Types

HLL = object exactMaxBytes: int sparseMaxBytes: int card: uint64 encoding: HLLEncoding reglen: int registers: seq[byte]: HyperLogLog data structure. Allows getting approximate cardinality of large sets in constant time and memory. Source Edit

Procs

proc `+`(a, b: HLL): HLL {....raises: [], tags: [].}

Alias for union(a, b)

See also:

union proc

Source Edit

proc add[A](hll: var HLL; key: A): bool {.discardable.}

Alias for incl.

See also:

incl proc

Source Edit

proc card(hlls: varargs[HLL]): int {....raises: [], tags: [].}

Returns the number of elements in the union of all given hlls. This is equivalent to union(hlls).len, but a little bit more performant.

See also:

len proc
getLen proc

Source Edit

proc clear(hll: var HLL) {....raises: [], tags: [].}

Removes all elements from hll (without freeing up memory, so it can be reused). Source Edit

proc getLen(hll: var HLL): int {....raises: [], tags: [].}

Returns the number of elements in hll. This will use cached cardinality if it's available, otherwise it will be computed and stored (so this call has side effects).

See also:

card proc
getLen proc

Source Edit

proc hash(hll: HLL): Hash {....raises: [], tags: [].}

Returns hash of hll. Source Edit

proc incl[A](hll: var HLL; key: A): bool {.discardable.}

Includes an element key in hll. Returns true if the data structure was modified by this operation. Source Edit

proc initHLL(sparseMaxBytes: int = 3000; exactMaxBytes: int = 0): HLL {.
    ...raises: [], tags: [].}

Creates an HLL object. By default, HLL is created using sparse encoding (unless exactMaxBytes is greater than 0). This will be upgraded to the sparse/dense representation as needed. You can pass sparseMaxBytes/exactMaxBytes arguments to specify the actual thresholds. Source Edit

func len(hll: HLL): int {....raises: [], tags: [].}

Returns the number of elements in hll. This will use cached cardinality if it's available, but won't update it, so it's side-effect free.

See also:

card proc
getLen proc

Source Edit

proc merge(hlls: varargs[HLL]): HLL {....raises: [], tags: [].}

Alias for union(hlls)

See also:

union proc

Source Edit

proc toBytes(hll: HLL): seq[byte] {....raises: [], tags: [].}

Serializes hll to a byte array, so it can be stored and deserialized later.

See also:

toHLL proc

Source Edit

proc toHLL(bytes: seq[byte]; sparseMaxBytes: int = 3000; exactMaxBytes: int = 0): HLL {.
    ...raises: [], tags: [].}

Restores HyperLogLog from a byte array bytes.

See also:

toBytes proc

Source Edit

proc union(hlls: varargs[HLL]): HLL {....raises: [], tags: [].}

Returns the union of the HyperLogLogs hlls. Source Edit

src/hyperloglog

Types

Procs