mirror of
https://github.com/laurent22/joplin.git
synced 2024-12-30 10:36:35 +02:00
38 lines
1.7 KiB
Markdown
38 lines
1.7 KiB
Markdown
|
# Search Engine
|
||
|
|
|
||
|
|
The Search Engine powers the Search input in the note list and the Goto Anything dialog.
|
||
|
|
|
||
|
|
## Search algorithm
|
||
|
|
|
||
|
|
### Discretely using only the most critical parameter in sorting
|
||
|
|
|
||
|
|
Sorting occurs as the Search Engine processes results, after searching for and weighting these results.
|
||
|
|
|
||
|
|
Parameters include fuzziness, title matching, weight (based on BM25 and age), the completed status of to-dos, and the note's age.
|
||
|
|
|
||
|
|
The Search Engine uses only the first relevant parameter to determine the order, rather than a weighted average.
|
||
|
|
In effect, this means search results with note title matches will appear above all results that only matched the note body,
|
||
|
|
regardless of weight or other parameters.
|
||
|
|
|
||
|
|
### Determining weight as a sorting parameter
|
||
|
|
|
||
|
|
The Search Engine determines the weight parameter using both [BM25](https://en.wikipedia.org/wiki/Okapi_BM25)
|
||
|
|
and the number of days since last user update.
|
||
|
|
|
||
|
|
#### BM25
|
||
|
|
|
||
|
|
The Search Engine determines BM25 based on "term frequency-inverse document frequency."
|
||
|
|
The "TF–IDF" value increases proportionally to the number of times a word appears in the document
|
||
|
|
and is offset by the number of documents in the corpus that contain the word, which helps to adjust
|
||
|
|
for the fact that some words appear more frequently in general.
|
||
|
|
|
||
|
|
BM25 returns weight zero for a search term that occurs in more than half the notes.
|
||
|
|
So terms that are abundant in all notes to have zero relevance w.r.t. BM25.
|
||
|
|
|
||
|
|
#### Days since last user update
|
||
|
|
|
||
|
|
Sorting increases the BM25 weight by the inverse number of days since the note was updated.
|
||
|
|
Recent notes will, therefore, be weighted highly in the search results.
|
||
|
|
This time-based weight decays logarithmically, becoming less of a factor than BM25 after months have passed.
|
||
|
|
|