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Posted to dev@mahout.apache.org by "Dmitriy Lyubimov (JIRA)" <ji...@apache.org> on 2013/07/30 00:37:50 UTC
[jira] [Created] (MAHOUT-1298) SparseRowMatrix,SparseColMatrix:
optimize transpose()
Dmitriy Lyubimov created MAHOUT-1298:
----------------------------------------
Summary: SparseRowMatrix,SparseColMatrix: optimize transpose()
Key: MAHOUT-1298
URL: https://issues.apache.org/jira/browse/MAHOUT-1298
Project: Mahout
Issue Type: New Feature
Components: Math
Affects Versions: 0.8
Reporter: Dmitriy Lyubimov
Assignee: Dmitriy Lyubimov
Fix For: 0.9
these matrices lack optimized transpose and rely onto AbstractMatrix's O(mn) implementation which is not cool for very sparse subblocks.
proposal is to implement a custom transpose with two things in mind:
1) transpose result to row sparse matrix should be col sparse matrix, and vice versa (and not from default like() as default implementation would take);
2) obviously, iterate only thru non-zero elements only of all rows(columns).
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Re: [jira] [Created] (MAHOUT-1298) SparseRowMatrix,SparseColMatrix:
optimize transpose()
Posted by Peng Cheng <pc...@uowmail.edu.au>.
+1, we have type conversion anyway.
On 29/07/2013 6:40 PM, Sebastian Schelter wrote:
> +1
>
> 2013/7/29 Dmitriy Lyubimov (JIRA) <ji...@apache.org>
>
>> Dmitriy Lyubimov created MAHOUT-1298:
>> ----------------------------------------
>>
>> Summary: SparseRowMatrix,SparseColMatrix: optimize transpose()
>> Key: MAHOUT-1298
>> URL: https://issues.apache.org/jira/browse/MAHOUT-1298
>> Project: Mahout
>> Issue Type: New Feature
>> Components: Math
>> Affects Versions: 0.8
>> Reporter: Dmitriy Lyubimov
>> Assignee: Dmitriy Lyubimov
>> Fix For: 0.9
>>
>>
>> these matrices lack optimized transpose and rely onto AbstractMatrix's
>> O(mn) implementation which is not cool for very sparse subblocks.
>>
>> proposal is to implement a custom transpose with two things in mind:
>>
>> 1) transpose result to row sparse matrix should be col sparse matrix, and
>> vice versa (and not from default like() as default implementation would
>> take);
>>
>> 2) obviously, iterate only thru non-zero elements only of all
>> rows(columns).
>>
>> --
>> This message is automatically generated by JIRA.
>> If you think it was sent incorrectly, please contact your JIRA
>> administrators
>> For more information on JIRA, see: http://www.atlassian.com/software/jira
>>
Re: [jira] [Created] (MAHOUT-1298) SparseRowMatrix,SparseColMatrix:
optimize transpose()
Posted by Sebastian Schelter <ss...@apache.org>.
+1
2013/7/29 Dmitriy Lyubimov (JIRA) <ji...@apache.org>
> Dmitriy Lyubimov created MAHOUT-1298:
> ----------------------------------------
>
> Summary: SparseRowMatrix,SparseColMatrix: optimize transpose()
> Key: MAHOUT-1298
> URL: https://issues.apache.org/jira/browse/MAHOUT-1298
> Project: Mahout
> Issue Type: New Feature
> Components: Math
> Affects Versions: 0.8
> Reporter: Dmitriy Lyubimov
> Assignee: Dmitriy Lyubimov
> Fix For: 0.9
>
>
> these matrices lack optimized transpose and rely onto AbstractMatrix's
> O(mn) implementation which is not cool for very sparse subblocks.
>
> proposal is to implement a custom transpose with two things in mind:
>
> 1) transpose result to row sparse matrix should be col sparse matrix, and
> vice versa (and not from default like() as default implementation would
> take);
>
> 2) obviously, iterate only thru non-zero elements only of all
> rows(columns).
>
> --
> This message is automatically generated by JIRA.
> If you think it was sent incorrectly, please contact your JIRA
> administrators
> For more information on JIRA, see: http://www.atlassian.com/software/jira
>