Function stddev() calculates the standard deviation of a column of numbers. Only one row from the data stream will be kept after this function is called, and all the rest rows will be abandoned.

Arguments：

• Number <number>, auto-abstraction: UUID of NODE/EDGE, row index (starting from 0) of PATH/TABLE, or the first element of ARRAY

Returns：

• Stddev value <number>

ATTR (Numeric value)

Example: find the outbound 1-step paths from Card CA001, and calculate the standard deviation value of the amount of money transferred

n({_id == "CA001"}).re({@transfer} as pay).n({@card})
return stddev(pay.amount)