Struct Anomaly 

pub struct Anomaly<const N: usize> { /* private fields */ }

Flags a reading that lies far from the recent norm.

“Tell me when something is off” needs a baseline: a reading is suspicious only relative to what is usual. An Anomaly keeps a rolling window of recent readings and flags one that sits more than a chosen number of standard deviations from their mean - the three-sigma rule, the standard z-score test, with the threshold left to the caller (3.0 is the usual choice). It is dependency-free: instead of taking a square root it compares the squared deviation against the squared threshold, which is the same test.

With a perfectly flat baseline the spread is zero, so any change at all reads as anomalous; real sensor noise gives a non-zero baseline, where this is not an issue.

Examples

use pamoja_kit::Anomaly;

let mut watch = Anomaly::<8>::new(3.0);
// Establish a steady baseline.
for reading in [10.0, 10.2, 9.8, 10.1, 9.9, 10.0, 10.2, 9.8] {
    watch.check(reading);
}
assert!(!watch.check(10.1)); // close to the norm: fine
assert!(watch.check(20.0)); // a far jump: flagged

Implementations

impl<const N: usize> Anomaly<N>

pub fn new(sigmas: f32) -> Self

Creates a detector that flags readings beyond sigmas standard deviations.

Arguments

• sigmas - the threshold in standard deviations; 3.0 is the common three-sigma rule. Its magnitude is used.

Returns

A detector with an empty history.

pub fn check(&mut self, reading: f32) -> bool

Tests a reading against the recent norm, then folds it into the history.

The reading is judged against the window of earlier readings, so the value being tested does not inflate its own baseline. Until at least two readings have been seen there is no spread to judge against, so nothing is flagged.

Arguments

• reading - the latest reading.

Returns

true if reading lies more than the configured standard deviations from the mean of the recent window.

pub fn len(&self) -> usize

Returns the number of readings in the baseline window so far.

pub fn is_empty(&self) -> bool

Returns true if no readings have been recorded yet.

Trait Implementations

impl<const N: usize> Clone for Anomaly<N>

fn clone(&self) -> Anomaly<N>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<const N: usize> Copy for Anomaly<N>

impl<const N: usize> Debug for Anomaly<N>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.