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scripts/base/frameworks/measurement/plugins/std-dev.bro

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+@load ./sum
+@load ./variance
+
+module Metrics;
+
+export {
+	redef enum Calculation += { 
+		## Find the standard deviation of the values.
+		STD_DEV
+	};
+
+	redef record ResultVal += {
+		## For numeric data, this calculates the standard deviation.
+		std_dev:  double &log &optional;
+	};
+}
+
+# This depends on the variance plugin which uses priority -5
+hook add_to_calculation(filter: Filter, val: double, data: DataPoint, result: ResultVal) &priority=-10
+	{
+	if ( STD_DEV in filter$measure )
+		{
+		if ( result?$variance )
+			result$std_dev = sqrt(result$variance);
+		}
+	}
+
+hook plugin_merge_measurements(result: ResultVal, rv1: ResultVal, rv2: ResultVal) &priority=-10
+	{
+	if ( rv1?$sum || rv2?$sum )
+		{
+		result$sum = rv1?$sum ? rv1$sum : 0;
+		if ( rv2?$sum )
+			result$sum += rv2$sum;
+		}
+	}