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Posted to common-user@hadoop.apache.org by ykj <yk...@163.com> on 2009/05/20 09:15:54 UTC
how to change this code with hama
Hello,everyone
I am new to hama. in our project ,my team leader let me upgrade old
code, run it on hadoop with parallel matrix computation.this is old code:
public class EigenFaceGenerator {
Matrix averageFace; //stores the average face useful when probing
the database
Matrix eigVectors; //stores all the sorted eigen vectors from the
training set
Matrix eigValues; //Stores all the sorted eigen Values from the
training set
boolean trained = false; //has a training set been provided yet?
int numEigenVecs = 0; //number of eigen vectors availiable
/**
*
* @param faces array of pictures to be used for the training
* @param progress
*/
public void processTrainingSet(Face[] faces)
{
//TODO : there are errors that can be thrown when no fiels
are parsed into here
//TODO : Check that all the images are the same size
/**
* STEP 1
* Read in the images, flatten them out into one row of
values, and stack in a big matrix
*/
double[][] dpix = new
double[faces.length][faces[0].picture.getImagePixels().length];
for(int i=0; i<faces.length; i++)
{ //for each picture in the set
double[] pixels = faces[i].picture.getImagePixels();
for (int j=0; j<pixels.length; j++)
{
dpix[i][j] = pixels[j];
}
}
//make matrix of stacked flattened images
Matrix matrix = new Matrix(dpix);
/**
* STEP 2
* Calculate the average face, and then take this away from
each of the image
* effectivly calculating the difference form the average.
*/
//compute the average image
averageFace = new Matrix(1,matrix.getColumnDimension());
for(int i=0; i<matrix.getRowDimension(); i++)
{
averageFace.plusEquals(matrix.getMatrix(i,i,0,matrix.getColumnDimension() -
1));
}
averageFace.timesEquals(1.0/(double)matrix.getRowDimension()); //divide by
the number of pixels to get the average
Matrix bigAvg = new Matrix(matrix.getRowDimension(),
matrix.getColumnDimension());
for (int i=0; i<bigAvg.getRowDimension(); i++)
{
bigAvg.setMatrix(i,i,0,bigAvg.getColumnDimension()-1,averageFace);
}
// Compute the diference form the average face for each
image
Matrix A = matrix.minus(bigAvg).transpose();
/**
* STEP 3
* Now compute the the patternwise (nexamp x nexamp)
covariance matrix
*/
// TODO : for the presentation work out why this is done,
and what it's telling us
Matrix At = A.transpose();
Matrix L = At.times(A);
/**
* STEP 4
* Calculate the eigen values and vectors of this covariance
matrix
*
* % Get the eigenvectors (columns of Vectors) and
eigenvalues (diag of Values)
*/
EigenvalueDecomposition eigen = L.eig();
eigValues = eigen.getD();
eigVectors = eigen.getV();
/**
* STEP 5
* % Sort the vectors/values according to size of eigenvalue
*/
Matrix[] eigDVSorted = sortem(eigValues, eigVectors);
eigValues = eigDVSorted[0];
eigVectors = eigDVSorted[1];
/**
* STEP 6
* % Convert the eigenvectors of A'*A into eigenvectors of
A*A'
*/
eigVectors = A.times(eigVectors);
/**
* STEP 7
* % Get the eigenvalues out of the diagonal matrix and
* % normalize them so the evalues are specifically for
cov(A'), not A*A'.
*/
double[] values = diag(eigValues);
for(int i = 0; i < values.length; i++)
values[i] /= A.getColumnDimension() - 1;
/**
* STEP 8
* % Normalize Vectors to unit length, kill vectors corr. to
tiny evalues
*/
numEigenVecs = 0;
for(int i = 0; i < eigVectors.getColumnDimension(); i++) {
Matrix tmp;
if (values[i] < 0.0001)
{
tmp = new
Matrix(eigVectors.getRowDimension(),1);
}
else
{
tmp =
eigVectors.getMatrix(0,eigVectors.getRowDimension()-1,i,i).times(
1 / eigVectors.getMatrix(0,
eigVectors.getRowDimension() - 1, i, i).normF());
numEigenVecs++;
}
eigVectors.setMatrix(0,eigVectors.getRowDimension()-1,i,i,tmp);
//eigVectors.timesEquals(1 / eigVectors.getMatrix(0,
eigVectors.getRowDimension() - 1, i, i).normInf());
}
eigVectors =
eigVectors.getMatrix(0,eigVectors.getRowDimension() - 1, 0, numEigenVecs -
1);
trained = true;
/*System.out.println("There are " + numGood + "
eigenVectors\n\nEigenVectorSize");
System.out.println(eigVectors.getRowDimension());
System.out.println(eigVectors.getColumnDimension());
try {
PrintWriter pw = new PrintWriter("c:\\tmp\\test.txt");
eigVectors.print(pw, 8, 4);
pw.flush();
pw.close();
} catch (Exception e) {
e.printStackTrace();
}
int width = pics[0].img.getWidth(null);
BufferedImage biAvg =
imageFromMatrix(bigAvg.getArrayCopy()[0], width);
try {
saveImage(new File("c:\\tmp\\test.jpg"), biAvg);
} catch (IOException e1) {
e1.printStackTrace();
}*/
}
/**
* Returns a number of eigenFace values to be used in a feature
space
* @param pic
* @param number number of eigen feature values.
