Struct Median 

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

A median filter over the most recent N readings.

A single bad sample - a spike from electrical noise or a flaky contact - drags a mean or an exponential average off course, because it is blended into the result. The median ignores it: one outlier cannot move the middle value of a sorted window. That makes a Median the right filter when the noise is occasional spikes rather than steady jitter; for steady jitter reach for Smoother instead. Keep the window small and odd (3, 5, 7) so there is a single middle reading; with an even N the median is the average of the two middle readings. A wide window rejects longer bursts and lags a real step by half its length, so a filter of 32 passes a new level 16 readings late. with_capacity keeps fewer than N.

A reading that is not a finite number, such as the NaN a failed sensor reports, is not kept.

Examples

use pamoja_kit::Median;

let mut filtered = Median::<5>::new();
// A lone spike among steady readings is rejected.
for reading in [10.0, 10.0, 99.0, 10.0, 10.0] {
    filtered.update(reading);
}
assert_eq!(filtered.median(), Some(10.0));

Implementations

impl<const N: usize> Median<N>

pub fn new() -> Self

Creates an empty median filter over a window of N readings.

Returns

A filter holding no readings yet.

pub fn with_capacity(capacity: usize) -> Self

Creates an empty median filter that keeps at most capacity readings.

The storage is still N readings; this is how a filter sized at run time keeps fewer.

Arguments

• capacity - the most readings to keep. One above N is taken as N.

Returns

A filter holding no readings yet.

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

Adds a reading and returns the median of the current window.

Arguments

• reading - the latest raw reading.

Returns

The median of the readings now in the window. With a zero-length window the reading passes through unchanged, and so does one that is not a finite number while the window is empty.

pub fn push(&mut self, reading: f32)

Adds a reading to the window, evicting the oldest once it is full.

Arguments

• reading - the latest raw reading. One that is not a finite number is not kept.

pub fn capacity(&self) -> usize

Returns the most readings the filter keeps: N, or less when made with with_capacity.

pub fn median(&self) -> Option<f32>

Returns the median of the readings in the window, or None if it is empty.

Returns

The middle reading of the sorted window for an odd count, the average of the two middle readings for an even count, or None before any reading.

pub fn len(&self) -> usize

Returns the number of readings currently held, at most the capacity.

pub fn is_empty(&self) -> bool

Returns true if the filter holds no readings.

Trait Implementations

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

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

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

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

Formats the value using the given formatter.

impl<const N: usize> Default for Median<N>

fn default() -> Self

Returns the “default value” for a type.