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
clear
countSequences
getFibre
indexCreate
indexRawText
indexRequire
indexSupplied
indexText
length
open
rawtextAt
save
Interface Functions Inherited From IndexQGram
Interface Metafunction Overview
Interface Metafunctions Inherited From Index
Member Variable Overview
-
double OpenAddressingQGramIndex::alpha
Load 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.