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Ensure Uniform constructed on bounded interval #218

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May 25, 2024
Merged

Ensure Uniform constructed on bounded interval #218

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ad5219e
feat: extend StatsError for finiteness
YeungOnion Apr 21, 2024
726316c
feat: reject constructing Uniform of infinite support
YeungOnion Apr 21, 2024
07c1f8e
test: ensure test suite matches behavior for restricting bounded Uniform
YeungOnion Apr 21, 2024
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57 changes: 17 additions & 40 deletions src/distribution/uniform.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@ impl Uniform {
///
/// # Errors
///
/// Returns an error if `min` or `max` are `NaN`
/// Returns an error if `min` or `max` are `NaN` or unbounded
///
/// # Examples
///
Expand All @@ -44,12 +44,21 @@ impl Uniform {
///
/// result = Uniform::new(f64::NAN, f64::NAN);
/// assert!(result.is_err());
///
/// result = Uniform::new(f64::NEG_INFINITY, 1.0);
/// assert!(result.is_err());
/// ```
pub fn new(min: f64, max: f64) -> Result<Uniform> {
if min > max || min.is_nan() || max.is_nan() {
Err(StatsError::BadParams)
} else {
Ok(Uniform { min, max })
if min.is_nan() || max.is_nan() {
return Err(StatsError::BadParams);
}

match (min.is_finite(), max.is_finite(), min < max) {
(false, false, _) => Err(StatsError::ArgFinite("min and max")),
(false, true, _) => Err(StatsError::ArgFinite("min")),
(true, false, _) => Err(StatsError::ArgFinite("max")),
(true, true, false) => Err(StatsError::ArgLteArg("min", "max")),
(true, true, true) => Ok(Uniform { min, max }),
}
}
}
Expand Down Expand Up @@ -94,10 +103,6 @@ impl ContinuousCDF<f64, f64> for Uniform {
1.0
} else if x >= self.max {
0.0
} else if x.is_infinite() && self.max.is_infinite() {
0.0
} else if self.max.is_infinite() {
1.0
} else {
(self.max - x) / (self.max - self.min)
}
Expand Down Expand Up @@ -256,7 +261,7 @@ mod tests {

fn try_create(min: f64, max: f64) -> Uniform {
let n = Uniform::new(min, max);
assert!(n.is_ok());
assert!(n.is_ok(), "failed create over interval [{}, {}]", min, max);
n.unwrap()
}

Expand Down Expand Up @@ -296,19 +301,19 @@ mod tests {

#[test]
fn test_create() {
create_case(0.0, 0.0);
create_case(0.0, 0.1);
create_case(0.0, 1.0);
create_case(10.0, 10.0);
create_case(-5.0, 11.0);
create_case(-5.0, 100.0);
}

#[test]
fn test_bad_create() {
bad_create_case(0.0, 0.0);
bad_create_case(f64::NAN, 1.0);
bad_create_case(1.0, f64::NAN);
bad_create_case(f64::NAN, f64::NAN);
bad_create_case(0.0, f64::INFINITY);
bad_create_case(1.0, 0.0);
}

Expand All @@ -319,7 +324,6 @@ mod tests {
test_case(0.0, 2.0, 1.0 / 3.0, variance);
test_almost(0.1, 4.0, 1.2675, 1e-15, variance);
test_case(10.0, 11.0, 1.0 / 12.0, variance);
test_case(0.0, f64::INFINITY, f64::INFINITY, variance);
}

#[test]
Expand All @@ -330,7 +334,6 @@ mod tests {
test_almost(0.1, 4.0, 1.360976553135600743431, 1e-15, entropy);
test_case(1.0, 10.0, 2.19722457733621938279, entropy);
test_case(10.0, 11.0, 0.0, entropy);
test_case(0.0, f64::INFINITY, f64::INFINITY, entropy);
}

#[test]
Expand All @@ -341,7 +344,6 @@ mod tests {
test_case(0.1, 4.0, 0.0, skewness);
test_case(1.0, 10.0, 0.0, skewness);
test_case(10.0, 11.0, 0.0, skewness);
test_case(0.0, f64::INFINITY, 0.0, skewness);
}

#[test]
Expand All @@ -352,7 +354,6 @@ mod tests {
test_case(0.1, 4.0, 2.05, mode);
test_case(1.0, 10.0, 5.5, mode);
test_case(10.0, 11.0, 10.5, mode);
test_case(0.0, f64::INFINITY, f64::INFINITY, mode);
}

#[test]
Expand All @@ -363,15 +364,11 @@ mod tests {
test_case(0.1, 4.0, 2.05, median);
test_case(1.0, 10.0, 5.5, median);
test_case(10.0, 11.0, 10.5, median);
test_case(0.0, f64::INFINITY, f64::INFINITY, median);
}

#[test]
fn test_pdf() {
let pdf = |arg: f64| move |x: Uniform| x.pdf(arg);
test_case(0.0, 0.0, 0.0, pdf(-5.0));
test_case(0.0, 0.0, f64::INFINITY, pdf(0.0));
test_case(0.0, 0.0, 0.0, pdf(5.0));
test_case(0.0, 0.1, 0.0, pdf(-5.0));
test_case(0.0, 0.1, 10.0, pdf(0.05));
test_case(0.0, 0.1, 0.0, pdf(5.0));
Expand All @@ -386,17 +383,11 @@ mod tests {
test_case(-5.0, 100.0, 0.009523809523809523809524, pdf(-5.0));
test_case(-5.0, 100.0, 0.009523809523809523809524, pdf(0.0));
test_case(-5.0, 100.0, 0.0, pdf(101.0));
test_case(0.0, f64::INFINITY, 0.0, pdf(-5.0));
test_case(0.0, f64::INFINITY, 0.0, pdf(10.0));
test_case(0.0, f64::INFINITY, 0.0, pdf(f64::INFINITY));
}

