#hiroyannnn/sketch

#Installation

moon add hiroyannnn/sketch

import {
  "hiroyannnn/sketch" @sketch,
}

#Usage

#HyperLogLog — cardinality estimation

///|
test "HyperLogLog basic" {
  let hll = try! @sketch.HyperLogLog::new()
  for i in 0..<1000 {
    hll.add("item-\{i}")
  }
  let est = hll.count()
  // Estimate within ~2 % of 1000
  assert_true(est > 950.0 && est < 1050.0)
}

///|
test "HyperLogLog merge" {
  let a = try! @sketch.HyperLogLog::new()
  let b = try! @sketch.HyperLogLog::new()
  a.add("x")
  b.add("y")
  let merged = try! a.merge(b)
  assert_true(merged.count() >= 1.0)
}

///|
test "HyperLogLog invalid precision" {
  inspect(
    try! @sketch.HyperLogLog::new(precision=3),
    content="Err(InvalidPrecision)",
  )
}

#Count-Min Sketch — frequency estimation

///|
test "CountMinSketch basic" {
  let cm = try! @sketch.CountMinSketch::new()
  cm.add("apple", count=5)
  cm.add("banana")
  assert_true(cm.estimate("apple") >= 5)
  assert_true(cm.estimate("banana") >= 1)
}

///|
test "CountMinSketch merge" {
  let cm1 = try! @sketch.CountMinSketch::new()
  let cm2 = try! @sketch.CountMinSketch::new()
  cm1.add("x", count=3)
  cm2.add("x", count=4)
  let merged = try! cm1.merge(cm2)
  assert_true(merged.estimate("x") >= 7)
}

#Cuckoo Filter — set membership

///|
test "CuckooFilter basic" {
  let cf = @sketch.CuckooFilter::new()
  assert_true(cf.insert("hello"))
  assert_true(cf.contains("hello"))
  assert_true(!cf.contains("world"))
  assert_true(cf.remove("hello"))
  assert_true(!cf.contains("hello"))
}

#API reference

#SketchError

#HyperLogLog

#CountMinSketch

#CuckooFilter

#Acknowledgments

#License