# asterixdb-notifications mailing list archives

##### Site index · List index
Message view
Top
From "Taewoo Kim (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ASTERIXDB-1778) Calculating the edit-distance in SimilarityMetricEditDistance class can be improved.
Date Wed, 01 Feb 2017 05:36:52 GMT
```
[ https://issues.apache.org/jira/browse/ASTERIXDB-1778?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15848035#comment-15848035
]

Taewoo Kim commented on ASTERIXDB-1778:
---------------------------------------

I thought more and one or more conditions need to be applied. Let me get back to you once
I get the condition(s).

> Calculating the edit-distance in SimilarityMetricEditDistance class can be improved.
> ------------------------------------------------------------------------------------
>
>                 Key: ASTERIXDB-1778
>                 URL: https://issues.apache.org/jira/browse/ASTERIXDB-1778
>             Project: Apache AsterixDB
>          Issue Type: Improvement
>            Reporter: Taewoo Kim
>            Priority: Minor
>
> Local optimization of the current edit-distance handling code in AsterixDB: Can we terminate
the edit distance calculation based on a given edit-distance threshold T? I think the answer
is yes.
> Basic Algorithm:
> For two strings X and Y,
> Init:
> Construct D(len(X)+1=M, len(Y)+1=N).
> D(i,0) = i
> D(j,0) = j
> Iteration:
> For each i = 1 to M
>     For each j = 1 to N
>         D(i,j) = min( D(i-1,j) + 1 // deletion case
>                       D(i,j-1) + 1 // insertion case
>                       D(i-1,j-1) + cost (cost is 2 if X(i) != Y(j),
>                                                  cost is 0 if X(i) = Y(j))
>                     )
> Result:
> D(M,N) is the edit distance value.
> Example:
> Early Termination condition:
> So, for the given threshold T, we can stop the computation early if the values of three
cases are greater than T. That is,
> min (D(i-1,j), D(i,j-1), D(i-1,j-1)) > T
> This holds since if the cost of all possible cases (insertion, deletion, and substitution)
is greater than T, all future operations will be greater than T in any cases.

--
This message was sent by Atlassian JIRA
(v6.3.15#6346)

```
Mime
View raw message