Double.NEGATIVE_INFINITY.Double.POSITIVE_INFINITYRanking based on the natural ordering on doubles.
+ *NaNs are treated according to the configured {@link NaNStrategy} and ties + * are handled using the selected {@link TiesStrategy}. + * Configuration settings are supplied in optional constructor arguments. + * Defaults are {@link NaNStrategy#MAXIMAL} and {@link TiesStrategy#AVERAGE}, + * respectively. When using {@link TiesStrategy#RANDOM}, a + * {@link RandomGenerator} may be supplied as a constructor argument.
+ *Examples: + *
| + * Input data: (20, 17, 30, 42.3, 17, 50, Double.NaN, Double.NEGATIVE_INFINITY, 17) + * | ||
|---|---|---|
| NaNStrategy | TiesStrategy | + *rank(data) |
+ *
| default (NaNs maximal) | + *default (ties averaged) | + *(5, 3, 6, 7, 3, 8, 9, 1, 3) |
| default (NaNs maximal) | + *MINIMUM | + *(5, 2, 6, 7, 2, 8, 9, 1, 2) |
| MINIMAL | + *default (ties averaged) | + *(6, 4, 7, 8, 4, 9, 1.5, 1.5, 4) |
| REMOVED | + *SEQUENTIAL | + *(5, 2, 6, 7, 3, 8, 1, 4) |
| MINIMAL | + *MAXIMUM | + *(6, 5, 7, 8, 5, 9, 2, 2, 5) |
data using the natural ordering on Doubles, with
+ * NaN values handled according to nanStrategy and ties
+ * resolved using tiesStrategy.
+ *
+ * @param data array to be ranked
+ * @return array of ranks
+ */
+ public double[] rank(double[] data) {
+
+ // Array recording initial positions of data to be ranked
+ IntDoublePair[] ranks = new IntDoublePair[data.length];
+ for (int i = 0; i < data.length; i++) {
+ ranks[i] = new IntDoublePair(data[i], i);
+ }
+
+ // Recode, remove or record positions of NaNs
+ Listranks.
+ *
+ * @param ranks array to be searched for NaNs
+ * @return true iff ranks contains one or more NaNs
+ */
+ private boolean containsNaNs(IntDoublePair[] ranks) {
+ for (int i = 0; i < ranks.length; i++) {
+ if (Double.isNaN(ranks[i].getValue())) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ /**
+ * Resolve a sequence of ties, using the cconfigured {@link TiesStrategy}.
+ * The input ranks array is expected to take the same value
+ * for all indices in tiesTrace. The common value is recoded
+ * according to the tiesStrategy. For example, if ranks = <5,8,2,6,2,7,1,2>,
+ * tiesTrace = <2,4,7> and tiesStrategy is MINIMUM, ranks will be unchanged.
+ * The same array and trace with tiesStrategy AVERAGE will come out
+ * <5,8,3,6,3,7,1,3>.
+ *
+ * @param ranks array of ranks
+ * @param tiesTrace list of indices where ranks is constant
+ * -- that is, for any i and j in TiesTrace, ranks[i] == ranks[j]
+ *
+ */
+ private void resolveTie(double[] ranks, Listdata[i] = value for each i in tiesTrace.
+ *
+ * @param data array to modify
+ * @param tiesTrace list of index values to set
+ * @param value value to set
+ */
+ private void fill(double[] data, Listranks[i] = Double.NaN for each i in nanPositions.
+ *
+ * @param ranks array to modify
+ * @param nanPositions list of index values to set to Double.NaN
+ */
+ private void restoreNaNs(double[] ranks, Listranks is NaN.
+ *
+ * @param ranks array to search for NaNs
+ * @return list of indexes i such that ranks[i] = NaN
+ */
+ private ListDouble.compare(value, other.value)
+ */
+ public int compareTo(IntDoublePair other) {
+ return Double.compare(value, other.value);
+ }
+
+ /**
+ * Returns the value of the pair.
+ * @return value
+ */
+ public double getValue() {
+ return value;
+ }
+
+ /**
+ * Returns the original position of the pair.
+ * @return position
+ */
+ public int getPosition() {
+ return position;
+ }
+ }
+}
diff --git a/src/java/org/apache/commons/math/stat/ranking/RankingAlgorithm.java b/src/java/org/apache/commons/math/stat/ranking/RankingAlgorithm.java
new file mode 100644
index 000000000..e0cee28c4
--- /dev/null
+++ b/src/java/org/apache/commons/math/stat/ranking/RankingAlgorithm.java
@@ -0,0 +1,41 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.commons.math.stat.ranking;
+
+/**
+ * Interface representing a rank transformation.
+ *
+ * @since 2.0
+ * @version $Revision:$ $Date:$
+ */
+public interface RankingAlgorithm {
+ /**
+ * Performs a rank transformation on the input data, returning an array + * of ranks.
+ * + *Ranks should be 1-based - that is, the smallest value + * returned in an array of ranks should be greater than or equal to one, + * rather than 0. Ranks should in general take integer values, though + * implementations may return averages or other floating point values + * to resolve ties in the input data.
+ * + * @param data array of data to be ranked + * @return an array of ranks corresponding to the elements of the input array + */ + double[] rank (double[] data); +} diff --git a/src/java/org/apache/commons/math/stat/ranking/TiesStrategy.java b/src/java/org/apache/commons/math/stat/ranking/TiesStrategy.java new file mode 100644 index 000000000..2c2cbf355 --- /dev/null +++ b/src/java/org/apache/commons/math/stat/ranking/TiesStrategy.java @@ -0,0 +1,55 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.commons.math.stat.ranking; + +/** + * Strategies for handling tied values in rank transformations. + *