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tison pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/datasketches-rust.git
The following commit(s) were added to refs/heads/main by this push:
new f0d997e chore: fine tune binomial_bounds.rs code (#103)
f0d997e is described below
commit f0d997e2abc24014311e1ee74f54107c6a054c99
Author: tison <[email protected]>
AuthorDate: Fri Feb 20 20:24:14 2026 +0800
chore: fine tune binomial_bounds.rs code (#103)
Signed-off-by: tison <[email protected]>
---
datasketches/src/common/binomial_bounds.rs | 74 ++++++++++--------------------
1 file changed, 25 insertions(+), 49 deletions(-)
diff --git a/datasketches/src/common/binomial_bounds.rs
b/datasketches/src/common/binomial_bounds.rs
index c2b7d74..2950d1d 100644
--- a/datasketches/src/common/binomial_bounds.rs
+++ b/datasketches/src/common/binomial_bounds.rs
@@ -275,7 +275,7 @@ static UB_EQUIV_TABLE: [f64; 363] = [
/// # Arguments
///
/// * `num_samples`: The number of samples in the sample set.
-/// * `theta`: The sampling probability. Must be in the range (0.0, 1.0].
+/// * `theta`: The sampling probability. Must be in the range `(0.0, 1.0]`.
/// * `num_std_dev`: The number of standard deviations for confidence bounds.
///
/// # Returns
@@ -284,13 +284,17 @@ static UB_EQUIV_TABLE: [f64; 363] = [
///
/// # Errors
///
-/// Returns an error if `theta` is not in the range (0.0, 1.0].
+/// Returns an error if `theta` is not in the range `(0.0, 1.0]`.
pub(crate) fn lower_bound(
num_samples: u64,
theta: f64,
num_std_dev: NumStdDev,
) -> Result<f64, Error> {
- check_theta(theta)?;
+ if theta <= 0.0 || theta > 1.0 {
+ return Err(Error::invalid_argument(format!(
+ "theta must be in the range (0.0, 1.0], got {theta}"
+ )));
+ }
let estimate = num_samples as f64 / theta;
let lb = compute_approx_binomial_lower_bound(num_samples, theta,
num_std_dev);
@@ -325,7 +329,12 @@ pub(crate) fn upper_bound(
if no_data_seen {
return Ok(0.0);
}
- check_theta(theta)?;
+
+ if theta <= 0.0 || theta > 1.0 {
+ return Err(Error::invalid_argument(format!(
+ "theta must be in the range (0.0, 1.0], got {theta}"
+ )));
+ }
let estimate = num_samples as f64 / theta;
let ub = compute_approx_binomial_upper_bound(num_samples, theta,
num_std_dev);
@@ -360,6 +369,7 @@ fn cont_classic_ub(num_samples: u64, theta: f64,
num_std_devs: f64) -> f64 {
/// # Limitations
///
/// Outside of the valid input range, two different bad things will happen:
+///
/// 1. Because we are not using logarithms, the values of intermediate
quantities will exceed the
/// dynamic range of doubles.
/// 2. Even if that problem were fixed, the running time of this procedure is
essentially linear in
@@ -548,21 +558,6 @@ fn compute_approx_binomial_upper_bound(
special_n_prime_f(num_samples, theta, delta).unwrap_or(num_samples + 1) as
f64 // no need to round
}
-/// Validates that theta is in the valid range [0.0, 1.0].
-///
-/// # Errors
-///
-/// Returns an error if theta < 0.0 or theta > 1.0.
-fn check_theta(theta: f64) -> Result<(), Error> {
- if (theta <= 0.0) || (theta > 1.0) {
- return Err(Error::invalid_argument(format!(
- "theta must be in the range [0.0, 1.0]: {}",
- theta
- )));
- }
- Ok(())
-}
-
#[cfg(test)]
mod tests {
use super::*;
@@ -679,19 +674,18 @@ mod tests {
fn check_bounds() {
let mut i = 0;
+ fn assert_approx_equal(ci: NumStdDev, j: usize, expected: f64, actual:
f64) {
+ let ratio = actual / expected;
+ assert!(
+ (ratio - 1.0).abs() < TOL,
+ "ci={ci:?}, j={j}: expected {expected}, got {actual},
ratio={ratio}",
+ );
+ }
+
for ci in [NumStdDev::One, NumStdDev::Two, NumStdDev::Three] {
let arr = run_test_aux(20, ci, 1e-3);
for j in 0..5 {
- let ratio = arr[j] / STD[i][j];
- assert!(
- (ratio - 1.0).abs() < TOL,
- "ci={:?}, j={}: expected {}, got {}, ratio={}",
- ci,
- j,
- STD[i][j],
- arr[j],
- ratio
- );
+ assert_approx_equal(ci, j, STD[i][j], arr[j]);
}
i += 1;
}
@@ -699,16 +693,7 @@ mod tests {
for ci in [NumStdDev::One, NumStdDev::Two, NumStdDev::Three] {
let arr = run_test_aux(200, ci, 1e-5);
for j in 0..5 {
- let ratio = arr[j] / STD[i][j];
- assert!(
- (ratio - 1.0) < TOL,
- "ci={:?}, j={}: expected {}, got {}, ratio={}",
- ci,
- j,
- STD[i][j],
- arr[j],
- ratio
- );
+ assert_approx_equal(ci, j, STD[i][j], arr[j]);
}
i += 1;
}
@@ -716,16 +701,7 @@ mod tests {
for ci in [NumStdDev::One, NumStdDev::Two, NumStdDev::Three] {
let arr = run_test_aux(2000, ci, 1e-7);
for j in 0..5 {
- let ratio = arr[j] / STD[i][j];
- assert!(
- (ratio - 1.0).abs() < TOL,
- "ci={:?}, j={}: expected {}, got {}, ratio={}",
- ci,
- j,
- STD[i][j],
- arr[j],
- ratio
- );
+ assert_approx_equal(ci, j, STD[i][j], arr[j]);
}
i += 1;
}
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