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https://issues.apache.org/jira/browse/MAHOUT-1193?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13635670#comment-13635670
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Gokhan Capan commented on MAHOUT-1193:
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Is it just me or doesn't it compile because it does not have super-matching
constructor and cardinality is not declared?
What I understand from the implementation is that we create a Map<Integer,
Matrix>, each Entry of which represents a block and the associated DenseMatrix.
If I didn't totally misunderstand the implementation, if the blockSize always
will be 1, this associates a matrix with each row.
Say I want to sacrifice some memory and try to set blockSize to 5, so if there
were n actual rows in [row/blockSize, row/blockSize+5), there would be 5-n
empty ones, and I am OK with that. Shouldn't we modify the extendToThisRow
method such that:
int blockIndex = row / blockSize;
Matrix block = data.get(blockIndex);
if (block == null) {
data.put(blockIndex, new DenseMatrix(blockSize, columns));
} else if (!block.hasRow(row)) {
block.assignRow(row % blockIndex, new DenseVector(columns))
}
rows = Math.max(row + 1, rows);
cardinality[ROW] = rows;
> We may want a BlockSparseMatrix
> -------------------------------
>
> Key: MAHOUT-1193
> URL: https://issues.apache.org/jira/browse/MAHOUT-1193
> Project: Mahout
> Issue Type: Bug
> Reporter: Ted Dunning
> Attachments: MAHOUT-1193.patch
>
>
> Here is an implementation.
> Is it good enough to commit?
> Is it useful?
> Is it redundant?
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