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Extended Stats Aggregation
editExtended Stats Aggregation
editA multi-value
metrics aggregation that computes stats over numeric values extracted from the aggregated documents. These values can be extracted either from specific numeric fields in the documents, or be generated by a provided script.
The extended_stats
aggregations is an extended version of the stats
aggregation, where additional metrics are added such as sum_of_squares
, variance
and std_deviation
.
Assuming the data consists of documents representing exams grades (between 0 and 100) of students
{ "aggs" : { "grades_stats" : { "extended_stats" : { "field" : "grade" } } } }
The above aggregation computes the grades statistics over all documents. The aggregation type is extended_stats
and the field
setting defines the numeric field of the documents the stats will be computed on. The above will return the following:
{ ... "aggregations": { "grades_stats": { "count": 6, "min": 72, "max": 117.6, "avg": 94.2, "sum": 565.2, "sum_of_squares": 54551.51999999999, "variance": 218.2799999999976, "std_deviation": 14.774302013969987 } } }
The name of the aggregation (grades_stats
above) also serves as the key by which the aggreagtion result can be retrieved from the returned response.
Script
editComputing the grades stats based on a script:
{ ..., "aggs" : { "grades_stats" : { "extended_stats" : { "script" : "doc['grade'].value" } } } }
Value Script
editIt turned out that the exam was way above the level of the students and a grade correction needs to be applied. We can use value script to get the new stats:
{ "aggs" : { ... "aggs" : { "grades_stats" : { "extended_stats" : { "field" : "grade", "script" : "_value * correction", "params" : { "correction" : 1.2 } } } } } }