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Use a TreeSet instead of an ArrayList when dropping columns after phase 1 of the simplex solver to improve performance. 

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1367227 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Thomas Neidhart 2012-07-30 19:07:05 +00:00
parent ebc0d3d309
commit 107d7f3ea8
1 changed files with 15 additions and 12 deletions
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27
src/main/java/org/apache/commons/math3/optimization/linear/SimplexTableau.java
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@ -26,6 +26,7 @@ import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;
import org.apache.commons.math3.linear.Array2DRowRealMatrix;
import org.apache.commons.math3.linear.MatrixUtils;
@ -333,7 +334,7 @@ class SimplexTableau implements Serializable {
return;
}
List<Integer> columnsToDrop = new ArrayList<Integer>();
Set<Integer> columnsToDrop = new TreeSet<Integer>();
columnsToDrop.add(0);
// positive cost non-artificial variables
@ -346,24 +347,26 @@ class SimplexTableau implements Serializable {
// non-basic artificial variables
for (int i = 0; i < getNumArtificialVariables(); i++) {
int col = i + getArtificialVariableOffset();
if (getBasicRow(col) == null) {
columnsToDrop.add(col);
}
int col = i + getArtificialVariableOffset();
if (getBasicRow(col) == null) {
columnsToDrop.add(col);
}
}
double[][] matrix = new double[getHeight() - 1][getWidth() - columnsToDrop.size()];
for (int i = 1; i < getHeight(); i++) {
int col = 0;
for (int j = 0; j < getWidth(); j++) {
if (!columnsToDrop.contains(j)) {
matrix[i - 1][col++] = tableau.getEntry(i, j);
int col = 0;
for (int j = 0; j < getWidth(); j++) {
if (!columnsToDrop.contains(j)) {
matrix[i - 1][col++] = tableau.getEntry(i, j);
}
}
}
}
for (int i = columnsToDrop.size() - 1; i >= 0; i--) {
columnLabels.remove((int) columnsToDrop.get(i));
// remove the columns in reverse order so the indices are correct
Integer[] drop = columnsToDrop.toArray(new Integer[columnsToDrop.size()]);
for (int i = drop.length - 1; i >= 0; i--) {
columnLabels.remove((int) drop[i]);
}
this.tableau = new Array2DRowRealMatrix(matrix);