512,6 +512,24 @@ namespace dlib
will still logically represent the same vector).
!*/
// ----------------------------------------------------------------------------------------
template <
typename T
>
void make_sparse_vector_inplace(
T& vect
);
/*!
requires
- v is an unsorted sparse vector
ensures
- vect == make_sparse_vector(vect)
- This function is just an optimized version of make_sparse_vector(), in
particular, when T is a std::vector<std::pair<>> type it is much more
efficient.
!*/
// ----------------------------------------------------------------------------------------
template <

30
dlib/test/sparse_vector.cpp
View File

@ -110,6 +110,34 @@ namespace
DLIB_TEST(max(abs(r1-r2)) < 1e-15);
}
// ----------------------------------------------------------------------------------------
void test_make_sparse_vector_inplace()
{
std::vector<std::pair<unsigned long,double> > vect;
vect.push_back(make_pair(4,1));
vect.push_back(make_pair(0,1));
vect.push_back(make_pair(4,1));
vect.push_back(make_pair(3,1));
vect.push_back(make_pair(8,1));
vect.push_back(make_pair(8,1));
vect.push_back(make_pair(8,1));
vect.push_back(make_pair(8,1));
make_sparse_vector_inplace(vect);
DLIB_TEST(vect.size() == 4);
DLIB_TEST(vect[0].first == 0);
DLIB_TEST(vect[1].first == 3);
DLIB_TEST(vect[2].first == 4);
DLIB_TEST(vect[3].first == 8);
DLIB_TEST(vect[0].second == 1);
DLIB_TEST(vect[1].second == 1);
DLIB_TEST(vect[2].second == 2);
DLIB_TEST(vect[3].second == 4);
}
// ----------------------------------------------------------------------------------------
class sparse_vector_tester : public tester
@ -129,6 +157,8 @@ namespace
void perform_test (
)
{
test_make_sparse_vector_inplace();
std::map<unsigned int, double> v;
v[4] = 8;
v[2] = -4;