zhipeng93 commented on code in PR #222:
URL: https://github.com/apache/flink-ml/pull/222#discussion_r1154216841
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flink-ml-lib/src/main/java/org/apache/flink/ml/feature/kbinsdiscretizer/KBinsDiscretizer.java:
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@@ -220,22 +220,46 @@ private static double[][]
findBinEdgesWithQuantileStrategy(
binEdges[columnId] =
new double[] {Double.NEGATIVE_INFINITY,
Double.POSITIVE_INFINITY};
} else {
- double width = 1.0 * features.length / numBins;
- double[] tempBinEdges = new double[numBins + 1];
+ double[] tempBinEdges;
+ if (features.length > numBins) {
+ double width = 1.0 * features.length / numBins;
+ tempBinEdges = new double[numBins + 1];
- for (int binEdgeId = 0; binEdgeId < numBins; binEdgeId++) {
- tempBinEdges[binEdgeId] = features[(int) (binEdgeId *
width)];
+ for (int binEdgeId = 0; binEdgeId < numBins; binEdgeId++) {
+ tempBinEdges[binEdgeId] = features[(int) (binEdgeId *
width)];
+ }
+ tempBinEdges[numBins] = features[numData - 1];
+ } else {
+ tempBinEdges = features;
}
- tempBinEdges[numBins] = features[numData - 1];
- // Removes bins that are empty, i.e., the left edge equals to
the right edge.
- Set<Double> edges = new HashSet<>(numBins);
+ // Bins with zero width should be converted to a non-empty bin.
+ Map<Double, Integer> edgesAndCnt = new HashMap<>(numBins);
for (double edge : tempBinEdges) {
+ edgesAndCnt.put(edge, edgesAndCnt.getOrDefault(edge, 0) +
1);
+ }
+ List<Double> edges = new ArrayList<>();
+ for (Map.Entry<Double, Integer> edgeAndCnt :
edgesAndCnt.entrySet()) {
+ double edge = edgeAndCnt.getKey();
+ int cnt = edgeAndCnt.getValue();
edges.add(edge);
+ if (cnt > 1) {
+ edges.add(edge);
+ }
+ }
+ tempBinEdges =
edges.stream().mapToDouble(Double::doubleValue).toArray();
+ Arrays.sort(tempBinEdges);
+ int i = 1;
+ for (; i < tempBinEdges.length - 1; i++) {
+ if (tempBinEdges[i] == tempBinEdges[i - 1]) {
+ tempBinEdges[i] = (tempBinEdges[i + 1] +
tempBinEdges[i - 1]) / 2;
+ }
+ }
+ if (tempBinEdges[i] == tempBinEdges[i - 1]) {
+ binEdges[columnId] = Arrays.copyOfRange(tempBinEdges, 0,
i);
Review Comment:
Good catch. I have updated the logic and also updated the java doc.
In the updated PR, [0, 1, 1] should be transformed into [0, 0.5, 1]
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