On Friday 30 September 2011 04:17 PM, Rajen Bhatt (RBEI/EST1) wrote:
Dear Experts:
We are scaling down an image to few partitions and processing each
partition in the MAP class. We want to save the output of MAP class
only to demonstrate and present how this output sub images are looking
like. Can somebody give us a hint on how to only save the output of
MAP class (before we send them to the REDUCER class) ? We want to
demonstrate to the students the process of MAP REDUCE flow on simple
image processing operation. We are doing the attached images operation
using MAP REDUCE. We are sending the original image and getting as an
output the edge detected image. First one is the input Image, we are
splitting it, performing the edge detection on each split, and then
merging in the reducer.
Thanks and Regards,
~~
*Dr. Rajen Bhatt *
*(*/*Corporate Research*/**/*@ Robert Bosch, India*/*)*
Off: +91-80-4191-2025
Mob: +91-9901241005
I have the following approach
At the reducer side, first write the map output to a file and then
perform the reduce logic. After completion of the reduce logic again
write the output to another file. Something like below
reduce(key,value, context) {
mo.write(key,value,namedoutputfile1)
reduce Logic
mo.write(key,value after reduce logic, namedoutputfile2)
}
mo : an instance of Multiple Outputs
So here, namedoutputfile1 has mapper output and nameoutputfile2 has
reducer output.
PS: The above approach works only when there is only one mapper from
which reducer gets its input.
--
/Thanks&Regards,/
/Bh.V.S.Kamesh/
