@Override
public void map(Chunk[] chks) {
final Chunk y = importance ? chk_resp(chks) : null; // Response
final float[] rpred = importance ? new float[1 + _nclass] : null; // Row prediction
final double[] rowdata = importance ? new double[_ncols] : null; // Pre-allocated row data
final Chunk oobt = chk_oobt(chks); // Out-of-bag rows counter over all trees
// Iterate over all rows
for (int row = 0; row < oobt._len; row++) {
boolean wasOOBRow = false;
// For all tree (i.e., k-classes)
for (int k = 0; k < _nclass; k++) {
final DTree tree = _trees[k];
if (tree == null) continue; // Empty class is ignored
// If we have all constant responses, then we do not split even the
// root and the residuals should be zero.
if (tree.root() instanceof LeafNode) continue;
final Chunk nids = chk_nids(chks, k); // Node-ids for this tree/class
final Chunk ct = chk_tree(chks, k); // k-tree working column holding votes for given row
int nid = (int) nids.at80(row); // Get Node to decide from
// Update only out-of-bag rows
// This is out-of-bag row - but we would like to track on-the-fly prediction for the row
if (isOOBRow(nid)) { // The row should be OOB for all k-trees !!!
assert k == 0 || wasOOBRow
: "Something is wrong: k-class trees oob row computing is broken! All k-trees should agree on oob row!";
wasOOBRow = true;
nid = oob2Nid(nid);
if (tree.node(nid) instanceof UndecidedNode) // If we bottomed out the tree
nid = tree.node(nid).pid(); // Then take parent's decision
DecidedNode dn = tree.decided(nid); // Must have a decision point
if (dn._split.col() == -1) // Unable to decide?
dn = tree.decided(tree.node(nid).pid()); // Then take parent's decision
int leafnid = dn.ns(chks, row); // Decide down to a leafnode
// Setup Tree(i) - on the fly prediction of i-tree for row-th row
// - for classification: cumulative number of votes for this row
// - for regression: cumulative sum of prediction of each tree - has to be normalized
// by number of trees
double prediction =
((LeafNode) tree.node(leafnid)).pred(); // Prediction for this k-class and this row
if (importance)
rpred[1 + k] = (float) prediction; // for both regression and classification
ct.set0(row, (float) (ct.at0(row) + prediction));
// For this tree this row is out-of-bag - i.e., a tree voted for this row
oobt.set0(
row,
_nclass > 1
? 1
: oobt.at0(row)
+ 1); // for regression track number of trees, for classification boolean
// flag is enough
}
// reset help column for this row and this k-class
nids.set0(row, 0);
} /* end of k-trees iteration */
if (importance) {
if (wasOOBRow && !y.isNA0(row)) {
if (classification) {
int treePred = ModelUtils.getPrediction(rpred, data_row(chks, row, rowdata));
int actuPred = (int) y.at80(row);
if (treePred == actuPred) rightVotes++; // No miss !
} else { // regression
float treePred = rpred[1];
float actuPred = (float) y.at0(row);
sse += (actuPred - treePred) * (actuPred - treePred);
}
allRows++;
}
}
}
}
// --------------------------------------------------------------------------
// Build the next random k-trees represeint tid-th tree
private DTree[] buildNextKTrees(Frame fr, int mtrys, float sample_rate, Random rand, int tid) {
// We're going to build K (nclass) trees - each focused on correcting
// errors for a single class.
final DTree[] ktrees = new DTree[_nclass];
// Initial set of histograms. All trees; one leaf per tree (the root
// leaf); all columns
DHistogram hcs[][][] = new DHistogram[_nclass][1 /*just root leaf*/][_ncols];
// Use for all k-trees the same seed. NOTE: this is only to make a fair
// view for all k-trees
long rseed = rand.nextLong();
// Initially setup as-if an empty-split had just happened
for (int k = 0; k < _nclass; k++) {
assert (_distribution != null && classification)
|| (_distribution == null && !classification);
if (_distribution == null || _distribution[k] != 0) { // Ignore missing classes
// The Boolean Optimization
// This optimization assumes the 2nd tree of a 2-class system is the
// inverse of the first. This is false for DRF (and true for GBM) -
// DRF picks a random different set of columns for the 2nd tree.
