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From Jeff Eastman <>
Subject Re: Clustering from DB
Date Fri, 10 Jul 2009 21:45:56 GMT
It does appear that recent changes have broken KMeans. Removing the "/*" 
makes the example work but won't work in general if there is more than 
one reducer specified. For that, the "part-0000" in the calling location 
needs to be removed so that isConverged() can iterate over all of the 
cluster part files produced by the reducers. The unit test 
'testKMeansMRJob' throws the same exception, but something must be 
handling that exception because the test passes for some reason.

I will have some time to look into this in a day or so but in the mean 
time perhaps the folks who have been doing all the KMeans changes can 
figure it out.


nfantone wrote:
> This error is still bugging me. The exception:
> output/clusters-0/part-00000/* does not exist.
> File output/clusters-0/part-00000/*
> does not exist.
> ocurrs first at:
> org.apache.mahout.clustering.kmeans.KMeansDriver.isConverged(
> which corresponds to:
>   private static boolean isConverged(String filePath, JobConf conf,
> FileSystem fs)
>       throws IOException {
>     Path outPart = new Path(filePath + "/*");
>     SequenceFile.Reader reader = new SequenceFile.Reader(fs, outPart,
> conf);  <-- THIS
>     ...
>   }
> where isConverged() is called in this fashion:
> return isConverged(clustersOut + "/part-00000", conf, fs);
> by runIteration(), which is previously invoked by runJob() like:
>      String clustersOut = output + "/clusters-" + iteration;
>       converged = runIteration(input, clustersIn, clustersOut, measureClass,
>           delta, numReduceTasks, iteration);
> Consequently, assuming its the first iteration and the output folder
> has been named "output" by the user, the SequenceFile.Reader receives
> "output/clusters-0/part-00000/*" as a path, which is non-existent. I
> believe the path should end in "part-00000" and the  + "/*" should be
> removed... although someone, evidently, thought otherwise.
> Any feedback?
> On Mon, Jul 6, 2009 at 5:39 PM, nfantone<> wrote:
>> I was using Canopy to create input clusters, but the error appeared
>> while running kMeans (if I run kMeans' job only with previously
>> created clusters from Canopy placed in output/canopies as initial
>> clusters, it still fails). I noticed no other problems. I was using
>> revision 790979 before updating.  Strangely, there were no changes in
>> the job and drivers class from that revision. svn diff shows that the
>> only classes that changed in org.apache.mahout.clustering.kmeans
>> package were and
>> On Mon, Jul 6, 2009 at 3:55 PM, Jeff Eastman<> wrote:
>>> Hum, no, it's looking for the output of the first iteration. Were there
>>> other errors? What was the last revision you were running? It does look like
>>> something got horked, as it should be looking for output/clusters-0/*. Can
>>> you diff the job and driver class to see what changed?
>>> Jeff
>>> nfantone wrote:
>>>> Fellows, today I updated to revision 791558 and while running kMeans I
>>>> got the following exception:
>>>> WARNING: File
>>>> output/clusters-0/part-00000/* does not exist.
>>>> File output/clusters-0/part-00000/*
>>>> does not exist.
>>>> The algorithm isn't interrupted, though. But this exception wasn't
>>>> thrown before the update and, to me, its message is not quite clear.
>>>> It seems as it's looking for any file inside a "part-00000" directory,
>>>> which doesn't exist; and, as far as I know, "part-xxxxx" are default
>>>> names for output files.
>>>> I could show the entire stack trace, if needed. Any pointers?
>>>> On Thu, Jul 2, 2009 at 3:16 PM, nfantone<> wrote:
>>>>> Thanks for the feedback, Jeff.
>>>>>> The logical format of input to KMeans is <Key, Vector> as it
is in
>>>>>> sequence
>>>>>> file format, but the Key is never used. To my knowledge, there is
>>>>>> requirement to assign identifiers to the input points*. Users are
>>>>>> to
>>>>>> associate an arbitrary name field with each vector - also label mappings
>>>>>> may
>>>>>> be assigned - but these are not manipulated by KMeans or any of the
>>>>>> other
>>>>>> clustering applications. The name field is now used as a vector
>>>>>> identifier
>>>>>> by the KMeansClusterMapper - if it is non-null - in the output step
>>>>>> only.
>>>>> The key may not be used internally, but externally they can prove to
>>>>> be pretty useful. For me, keys are userIDs and each Vector represents
>>>>> his/her historical behavior. Being able to collect the output
>>>>> information as <UserID, ClusterID> is quite neat as it allows me
>>>>> for instance, retrieve user information using data directly from a
>>>>> HDFS file's field.

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