Array of Doubles sketch set operations

Combine two array_of_doubles() sketches into a new compact array_of_doubles_sketch result, without mutating either input. a and b must be Array of Doubles sketches created with the same seed (a mismatch raises datasketches_seed_mismatch).

Usage

array_of_doubles_union(a, b, lg_k = NULL)

array_of_doubles_intersection(a, b)

array_of_doubles_difference(a, b)

Arguments

a, b

array_of_doubles_sketch objects created with the same seed.

lg_k

For array_of_doubles_union(), log2 of the nominal number of entries for the union's internal sketch, a single whole number in [5, 26]. Defaults to the larger of a and b's configured lg_k (or 12 for compact inputs).

Value

A compact array_of_doubles_sketch object.

Details

• array_of_doubles_union(a, b) estimates the size of the union union(A, B). a and b must also share the same num_values (a mismatch raises datasketches_incompatible_sketch); value arrays for matching keys are combined by element-wise sum.

• array_of_doubles_intersection(a, b) estimates the size of the intersection intersection(A, B), with the same num_values requirement and combining rule as array_of_doubles_union().

• array_of_doubles_difference(a, b) estimates the size of the set difference A \\ B (elements in A but not B), retaining a's value arrays unchanged for the retained keys.

Examples

a <- array_of_doubles(1:1000, runif(1000))
b <- array_of_doubles(501:1500, runif(1000))
array_of_doubles_union(a, b)$column_sums()
#> [1] 1005.581
array_of_doubles_intersection(a, b)$estimate()
#> [1] 500
array_of_doubles_difference(a, b)$estimate()
#> [1] 500