// if( k==1 && _nclass==2 ) continue;
ktrees[k] = new DRFTree(fr, _ncols, (char) nbins, (char) _nclass, min_rows, mtrys, rseed);
boolean isBinom = classification;
new DRFUndecidedNode(
ktrees[k],
-1,
DHistogram.initialHist(fr, _ncols, nbins, hcs[k][0], isBinom)); // The "root" node
}
}
// Sample - mark the lines by putting 'OUT_OF_BAG' into nid(<klass>) vector
Timer t_1 = new Timer();
Sample ss[] = new Sample[_nclass];
for (int k = 0; k < _nclass; k++)
if (ktrees[k] != null)
ss[k] =
new Sample((DRFTree) ktrees[k], sample_rate)
.dfork(0, new Frame(vec_nids(fr, k), vec_resp(fr, k)), build_tree_one_node);
for (int k = 0; k < _nclass; k++) if (ss[k] != null) ss[k].getResult();
Log.debug(Sys.DRF__, "Sampling took: + " + t_1);
int[] leafs =
new int
[_nclass]; // Define a "working set" of leaf splits, from leafs[i] to tree._len for each
// tree i
// ----
// One Big Loop till the ktrees are of proper depth.
// Adds a layer to the trees each pass.
Timer t_2 = new Timer();
int depth = 0;
for (; depth < max_depth; depth++) {
if (!Job.isRunning(self())) return null;
hcs = buildLayer(fr, ktrees, leafs, hcs, true, build_tree_one_node);
// If we did not make any new splits, then the tree is split-to-death
if (hcs == null) break;
}
Log.debug(Sys.DRF__, "Tree build took: " + t_2);
// Each tree bottomed-out in a DecidedNode; go 1 more level and insert
// LeafNodes to hold predictions.
Timer t_3 = new Timer();
for (int k = 0; k < _nclass; k++) {
DTree tree = ktrees[k];
if (tree == null) continue;
int leaf = leafs[k] = tree.len();
for (int nid = 0; nid < leaf; nid++) {
if (tree.node(nid) instanceof DecidedNode) {
DecidedNode dn = tree.decided(nid);
for (int i = 0; i < dn._nids.length; i++) {
int cnid = dn._nids[i];
if (cnid == -1
|| // Bottomed out (predictors or responses known constant)
tree.node(cnid) instanceof UndecidedNode
|| // Or chopped off for depth
(tree.node(cnid) instanceof DecidedNode
&& // Or not possible to split
((DecidedNode) tree.node(cnid))._split.col() == -1)) {
LeafNode ln = new DRFLeafNode(tree, nid);
ln._pred = dn.pred(i); // Set prediction into the leaf
dn._nids[i] = ln.nid(); // Mark a leaf here
}
}
// Handle the trivial non-splitting tree
if (nid == 0 && dn._split.col() == -1) new DRFLeafNode(tree, -1, 0);
}
}
} // -- k-trees are done
Log.debug(Sys.DRF__, "Nodes propagation: " + t_3);
// ----
// Move rows into the final leaf rows
Timer t_4 = new Timer();
CollectPreds cp = new CollectPreds(ktrees, leafs).doAll(fr, build_tree_one_node);
if (importance) {
if (classification)
asVotes(_treeMeasuresOnOOB)
.append(cp.rightVotes, cp.allRows); // Track right votes over OOB rows for this tree
else /* regression */ asSSE(_treeMeasuresOnOOB).append(cp.sse, cp.allRows);
}
Log.debug(Sys.DRF__, "CollectPreds done: " + t_4);
// Collect leaves stats
for (int i = 0; i < ktrees.length; i++)
if (ktrees[i] != null) ktrees[i].leaves = ktrees[i].len() - leafs[i];
// DEBUG: Print the generated K trees
// printGenerateTrees(ktrees);
return ktrees;
}
