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100 lines
4.3 KiB
Cython
100 lines
4.3 KiB
Cython
"""Knowledge-base for entity or concept linking."""
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from cymem.cymem cimport Pool
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from preshed.maps cimport PreshMap
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from libcpp.vector cimport vector
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from libc.stdint cimport int32_t, int64_t
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from .typedefs cimport attr_t, hash_t
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from .strings cimport hash_string
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# Internal struct, for storage and disambiguation. This isn't what we return
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# to the user as the answer to "here's your entity". It's the minimum number
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# of bits we need to keep track of the answers.
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cdef struct _EntryC:
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# Allows retrieval of one or more vectors.
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# Each element of vector_rows should be an index into a vectors table.
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# Every entry should have the same number of vectors, so we can avoid storing
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# the number of vectors in each knowledge-base struct
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const int32_t* vector_rows
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# Allows retrieval of a struct of non-vector features. We could make this a
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# pointer, but we have 32 bits left over in the struct after prob, so we'd
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# like this to only be 32 bits. We can also set this to -1, for the common
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# case where there are no features.
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int32_t feats_row
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# log probability of entity, based on corpus frequency
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float prob
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cdef class KnowledgeBase:
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cdef Pool mem
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# This maps 64bit keys to 64bit values. Here the key would be a hash of
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# a unique string name for the entity, and the value would be the position
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# of the _EntryC struct in our vector.
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# The PreshMap is pretty space efficient, as it uses open addressing. So
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# the only overhead is the vacancy rate, which is approximately 30%.
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cdef PreshMap _index
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# Each entry takes 128 bits, and again we'll have a 30% or so overhead for
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# over allocation.
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# In total we end up with (N*128*1.3)+(N*128*1.3) bits for N entries.
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# Storing 1m entries would take 41.6mb under this scheme.
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cdef vector[_EntryC] _entries
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# This is the part which might take more space: storing various
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# categorical features for the entries, and storing vectors for disambiguation
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# and possibly usage.
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# If each entry gets a 300-dimensional vector, for 1m entries we would need
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# 1.2gb. That gets expensive fast. What might be better is to avoid learning
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# a unique vector for every entity. We could instead have a compositional
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# model, that embeds different features of the entities into vectors. We'll
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# still want some per-entity features, like the Wikipedia text or entity
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# co-occurrence. Hopefully those vectors can be narrow, e.g. 64 dimensions.
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cdef object _vectors_table
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# It's very useful to track categorical features, at least for output, even
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# if they're not useful in the model itself. For instance, we should be
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# able to track stuff like a person's date of birth or whatever. This can
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# easily make the KB bigger, but if this isn't needed by the model, and it's
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# optional data, we can let users configure a DB as the backend for this.
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cdef object _features_table
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# This should map mention hashes to (entry_id, prob) tuples. The probability
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# should be P(entity | mention), which is pretty important to know.
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# We can pack both pieces of information into a 64-bit value, to keep things
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# efficient.
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cdef object _aliases_table
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def __len__(self):
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return self._entries.size()
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def add_entity(self, name, float prob, vectors=None, features=None, aliases=None):
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# TODO: more friendly check for non-unique name
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if name in self:
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return
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cdef hash_t key = hash_string(name)
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self.c_add_entity(key, prob, self._vectors_table.get_pointer(vectors),
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self._features_table.get(features))
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# TODO: hash the aliases?
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for alias, prob_alias in aliases:
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self._aliases_table.add(alias, key, prob_alias)
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cdef void c_add_entity(self, hash_t key, float prob, const int32_t* vector_rows,
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int feats_row) nogil:
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"""Add an entry to the knowledge base."""
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# This is what we'll map the orth to. It's where the entry will sit
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# in the vector of entries, so we can get it later.
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cdef int64_t index = self._entries.size()
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self._entries.push_back(
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_EntryC(
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vector_rows=vector_rows,
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feats_row=feats_row,
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prob=prob
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))
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self._index[key] = index
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return index |