http://mapreduce-tutorial.blogspot.in/2011/04/custom-data-types.html I have gone through this link.What i understood is for emitting two 2D double arrays as key and value from mapper and read those two arrays as key and value from reducer ..i need to create a class which implements a writable ... am i right?
And how to override those methods in writable. These r all new to me. But i am picking up. On Mon, Oct 28, 2013 at 8:52 PM, unmesha sreeveni <[email protected]>wrote: > thanx for ur replies Mirko Kämpf and bertrand. i hv read in many of the > document for the creation of custom datatypes. i have nt tried with > advanced datatypes.I will Try and see. > > Before tat...this wont fulfill my need right??? > > *public static class DoubleArrayWritable extends TwoDArrayWritable { > public DoubleArrayWritable() { > super(DoubleWritable.class); > } > } > * > > * DoubleArrayWritable EArray = new DoubleArrayWritable(); > DoubleWritable[][] Edata = new DoubleWritable[Erow][Ecol]; > for (int k = 0; k < Erow; k++) { > for(int j=0;j< Ecol;j++){ > Edata[k][j] = new DoubleWritable(E[k][j]); > } > } > EArray.set(Edata); > > DoubleArrayWritable EDArray = new DoubleArrayWritable(); > DoubleWritable[][] EDdata = new > DoubleWritable[EtransDerow][EtransDecol]; > for (int k1 = 0; k1 < EtransDerow; k1++) { > for(int j1=0;j1< EtransDecol;j1++){ > EDdata[k1][j1] = new DoubleWritable(ED[k1][j1]); > > } > } > EDArray.set(EDdata);*** > > *context**.write(EArray, EDArray);* > > > The 2D array i need to emit is Edata and EDArray.I am changing the double > array to *DoubleArrayWritable * > ,but y this dont work? > > > > > > > > On Mon, Oct 28, 2013 at 5:22 PM, Bertrand Dechoux <[email protected]>wrote: > >> Use @Override to specify that you indeed override the good methods. >> >> Bertrand >> >> >> On Mon, Oct 28, 2013 at 11:30 AM, Mirko Kämpf <[email protected]>wrote: >> >>> Hi, >>> >>> you should create a custom data type, which contains two of the >>> DoubleArrayWritable instances. This custom data type idea is also >>> explained here: >>> http://my.safaribooksonline.com/book/-/9781849517287/4dot-developing-complex-hadoop-mapreduce-applications/ch04s03_html >>> >>> Good luck. >>> Mirko >>> >>> >>> >>> 2013/10/28 unmesha sreeveni <[email protected]> >>> >>>> >>>> http://stackoverflow.com/questions/19602692/java-lang-classcastexception-in-hadoop-mapreduce >>>> >>>> I tried out, but it is not working. >>>> >>>> I was able to emit 1 2D array..but When i cross checked once more, i am >>>> not able to print the matrix(2D array) in reducer. >>>> >>>> Can anyone suggest me a gud way to emit 2 Matrices from mapper. >>>> >>>> >>>> >>>> -- >>>> *Thanks & Regards* >>>> * >>>> * >>>> Unmesha Sreeveni U.B* >>>> * >>>> *Junior Developer >>>> * >>>> *Amrita Center For Cyber Security >>>> * >>>> * >>>> Amritapuri. >>>> >>>> www.amrita.edu/cyber/ >>>> * >>>> >>> >>> >> >> >> -- >> Bertrand Dechoux >> > > > > -- > *Thanks & Regards* > * > * > Unmesha Sreeveni U.B* > * > *Junior Developer > * > *Amrita Center For Cyber Security > * > * > Amritapuri. > > www.amrita.edu/cyber/ > * > -- *Thanks & Regards* * * Unmesha Sreeveni U.B* * *Junior Developer * *Amrita Center For Cyber Security * * Amritapuri. www.amrita.edu/cyber/ *
