Aggregates¶

class dark.aggregates.Count(key=None, na_policy=1)¶

Counts distinct values for given key. If key is not specified, simply counts all items in the query.

class dark.aggregates.Median(key, na_policy=1)¶

Given a vector V of length N, the median of V is the middle value of a sorted copy of V, V_sorted - i.e., V_sorted[(N-1)/2], when N is odd. When N is even, it is the average of the two middle values of V_sorted.

class dark.aggregates.Qu1(key, na_policy=1)¶

Calculates the q0.25.

class dark.aggregates.Qu3(key, na_policy=1)¶

Calculates the q0.75.

class dark.aggregates.NA¶

Policy against N/A values. To be used in Aggregate constructors:

Min('key', NA.skip).