#[test]
fn test_ln_pdf() {
let ln_pdf = |arg: f64| move |x: Uniform| x.ln_pdf(arg);
test_case(0.0, 0.0, f64::NEG_INFINITY, ln_pdf(-5.0));
test_case(0.0, 0.0, f64::INFINITY, ln_pdf(0.0));
test_case(0.0, 0.0, f64::NEG_INFINITY, ln_pdf(5.0));
test_case(0.0, 0.1, f64::NEG_INFINITY, ln_pdf(-5.0));
test_almost(0.0, 0.1, 2.302585092994045684018, 1e-15, ln_pdf(0.05));
test_case(0.0, 0.1, f64::NEG_INFINITY, ln_pdf(5.0));
Expand All @@ -411,38 +402,27 @@ mod tests {
test_case(-5.0, 100.0, -4.653960350157523371101, ln_pdf(-5.0));
test_case(-5.0, 100.0, -4.653960350157523371101, ln_pdf(0.0));
test_case(-5.0, 100.0, f64::NEG_INFINITY, ln_pdf(101.0));
test_case(0.0, f64::INFINITY, f64::NEG_INFINITY, ln_pdf(-5.0));
test_case(0.0, f64::INFINITY, f64::NEG_INFINITY, ln_pdf(10.0));
test_case(0.0, f64::INFINITY, f64::NEG_INFINITY, ln_pdf(f64::INFINITY));
}

#[test]
fn test_cdf() {
let cdf = |arg: f64| move |x: Uniform| x.cdf(arg);
test_case(0.0, 0.0, 0.0, cdf(0.0));
test_case(0.0, 0.1, 0.5, cdf(0.05));
test_case(0.0, 1.0, 0.5, cdf(0.5));
test_case(0.0, 10.0, 0.1, cdf(1.0));
test_case(0.0, 10.0, 0.5, cdf(5.0));
test_case(-5.0, 100.0, 0.0, cdf(-5.0));
test_case(-5.0, 100.0, 0.04761904761904761904762, cdf(0.0));
test_case(0.0, f64::INFINITY, 0.0, cdf(10.0));
test_case(0.0, f64::INFINITY, 1.0, cdf(f64::INFINITY));
}

#[test]
fn test_inverse_cdf() {
let inverse_cdf = |arg: f64| move |x: Uniform| x.inverse_cdf(arg);
test_case(0.0, 0.0, 0.0, inverse_cdf(0.0));
test_case(0.0, 0.0, 0.0, inverse_cdf(1.0));
test_case(0.0, 0.1, 0.05, inverse_cdf(0.5));
test_case(0.0, 10.0, 5.0, inverse_cdf(0.5));
test_case(1.0, 10.0, 1.0, inverse_cdf(0.0));
test_case(1.0, 10.0, 4.0, inverse_cdf(1.0 / 3.0));
test_case(1.0, 10.0, 10.0, inverse_cdf(1.0));
test_case(f64::NEG_INFINITY, f64::INFINITY, f64::NEG_INFINITY, inverse_cdf(0.0));
test_case(0.0, f64::INFINITY, 0.0, inverse_cdf(0.0));
test_case(0.0, f64::INFINITY, f64::INFINITY, inverse_cdf(1.0));
}

#[test]
Expand All @@ -461,15 +441,12 @@ mod tests {
#[test]
fn test_sf() {
let sf = |arg: f64| move |x: Uniform| x.sf(arg);
test_case(0.0, 0.0, 1.0, sf(0.0));
test_case(0.0, 0.1, 0.5, sf(0.05));
test_case(0.0, 1.0, 0.5, sf(0.5));
test_case(0.0, 10.0, 0.9, sf(1.0));
test_case(0.0, 10.0, 0.5, sf(5.0));
test_case(-5.0, 100.0, 1.0, sf(-5.0));
test_case(-5.0, 100.0, 0.9523809523809523, sf(0.0));
test_case(0.0, f64::INFINITY, 1.0, sf(10.0));
test_case(0.0, f64::INFINITY, 0.0, sf(f64::INFINITY));
}

#[test]
Expand Down
3 changes: 3 additions & 0 deletions src/error.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,8 @@ use std::fmt;
pub enum StatsError {
/// Generic bad input parameter error
BadParams,
/// An argument must be finite
ArgFinite(&'static str),
/// An argument should have been positive and was not
ArgMustBePositive(&'static str),
/// An argument should have been non-negative and was not
Expand Down Expand Up @@ -58,6 +60,7 @@ impl fmt::Display for StatsError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
StatsError::BadParams => write!(f, "Bad distribution parameters"),
StatsError::ArgFinite(s) => write!(f, "Argument {} must be finite", s),
StatsError::ArgMustBePositive(s) => write!(f, "Argument {} must be positive", s),
StatsError::ArgNotNegative(s) => write!(f, "Argument {} must be non-negative", s),
StatsError::ArgIntervalIncl(s, min, max) => {
Expand Down
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