Xuanwo commented on code in PR #23: URL: https://github.com/apache/datasketches-rust/pull/23#discussion_r2622905327
########## src/tdigest/sketch.rs: ########## @@ -0,0 +1,673 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +use byteorder::{ByteOrder, LE, ReadBytesExt}; +use std::cmp::Ordering; +use std::convert::identity; +use std::io::Cursor; + +use crate::error::SerdeError; +use crate::tdigest::serialization::*; + +const BUFFER_MULTIPLIER: usize = 4; + +/// T-Digest sketch for estimating quantiles and ranks. +/// +/// See the [module documentation](self) for more details. +#[derive(Debug, Clone, PartialEq)] +pub struct TDigest { + k: u16, + + reverse_merge: bool, + min: f64, + max: f64, + + centroids: Vec<Centroid>, + centroids_weight: u64, + centroids_capacity: usize, + buffer: Vec<f64>, +} + +impl Default for TDigest { + fn default() -> Self { + TDigest::new(Self::DEFAULT_K) + } +} + +impl TDigest { + /// The default value of K if one is not specified. + pub const DEFAULT_K: u16 = 200; + + /// Creates a tdigest instance with the given value of k. + /// + /// # Panics + /// + /// If k is less than 10 + pub fn new(k: u16) -> Self { + Self::make( + k, + false, + f64::INFINITY, + f64::NEG_INFINITY, + vec![], + 0, + vec![], + ) + } + + // for deserialization + fn make( + k: u16, + reverse_merge: bool, + min: f64, + max: f64, + mut centroids: Vec<Centroid>, + centroids_weight: u64, + mut buffer: Vec<f64>, + ) -> Self { + assert!(k >= 10, "k must be at least 10"); + + let fudge = if k < 30 { 30 } else { 10 }; Review Comment: Sorry, I haven't read the paper yet. Would it be possible to add a brief explanation to this? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
