The current 1.4 docs mention that the scripted_metric aggregation is experimental, and to share our usages. I've found a really great use on our project so I thought I'd share!
While the 'stats' metric provides great data like 'sum' and 'average', we needed to calculate a weighted average. In this case, the weighting field is 'principal_amount', and the field we'd like the metric on is 'rate'. A CURL for this agg is here: curl -XGET "http://localhost:9200/my_index/_search"; -d' { "size": 0, "aggs": { "test_script": { "scripted_metric": { "init_script": "_agg[\"numerator\"] = []; _agg[\"denominator\"] = [];", "map_script": "_agg.numerator << (doc[\"principal_amount\"].value * doc[\"rate\"].value); _agg.denominator << doc[\"principal_amount\"].value", "combine_script" : "num_sum = 0; den_sum = 0; for (t in _agg.numerator) { num_sum += t }; for (t in _agg.denominator) { den_sum += t };return [num_sum: num_sum, den_sum: den_sum]", "reduce_script" : "num_sum = 0; den_sum=0; for (a in _aggs) { num_sum += a.num_sum; den_sum += a.den_sum; }; return num_sum/den_sum" } } } }' For reference, a weighted average is defined here (it's pretty simple): http://www.investopedia.com/terms/w/weightedaverage.asp Without this great new aggregation type, I guess I'd have to index the product of 'rate' and 'principal_amount' so that I could run a stats agg on that. It would work, but not as clean. One thing I notice here is that there is quite a bit of redundancy between the 'combine' and 'reduce' scripts. I haven't fully explored what the most concise representation might look like, but it could be something to think about as this aggregation develops. Thanks for including it! -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to elasticsearch+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/elasticsearch/8dd58a43-df8e-4c7a-9c88-a9ac33055fc4%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
