* feat(family-12): add 13 Statistik/Regression indicators
Brings the Price Statistics family to 20 indicators (7 → 20) and the
total catalogue to 84 (71 → 84). Every indicator ships in the Rust
core plus Python, Node, and WASM bindings with full streaming ↔ batch
parity, fuzz coverage, and benches.
Scalar (f64 → f64):
- Variance, CoefficientOfVariation: rolling population variance and
its dimensionless ratio with the mean. O(1) updates.
- Skewness, Kurtosis: rolling Pearson skewness and excess kurtosis,
derived from running sums of x, x², x³, x⁴ via the binomial
identities — also O(1) per bar.
- StandardError, DetrendedStdDev: standard error of estimate (n − 2)
and population StdDev (n) of OLS residuals, sharing the LinReg
O(1) sliding sums.
- RSquared: coefficient of determination of the rolling OLS fit; the
trend-quality filter, clamped to [0, 1].
- MedianAbsoluteDeviation: robust dispersion estimator; O(period log
period) per emission via two in-place sorts of a reusable scratch
buffer.
- Autocorrelation(period, lag): rolling lag-k Pearson autocorrelation.
- HurstExponent(period, chunks): R/S-analysis trend-persistence
estimator clamped to [0, 1].
Pair indicators (Input = (f64, f64)):
- PearsonCorrelation: rolling cross-series Pearson, O(1).
- Beta: rolling OLS slope of asset vs. benchmark (CAPM).
- SpearmanCorrelation: rolling rank correlation with mid-rank tie
handling; O(period log period).
Touchpoints:
- crates/wickra-core: 13 new indicator modules + mod.rs / lib.rs
re-exports.
- bindings/python: pyclasses + add_class registration + __init__.py
import & __all__ updates. The pair indicators expose
update(x, y) and batch(x, y) over two equally-sized numpy arrays.
- bindings/node: scalar indicators via node_scalar_indicator! macro;
pair indicators via new node_pair_indicator! macro; explicit
structs for Autocorrelation and HurstExponent (two-arg ctors).
index.js extended with the new exports.
- bindings/wasm: scalar wrappers via wasm_scalar_indicator!; pair
wrappers via new wasm_pair_indicator! macro.
- fuzz: every scalar drove through the generic helper; pair
indicators stress-tested by pairing adjacent samples of the fuzz
input.
- Python tests (test_new_indicators.py): added to SCALAR
parametrisation, plus algebraic reference values
(variance of [2,4,6] = 8/3, MAD ignoring outlier = 0, monotone
non-linear Spearman = 1, two-to-one Beta = 2, etc.) and a
streaming-vs-batch test for the pair indicators.
- Node tests (indicators.test.js): extended the scalar factories
map and added a pair-indicator section with the same algebraic
reference values.
- crates/wickra/benches: bench_scalar entries for all 10 single-
input new indicators.
- README: counter 71 → 84; Price Statistics family-table row
expanded with the 13 new indicators.
- CHANGELOG: Unreleased section documents the family addition.
Wiki drafts (ghost-ignored, manual sync to wickra.wiki at release
time): indicator-ideas/families/wiki/family-12-statistik-regression/
contains 13 deep-dive pages plus _Sidebar / Indicators-Overview /
Warmup-Periods / Home fragments for the curator merge.
cargo check --workspace --all-features: clean.
* fix(family-12): remove unreachable defensive guards in hurst_exponent
The three guards (m < 2 continue, end > buf.len() break, denom == 0.0
return) are by-construction unreachable given the constructor invariant
period >= 2 * chunks: m = period / k for k in 1..=chunks always
satisfies m >= 2 and end = (c+1) * m <= k * m <= period = buf.len(),
and m_1 = period and m_2 = period / 2 are always distinct so the slope
denominator is strictly positive. Removing them brings codecov/patch
back to 100%.
kingchenc
05fcdd9a5e