Mean - Amazon Glue
Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Mean

Checks whether the mean (average) of all the values in a column matches a given expression.

Syntax

Mean <COL_NAME> <EXPRESSION>

  • COL_NAME – The name of the column that you want to evaluate the data quality rule against.

    Supported column types: Byte, Decimal, Double, Float, Integer, Long, Short

  • EXPRESSION – An expression to run against the rule type response in order to produce a Boolean value. For more information, see Expressions.

Example: Average value

The following example rule checks whether the average of all of the values in a column exceeds a threshold.

Mean "Star_Rating" > 3
Mean "Salary" < 6200 where "Customer_ID < 10"

Sample dynamic rules

  • Mean "colA" > avg(last(10)) + std(last(2))

  • Mean "colA" between min(last(5)) - 1 and max(last(5)) + 1

Null behavior

The Mean rule will ignore rows with NULL values in the calculation of the mean. For example: 

+---+-----------+
|id |units      |
+---+-----------+
|100|0          |
|101|null       |
|102|20         |
|103|null       |
|104|40         |
+---+-----------+

The mean of column units will be (0 + 20 + 40) / 3 = 20. Rows 101 and 103 are not considered in this calculation.