Spec
OpenAddressingQGramIndexA q-gram that uses open addressing hashing instead of an array.
A q-gram that uses open addressing hashing instead of an array.
| Extends | IndexQGram |
|---|---|
| All Extended | Index, IndexQGram |
| All Impl'd | StringTrieConcept |
| Defined in | <seqan/index.h> |
| Signature |
template <typename TIndex, typename TShapeSpec>
class Index<TText, IndexQGram<TShapeSpec, OpenAddressing> >;
|
Template Parameters
TText |
The text type. |
|---|---|
TShapeSpec |
The Shape specialization type. |
Member Function Overview
Member Functions Inherited From IndexQGram
Interface Function Overview
Interface Functions Inherited From Index
clearcountSequencesgetFibreindexCreateindexRawTextindexRequireindexSuppliedindexTextlengthopenrawtextAtsave
Interface Functions Inherited From IndexQGram
Interface Metafunction Overview
Interface Metafunctions Inherited From Index
Member Variable Overview
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double OpenAddressingQGramIndex::alphaLoad factor. Controls space/time-tradeoff and must be greater 1. Default value is 1.6.
Detailed Description
This index uses a non-trivial hashing for mapping q-gram hash values to buckets. This reduces the sizes of bucket directories (QGramDir, QGramCountsDir fibres) from Σq to min(α · n, \Sigmaq), for a load factor α > 1. A bucket still stores occurrences (or counts) of the same q-gram, but in contrast to the IndexQGram index, buckets are in random order due to the hashing.
Member Functions Detail
Index::Index();
Index::Index(index);
Index::Index(text[, shape]);
Constructor
Parameters
index
|
Other Index object to copy from. |
|---|---|
text
|
The text to be indexed. |
shape
|
The qgram Shape to be applied. |
Data Races
If not stated otherwise, concurrent invocation is not guaranteed to be thread-safe.
Member Variables Detail
double OpenAddressingQGramIndex::alpha
Load factor. Controls space/time-tradeoff and must be greater 1. Default value is 1.6.