Struct CompactThetaSketch 

pub struct CompactThetaSketch { /* private fields */ }

An immutable, serializable snapshot of a theta sketch. Produced by super::ThetaSketch::compact, by any set operation’s result (ThetaUnion::get_result, ThetaIntersection::get_result, ThetaAnotB::compute), or by Self::deserialize.

Implementations

impl CompactThetaSketch

pub fn deserialize(bytes: &[u8]) -> Result<Self, SketchError>

Deserializes v1/v2/v3 (uncompressed) bytes. Upstream’s deserialize() auto-detects the serial version transparently, including v4 (compressed) — see Self::deserialize_compressed, which calls the exact same underlying routine; the two Rust names exist purely for call-site symmetry with serialize_compact/serialize_compressed.

Examples found in repository

examples/theta.rs (line 73)

fn main() {
    // Build two sketches representing two overlapping sets of user IDs.
    let mut visitors_day1 = ThetaSketchBuilder::new().lg_k(12).build().unwrap();
    for id in 0..10_000u64 {
        visitors_day1.update_u64(id);
    }

    let mut visitors_day2 = ThetaSketchBuilder::new().lg_k(12).build().unwrap();
    for id in 5_000..15_000u64 {
        visitors_day2.update_u64(id);
    }

    println!(
        "Day 1 unique visitors (estimate): {:.0}",
        visitors_day1.get_estimate()
    );
    println!(
        "Day 2 unique visitors (estimate): {:.0}",
        visitors_day2.get_estimate()
    );

    // Union: total unique visitors across both days.
    let mut union = ThetaUnionBuilder::new().lg_k(12).build().unwrap();
    union.update(&visitors_day1);
    union.update(&visitors_day2);
    let total_unique = union.get_result(true);
    println!(
        "Total unique visitors (union estimate): {:.0}",
        total_unique.get_estimate()
    );

    // Intersection: visitors who came back on day 2.
    let mut intersection = ThetaIntersection::new();
    intersection.update(&visitors_day1);
    intersection.update(&visitors_day2);
    match intersection.get_result(true) {
        Ok(returning) => println!(
            "Returning visitors (intersection estimate): {:.0}",
            returning.get_estimate()
        ),
        Err(e) => println!("No intersection result: {e}"),
    }

    // A-not-b: visitors who only came on day 1.
    let a_not_b = ThetaAnotB::new();
    let day1_only = a_not_b.compute(&visitors_day1, &visitors_day2, true);
    println!(
        "Day-1-only visitors (a-not-b estimate): {:.0}",
        day1_only.get_estimate()
    );

    // Jaccard similarity: how similar are the two days' visitor sets?
    let similarity = jaccard_similarity(&visitors_day1, &visitors_day2);
    println!(
        "Jaccard similarity: {:.3} (range [{:.3}, {:.3}])",
        similarity.estimate, similarity.lower_bound, similarity.upper_bound
    );

    // Serialize a compact sketch for storage/transmission, then restore it.
    let compact = visitors_day1.compact(true);
    let bytes = compact.serialize_compact();
    println!("Serialized day-1 sketch: {} bytes", bytes.len());
    let restored = apache_datasketches::theta::CompactThetaSketch::deserialize(&bytes).unwrap();
    println!("Restored estimate: {:.0}", restored.get_estimate());
}

pub fn deserialize_compressed(bytes: &[u8]) -> Result<Self, SketchError>

Deserializes v4 (compressed) bytes. See Self::deserialize — both methods call the same upstream auto-detecting deserialize().

pub fn get_estimate(&self) -> f64

Returns the current estimate of the number of distinct items in this sketch.

Examples found in repository

examples/theta.rs (line 39)

fn main() {
    // Build two sketches representing two overlapping sets of user IDs.
    let mut visitors_day1 = ThetaSketchBuilder::new().lg_k(12).build().unwrap();
    for id in 0..10_000u64 {
        visitors_day1.update_u64(id);
    }

    let mut visitors_day2 = ThetaSketchBuilder::new().lg_k(12).build().unwrap();
    for id in 5_000..15_000u64 {
        visitors_day2.update_u64(id);
    }

    println!(
        "Day 1 unique visitors (estimate): {:.0}",
        visitors_day1.get_estimate()
    );
    println!(
        "Day 2 unique visitors (estimate): {:.0}",
        visitors_day2.get_estimate()
    );

    // Union: total unique visitors across both days.
    let mut union = ThetaUnionBuilder::new().lg_k(12).build().unwrap();
    union.update(&visitors_day1);
    union.update(&visitors_day2);
    let total_unique = union.get_result(true);
    println!(
        "Total unique visitors (union estimate): {:.0}",
        total_unique.get_estimate()
    );

    // Intersection: visitors who came back on day 2.
    let mut intersection = ThetaIntersection::new();
    intersection.update(&visitors_day1);
    intersection.update(&visitors_day2);
    match intersection.get_result(true) {
        Ok(returning) => println!(
            "Returning visitors (intersection estimate): {:.0}",
            returning.get_estimate()
        ),
        Err(e) => println!("No intersection result: {e}"),
    }

