m-trieu commented on code in PR #29445:
URL: https://github.com/apache/beam/pull/29445#discussion_r1394868437
##########
sdks/java/core/src/main/java/org/apache/beam/sdk/util/HistogramData.java:
##########
@@ -184,6 +193,26 @@ public synchronized void record(double value) {
buckets[bucketType.getBucketIndex(value)]++;
numBoundedBucketRecords++;
}
+ updateStatistics(value);
+ }
+
+ /**
+ * Update 'mean' and 'sum of squared deviations' statistics with the newly
recorded value <a
+ *
href="https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Welford's_online_algorithm">
+ * Welford Method</a>.
+ *
+ * @param value
+ */
+ private void updateStatistics(double value) {
+ long count = getTotalCount();
+ if (count == 1) {
+ mean = value;
+ return;
+ }
+
+ double old_mean = mean;
+ mean = old_mean + (value - old_mean) / count;
+ sum_of_squared_deviations += (value - mean) * (value - old_mean);
Review Comment:
for java, camel case is preferred
https://google.github.io/styleguide/javaguide.html#s5.3-camel-case
##########
sdks/java/core/src/main/java/org/apache/beam/sdk/util/HistogramData.java:
##########
@@ -184,6 +193,26 @@ public synchronized void record(double value) {
buckets[bucketType.getBucketIndex(value)]++;
numBoundedBucketRecords++;
}
+ updateStatistics(value);
+ }
+
+ /**
+ * Update 'mean' and 'sum of squared deviations' statistics with the newly
recorded value <a
+ *
href="https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Welford's_online_algorithm">
+ * Welford Method</a>.
+ *
+ * @param value
+ */
+ private void updateStatistics(double value) {
+ long count = getTotalCount();
+ if (count == 1) {
+ mean = value;
+ return;
+ }
+
+ double old_mean = mean;
Review Comment:
for java, camel case is preferred
https://google.github.io/styleguide/javaguide.html#s5.3-camel-case
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