Can you share the code? sent from mobile On Nov 1, 2013 7:06 AM, "unmesha sreeveni" <[email protected]> wrote:
> > thanks Steve Loughran and Amr Shahin > Amr Shahin , i refered " > http://my.safaribooksonline.com/book/databases/hadoop/9780596521974/serialization/id3548156"; > the same thing only. but my toString is not returning anything. > > > > On Thu, Oct 31, 2013 at 5:57 PM, Amr Shahin <[email protected]> wrote: > >> Check this out: >> http://developer.yahoo.com/hadoop/tutorial/module5.html#writable-notes >> It shows how to create a customer writable. If you have "hadoop the >> definitive guide" there is a really good explanation about custom data >> types. >> >> Happy Halloween >> >> >> On Thu, Oct 31, 2013 at 3:03 PM, unmesha sreeveni <[email protected] >> >wrote: >> >> > this is my post from stackoverflow >> > but i am not getting any response. >> > >> > >> > I need to emit a 2D double array as key and value from mapper.There are >> > questions posted in stackoverflow. But they are not answered. >> > we have to create a custom datatype.but how?I am new to these custom >> > datatypes. i dnt have any idea where to start.I am doing some of the >> matrix >> > multiplication in a given dataset.and after that i need to emit the >> value >> > of >> > A*Atrns which will be a matrix and Atrans*D which will also be a >> matrix.so >> > how to emit these matrices from mapper.And the value should be >> > corresponding to the key itself.I think for that we need to use >> > WritableComparable. >> > >> > >> > >> > public class MatrixWritable implements >> WritableComparable<MatrixWritable>{ >> > >> > /** >> > * @param args >> > */ >> > private double[][] value; >> > >> > public MatrixWritable() { >> > // TODO Auto-generated constructor stub >> > set(new double[0][0]); >> > } >> > >> > public MatrixWritable(double[][] value) { >> > // TODO Auto-generated constructor stub >> > this.value = value; >> > } >> > >> > public void set(double[][] value) { >> > this.value = value; >> > } >> > >> > public double[][] getValue() { >> > return value; >> > } >> > >> > @Override >> > public void write(DataOutput out) throws IOException { >> > System.out.println("write"); >> > int row=0; >> > int col=0; >> > for(int i=0; i<value.length;i++){ >> > row = value.length; >> > for(int j=0; j<value[i].length; j++){ >> > col = value[i].length; >> > } >> > } >> > out.writeInt(row); >> > out.writeInt(col); >> > >> > System.out.println("\nTotal no of observations: "+row+":"+col); >> > >> > for(int i=0;i<row ; i++){ >> > for(int j= 0 ; j< col;j++){ >> > >> > out.writeDouble(value[i][j]); >> > } >> > } >> > //priting array >> > for(int vali =0;vali< value.length ;vali ++){ >> > for(int valj = 0;valj <value[0].length;valj++){ >> > System.out.print(value[vali][valj]+ "\t"); >> > } >> > System.out.println(""); >> > } >> > >> > } >> > >> > @Override >> > public void readFields(DataInput in) throws IOException { >> > int row = in.readInt(); >> > int col = in.readInt(); >> > >> > double[][] value = new double[row][col]; >> > for(int i=0;i<row ; i++){ >> > for(int j= 0 ; j< col;j++){ >> > value[i][j] = in.readDouble(); >> > >> > } >> > } >> > >> > } >> > >> > @Override >> > public int hashCode() { >> > >> > } >> > >> > @Override >> > public boolean equals(Object o) { >> > >> > } >> > >> > >> > @Override >> > public int compareTo(MatrixWritable o) { >> > // TODO Auto-generated method stub >> > return 0; >> > } >> > @Override >> > public String toString() { >> > >> > return Arrays.toString(value); >> > >> > } >> > >> > >> > >> > } >> > >> > I wrote matrix write,readfields and toString. >> > >> > 1.But my toString is not returning anything. why is it so? >> > >> > 2.How to print these values with in Reducer ?I tried doing(tried with >> > emiting only custom value- for checking) >> > >> > public class MyReducer extends >> > >> > >> > Reducer<MatrixWritable, MatrixWritable, IntWritable, Text> { >> > >> > public void reduce(Iterable<MatrixWritable> key, >> > Iterable<MatrixWritable> values, Context context){ >> > for(MatrixWritable c : values){ >> > >> > System.out.println("print value "+c.toString()); >> > >> > } >> > >> > } >> > >> > but Nothing is printing.when i tried to print value[0].length in >> toString() >> > method it showsArrayIndexOutOfBoundExcep.Am i doing any thing wrong.and >> i >> > also needed to print my data asmatrix so i tried >> > >> > public String toString() { >> > >> > String separator = ", "; >> > StringBuffer result = new StringBuffer(); >> > >> > // iterate over the first dimension >> > for (int i = 0; i < value.length; i++) { >> > // iterate over the second dimension >> > for(int j = 0; j < value[i].length; j++){ >> > result.append(value[i][j]); >> > System.out.print(value[i][j]); >> > result.append(separator); >> > } >> > // remove the last separator >> > result.setLength(result.length() - separator.length()); >> > // add a line break. >> > result.append("\n"); >> > } >> > >> > >> > return result.toString(); >> > >> > >> > } >> > >> > Again my output is empty. 3.Inorder to emit a key too as custom datatype >> > CompareTo is neccessary right . >> > >> > 4.so what should i include in that methods CompareTo,hashcode,equals and >> > what are these methods intended for. >> > Any Idea.Pls suggest a solution. >> > >> > -- >> > *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/ <http://www.amrita.edu/cyber/>* >
