Mahout Version: 0.6-SNAPSHOT from trunk
I convert my vectors (generated by seq2sparse) to matrix using the RowIdJob.

RowIdJob creates a matrix (IntWritable, VectorWritable) and a docIndex (IntWritable, Text).
I am now trying to dump the matrix generated using MatrixDumper and I see this error:-

Exception in thread "main" java.lang.ClassCastException: org.apache.mahout.math.VectorWritable cannot be cast to org.apache.mahout.math.MatrixWritable
    at org.apache.mahout.utils.MatrixDumper.exportCSV(MatrixDumper.java:70)
    at org.apache.mahout.utils.MatrixDumper.run(MatrixDumper.java:63)
    at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
    at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79)
    at org.apache.mahout.utils.MatrixDumper.main(MatrixDumper.java:50)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:68)
    at org.apache.hadoop.util.ProgramDriver.driver(ProgramDriver.java:139)
    at org.apache.mahout.driver.MahoutDriver.main(MahoutDriver.java:188)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:156)
Obviously the MatrixDumper is expecting to retrieve a MatrixWritable, but what's being written into the matrix is a VectorWritable.

Am I using MatrixDumper the right way or do we have an issue here?

Dumping vectors is a separate job called 'vectordump'.

On Fri, Jan 20, 2012 at 1:54 PM, Suneel Marthi <[EMAIL PROTECTED]> wrote:
> Mahout Version: 0.6-SNAPSHOT from trunk
>
>
> I convert my vectors (generated by seq2sparse) to matrix using the RowIdJob.
>
> RowIdJob creates a matrix (IntWritable, VectorWritable) and a docIndex (IntWritable, Text).
>
>
> I am now trying to dump the matrix generated using MatrixDumper and I see this error:-
>
> Exception in thread "main" java.lang.ClassCastException: org.apache.mahout.math.VectorWritable cannot be cast to org.apache.mahout.math.MatrixWritable
>     at org.apache.mahout.utils.MatrixDumper.exportCSV(MatrixDumper.java:70)
>     at org.apache.mahout.utils.MatrixDumper.run(MatrixDumper.java:63)
>     at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
>     at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79)
>     at org.apache.mahout.utils.MatrixDumper.main(MatrixDumper.java:50)
>     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
>     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>     at java.lang.reflect.Method.invoke(Method.java:597)
>     at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:68)
>     at org.apache.hadoop.util.ProgramDriver.driver(ProgramDriver.java:139)
>     at org.apache.mahout.driver.MahoutDriver.main(MahoutDriver.java:188)
>     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
>     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>     at java.lang.reflect.Method.invoke(Method.java:597)
>     at org.apache.hadoop.util.RunJar.main(RunJar.java:156)
>
>
> Obviously the MatrixDumper is expecting to retrieve a MatrixWritable, but what's being written into the matrix is a VectorWritable.
>
> Am I using MatrixDumper the right way or do we have an issue here?

--
Lance Norskog
[EMAIL PROTECTED]