Struct ProjectionBands 

pub struct ProjectionBands { /* private fields */ }

Projection Bands: forward-projected high/low envelope.

Mel Widner (“Projection Bands and the Projection Oscillator”, Technical Analysis of Stocks & Commodities, May 1995) fits a separate linear regression to the highs and to the lows over the last period bars, then slides every bar’s high and low forward to the current bar along its own slope. The upper band is the maximum of the projected highs, the lower band the minimum of the projected lows:

slope_h = OLS slope of (x, high) over the window
slope_l = OLS slope of (x, low)  over the window
// bar i (0 = oldest, period-1 = newest) is (period-1-i) bars in the past
upper   = max over i of [ high_i + slope_h · (period-1-i) ]
lower   = min over i of [ low_i  + slope_l · (period-1-i) ]
middle  = (upper + lower) / 2

Unlike LinRegChannel and StandardErrorBands — which wrap a single close-regression endpoint by a dispersion statistic — Projection Bands are built from the extremes: the envelope adapts to the trend’s slope yet always contains every projected high and low, so by construction price never pierces the bands within the window. A flat slope reduces the bands to the rolling highest-high / lowest-low (a Donchian channel); a steep slope tilts the whole envelope with the trend.

Example

use wickra_core::{Candle, Indicator, ProjectionBands};

let mut indicator = ProjectionBands::new(14).unwrap();
let mut last = None;
for i in 0..30 {
    let base = 100.0 + f64::from(i);
    let candle =
        Candle::new(base, base + 2.0, base - 2.0, base + 1.0, 10.0, i64::from(i)).unwrap();
    last = indicator.update(candle);
}
assert!(last.is_some());

Implementations

impl ProjectionBands

pub fn new(period: usize) -> Result<Self>

Construct new Projection Bands.

Errors

Returns Error::InvalidPeriod if period < 2 (a regression slope needs at least two points).

pub const fn period(&self) -> usize

Configured period.

Trait Implementations

impl Clone for ProjectionBands

fn clone(&self) -> ProjectionBands

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ProjectionBands

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

Formats the value using the given formatter.

impl Indicator for ProjectionBands

type Input = Candle

Type of one input data point (typically f64 for a price, or Candle / Tick).

type Output = ProjectionBandsOutput

Type of one output value.

fn update(&mut self, candle: Candle) -> Option<ProjectionBandsOutput>

Feed one new data point into the indicator and return the freshly computed output, or None if the indicator is still warming up.

fn reset(&mut self)

Reset all internal state, leaving the indicator equivalent to a freshly constructed instance with the same parameters.

fn warmup_period(&self) -> usize

Number of inputs required before the first non-None output can be produced.

fn is_ready(&self) -> bool

Whether the indicator has emitted at least one value since the last reset.

fn name(&self) -> &'static str

Stable, human-readable indicator name. Used by chaining and diagnostics.