    // A-not-b: visitors who only came on day 1.
    let a_not_b = ThetaAnotB::new();
    let day1_only = a_not_b.compute(&visitors_day1, &visitors_day2, true);
    println!(
        "Day-1-only visitors (a-not-b estimate): {:.0}",
        day1_only.get_estimate()
    );

    // Jaccard similarity: how similar are the two days' visitor sets?
    let similarity = jaccard_similarity(&visitors_day1, &visitors_day2);
    println!(
        "Jaccard similarity: {:.3} (range [{:.3}, {:.3}])",
        similarity.estimate, similarity.lower_bound, similarity.upper_bound
    );

    // Serialize a compact sketch for storage/transmission, then restore it.
    let compact = visitors_day1.compact(true);
    let bytes = compact.serialize_compact();
    println!("Serialized day-1 sketch: {} bytes", bytes.len());
    let restored = apache_datasketches::theta::CompactThetaSketch::deserialize(&bytes).unwrap();
    println!("Restored estimate: {:.0}", restored.get_estimate());
}

pub fn get_lower_bound(&self, num_std_dev: u8) -> Result<f64, SketchError>

Returns the lower bound of the confidence interval around Self::get_estimate. See ThetaSketch::get_lower_bound for the meaning of num_std_dev.

pub fn get_upper_bound(&self, num_std_dev: u8) -> Result<f64, SketchError>

Returns the upper bound of the confidence interval around Self::get_estimate. See ThetaSketch::get_lower_bound for the meaning of num_std_dev.

pub fn is_empty(&self) -> bool

Returns true if this sketch represents an empty set.

pub fn is_estimation_mode(&self) -> bool

Returns true if this sketch’s theta threshold is below 1.0 (i.e. Self::get_estimate is a statistical estimate rather than an exact count).

pub fn is_ordered(&self) -> bool

Returns true if this sketch’s retained entries are sorted by hash value.

pub fn get_theta(&self) -> f64

Returns the current theta threshold (1.0 if not in estimation mode).

pub fn get_num_retained(&self) -> u32

Returns the number of entries currently retained by this sketch.

pub fn serialize_compact(&self) -> Vec<u8>

Serializes in the v3 (uncompressed) format. Note: unlike the design spec’s initially-sketched signature, this takes no ordered parameter — upstream’s compact_theta_sketch::serialize() has none; orderedness is fixed when this sketch was created (e.g. via ThetaSketch::compact(ordered)).

Examples found in repository

examples/theta.rs (line 71)

fn main() {
    // Build two sketches representing two overlapping sets of user IDs.
    let mut visitors_day1 = ThetaSketchBuilder::new().lg_k(12).build().unwrap();
    for id in 0..10_000u64 {
        visitors_day1.update_u64(id);
    }

    let mut visitors_day2 = ThetaSketchBuilder::new().lg_k(12).build().unwrap();
    for id in 5_000..15_000u64 {
        visitors_day2.update_u64(id);
    }

    println!(
        "Day 1 unique visitors (estimate): {:.0}",
        visitors_day1.get_estimate()
    );
    println!(
        "Day 2 unique visitors (estimate): {:.0}",
        visitors_day2.get_estimate()
    );

    // Union: total unique visitors across both days.
    let mut union = ThetaUnionBuilder::new().lg_k(12).build().unwrap();
    union.update(&visitors_day1);
    union.update(&visitors_day2);
    let total_unique = union.get_result(true);
    println!(
        "Total unique visitors (union estimate): {:.0}",
        total_unique.get_estimate()
    );

    // Intersection: visitors who came back on day 2.
    let mut intersection = ThetaIntersection::new();
    intersection.update(&visitors_day1);
    intersection.update(&visitors_day2);
    match intersection.get_result(true) {
        Ok(returning) => println!(
            "Returning visitors (intersection estimate): {:.0}",
            returning.get_estimate()
        ),
        Err(e) => println!("No intersection result: {e}"),
    }

    // A-not-b: visitors who only came on day 1.
    let a_not_b = ThetaAnotB::new();
    let day1_only = a_not_b.compute(&visitors_day1, &visitors_day2, true);
    println!(
        "Day-1-only visitors (a-not-b estimate): {:.0}",
        day1_only.get_estimate()
    );

    // Jaccard similarity: how similar are the two days' visitor sets?
    let similarity = jaccard_similarity(&visitors_day1, &visitors_day2);
    println!(
        "Jaccard similarity: {:.3} (range [{:.3}, {:.3}])",
        similarity.estimate, similarity.lower_bound, similarity.upper_bound
    );

    // Serialize a compact sketch for storage/transmission, then restore it.
    let compact = visitors_day1.compact(true);
    let bytes = compact.serialize_compact();
    println!("Serialized day-1 sketch: {} bytes", bytes.len());
    let restored = apache_datasketches::theta::CompactThetaSketch::deserialize(&bytes).unwrap();
    println!("Restored estimate: {:.0}", restored.get_estimate());
}

pub fn serialize_compressed(&self) -> Vec<u8>

Serializes in the v4 (compressed) format.

Trait Implementations

impl Send for CompactThetaSketch

impl ThetaInput for CompactThetaSketch