Reference Entry
Avg Aggregation
Discovery · advanced · order 25
Compute the arithmetic mean of indexed numeric or date values, optionally within the current result set.
Relevant APIs
Avg Aggregation
avg() returns the arithmetic mean of the indexed values in a numeric or date field.
Basic usage
const wordCountIndex = index.getFieldIndex("wordCount") as NumericFieldIndex;
const averageLength = wordCountIndex.avg();
How it works
avg() is based on values, not documents.
That means a multi-valued document contributes all of its values to the average.
If there are no values, avg() returns null.
const averageLengthInSubset = wordCountIndex.avg(new Set(["a", "b"]));
When to use it
- average article length
- average score or popularity
- average timestamp in a synthetic or event-style dataset
Tradeoffs
- If you need the full summary,
stats()is usually more convenient.