* @return will be of length number or this.getNumEigenVecs
whichever is the smaller
*/
public double[] getEigenFaces(Picture pic, int number)
{
if (number > numEigenVecs) //adjust the number to the maxium
number of eigen vectors availiable
number = numEigenVecs;
double[] ret = new double[number];
double[] pixels = pic.getImagePixels();
Matrix face = new Matrix(pixels, pixels.length);
Matrix Vecs =
eigVectors.getMatrix(0,eigVectors.getRowDimension()-1, 0,
number-1).transpose();
Matrix rslt = Vecs.times(face);
for (int i=0; i<number; i++)
{
ret[i] = rslt.get(i,0);
}
return ret;
}
/**
* Gets the diagonal of a matrix
* @param M matrix
* @return
*/
private double[] diag(Matrix M) {
double[] dvec = new double[M.getColumnDimension()];
for(int i = 0; i < M.getColumnDimension(); i++)
dvec[i] = M.get(i, i);
return dvec;
}
/**
* Sorts the Eigenvalues and vectors in decending order
*
* @param D = eigen Values
* @param V = eigen Vectors
* @return
*/
private Matrix[] sortem(Matrix D, Matrix V) {
//dvec = diag(D); // get diagonal components
double[] dvec = diag(D);
//NV = zeros(size(V));
//[dvec,index_dv] = sort(dvec); // sort dvec, maintain index in
index_dv
class di_pair{ double value; int index; };
di_pair[] dvec_indexed = new di_pair[dvec.length];
for(int i = 0; i < dvec_indexed.length; i++) {
dvec_indexed[i] = new di_pair();
dvec_indexed[i].index = i;
dvec_indexed[i].value = dvec[i];
}
Comparator di_pair_sort = new Comparator() {
public int compare(Object arg0, Object arg1) {
di_pair lt = (di_pair)arg0;
di_pair rt = (di_pair)arg1;
double dif = (lt.value - rt.value);
if(dif > 0) return -1;
if(dif < 0) return 1;
else return 0;
}
};
Arrays.sort(dvec_indexed, di_pair_sort);
//index_dv = flipud(index_dv);
//for i = 1:size(D,1)
// ND(i,i) = D(index_dv(i),index_dv(i));
// NV(:,i) = V(:,index_dv(i));
//end;
Matrix D2 = new Matrix(D.getRowDimension(),
D.getColumnDimension());
Matrix V2 = new Matrix(V.getRowDimension(),
V.getColumnDimension());
for(int i = 0; i < dvec_indexed.length; i++) {
D2.set(i, i, D.get(dvec_indexed[i].index,
dvec_indexed[i].index));
int height = V.getRowDimension() - 1;
Matrix tmp =
V.getMatrix(dvec_indexed[i].index,dvec_indexed[i].index,0,height);
V2.setMatrix(i, i,0,height, tmp);
}
//TODO : Not sure why, but this has to be flipped - check this
out maybe?
Matrix V3 = new Matrix(V.getRowDimension(),
V.getColumnDimension());
for (int i=0; i<V3.getRowDimension(); i++)
{
for (int j=0; j< V3.getColumnDimension(); j++)
{
V3.set(i,j,V2.get(V3.getRowDimension() - i - 1,
V3.getColumnDimension() - j - 1));
}
}
return new Matrix[] { D2, V3 };
}
public boolean isTrained() {
return trained;
}
public int getNumEigenVecs() {
return numEigenVecs;
}
}
I am not sure this code easily can be parallel computed,or how to change
this code to add the parallel compuation.any advice will be
appreciated.thanks in advance.
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