std
Gets a field name for a $group operation representing the sample standard deviation of the values of the given expression when applied to all members of the group.
Use if the values encompass a sample of a population of data from which to generalize about the population.
Return
the field @mongodb.driver.manual reference/operator/aggregation/stdDevSamp/ $stdDevSamp @mongodb.server.release 3.2
Parameters
property
the data class property
expression
the expression