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Fix issue #3612 #4127

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merged 16 commits into from
Jan 29, 2018
Merged

Fix issue #3612 #4127

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549e646
First attempt at fixing #3612
Jan 25, 2018
574922b
Attempt #1 to fix segfault
Jan 27, 2018
9e8e5e2
Revert "Attempt #1 to fix segfault"
Jan 27, 2018
214c8e4
segafault fix attempt no2
Jan 27, 2018
c801712
Whitespace fix
Jan 27, 2018
be69f9a
Formatting fix
Jan 27, 2018
70ab831
Added that single space character to make the style checker happy
Jan 27, 2018
599d4ed
Added unref for the two subset stacks
Jan 27, 2018
02ed8a9
adds unit test functions for combined kernel subsetting behaviour. Fi…
Jan 28, 2018
72dfbb9
Formatting
Jan 28, 2018
deb551f
More formatting changes
Jan 28, 2018
ebea19f
indent fix
Jan 28, 2018
cb0aa15
removed a line to make the style checker happy
Jan 28, 2018
3205bde
Replaced explicit casts with dynamic casts
Jan 28, 2018
d831611
tab fixes
Jan 28, 2018
a8a50ad
:(
Jan 28, 2018
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25 changes: 25 additions & 0 deletions src/shogun/kernel/CombinedKernel.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -147,6 +147,31 @@ bool CCombinedKernel::init(CFeatures* l, CFeatures* r)
SG_DEBUG("Initializing 0x%p - \"%s\" (skipping init, this is a CUSTOM kernel)\n", this, k->get_name())
if (!k->has_features())
SG_ERROR("No kernel matrix was assigned to this Custom kernel\n")

// extract row & column subset indices from combined features
auto lhs_subset_stack = ((CCombinedFeatures*)l)->get_subset_stack();
auto rhs_subset_stack = ((CCombinedFeatures*)r)->get_subset_stack();

if (lhs_subset_stack->has_subsets())
{
auto lhs_subset =
lhs_subset_stack->get_last_subset()->get_subset_idx();
// clear all previous subsets
((CCustomKernel*)k)->remove_all_row_subsets();
// apply new subset
((CCustomKernel*)k)->add_row_subset(lhs_subset);
}

if (rhs_subset_stack->has_subsets())
{
auto rhs_subset =
rhs_subset_stack->get_last_subset()->get_subset_idx();
// clear all previous subsets
((CCustomKernel*)k)->remove_all_col_subsets();
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I think you shouldn’t clear the subsets here.
This should happen from outside (and only the last one) as otherwise you might remove stuff a user has set previously

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I operated under the assumption that the subset should be maintained in sync with the combinedfeatures used to init the combinedkernel. Normally, as per my understanding, the subset for the subkernels is obtained from the features used to init them. (The init(features l, features r) method of custom kernel in fact clears the subsets).
As the custom kernel has no features in the 1st place, I attempted to replicate what an init() would do if it had features.
Alternative approach: I could instantiate CIndexFeatures using lhs_subset/rhs_subset, then init the custom kernel using these. This might actually be a better approach, on a second though

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Update: There seems to be an inconsistency within CCustomKernel::init(CFeatures* l, CFeatures* r).
Namely, if l & r are of type CIndexFeatures the normalizer doesnt get called, see following block

	if (l->get_feature_class()==C_INDEX && r->get_feature_class()==C_INDEX)
	{
		CIndexFeatures* l_idx = (CIndexFeatures*)l;
		CIndexFeatures* r_idx = (CIndexFeatures*)r;

		remove_all_col_subsets();
		remove_all_row_subsets();

		add_row_subset(l_idx->get_feature_index());
		add_col_subset(r_idx->get_feature_index());

		lhs_equals_rhs=m_is_symmetric;

		return true;
	}

	/* For other types of CFeatures do the default actions below */
	CKernel::init(l, r);

	lhs_equals_rhs=m_is_symmetric;

	SG_DEBUG("num_vec_lhs: %d vs num_rows %d\n", l->get_num_vectors(), kmatrix.num_rows)
	SG_DEBUG("num_vec_rhs: %d vs num_cols %d\n", r->get_num_vectors(), kmatrix.num_cols)
	ASSERT(l->get_num_vectors()==kmatrix.num_rows)
	ASSERT(r->get_num_vectors()==kmatrix.num_cols)
	return init_normalizer();

Is this intentional or not?

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Most things in there were written in demand if one specific use case, so probably no.

I think everything should be consistent between normal kernels and custom kernels.

So maybe we keep it like this.

Memory check is important before merging though

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I'm not 100% certain what do you mean re: consistency; could you please clarify it to me, perhaps on irc?

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Sorry. I meant do it the same way for custom kernels as for normal kernels (clearing the stack)

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OK, so keep the current method, rather than providing dummy indexfeatures, and calling the customkernels init on those? (+ and fix the memory issues)

// apply new subset
((CCustomKernel*)k)->add_col_subset(rhs_subset);
}

if (k->get_num_vec_lhs() != num_lhs)
SG_ERROR("Number of lhs-feature vectors (%d) not match with number of rows (%d) of custom kernel\n", num_lhs, k->get_num_vec_lhs())
if (k->get_num_vec_rhs() != num_rhs)
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