Files
wickra/bindings/python
kingchenc 3ea0f12b7a feat: Family 04 Volatility — RVI / Parkinson / Garman-Klass / Rogers-Satchell / Yang-Zhang (#42)
* feat(rvi): add Relative Volatility Index

Donald Dorsey's RSI-shaped volatility gauge. Partitions the rolling
population standard deviation of close into "up" samples (close rose
since the previous bar) and "down" samples (close fell), Wilder-smooths
each side, and reports 100 * AvgUp / (AvgUp + AvgDown). Output bounded
on [0, 100]; saturates at 100 in pure uptrends, 0 in pure downtrends,
and falls back to 50 on a completely flat series (same undefined-RS
convention as RSI).

Single period parameter (default 10) drives both the stddev window and
the Wilder smoothing constant. First emit lands at index 2*period - 2
(2*period - 1 bars are needed: period to fill the stddev window plus
period - 1 to seed the Wilder averages, overlapping by one bar).

Touchpoints: rvi.rs + mod.rs + lib.rs re-export, PyRvi + __init__.py +
test_new_indicators SCALAR + test_known_values uptrend reference,
RviNode + index.d.ts/index.js + indicators.test.js factory +
reference, WasmRvi via scalar macro, scalar-fuzz target, bench_scalar
entry, README + CHANGELOG.

* feat(parkinson): add Parkinson Volatility

Michael Parkinson's (1980) high-low realised volatility estimator.
Under a driftless Geometric-Brownian-Motion assumption, the extreme
range of a bar carries roughly 5x the variance information of the
close-to-close estimator, so for a given statistical efficiency
Parkinson needs five times fewer samples.

Formula:
    sigma^2 = (1 / (4n * ln 2)) * Sum_{i=1..n} (ln(H_i / L_i))^2
    out     = sqrt(sigma^2) * sqrt(trading_periods) * 100

The output is annualised to a percent in the same style as
HistoricalVolatility (pass `trading_periods = 1` for the raw per-bar
sigma * 100 figure). Two parameters: `period` (default 20) for the
rolling window, `trading_periods` (default 252) for the annualisation
factor. First emit at index `period - 1`.

Touchpoints: parkinson.rs + mod.rs + lib.rs re-export,
PyParkinsonVolatility + __init__.py + test_new_indicators CANDLE_SCALAR
+ test_known_values zero-range reference, ParkinsonVolatilityNode +
index.d.ts/index.js + indicators.test.js factory + reference,
WasmParkinsonVolatility hand-rolled, candle-fuzz target,
bench_candle_input entry, README + CHANGELOG.

* feat(garman-klass): add Garman-Klass Volatility

Garman & Klass (1980) OHLC realised-volatility estimator. Extends
Parkinson's high-low estimator with an open-to-close term, lifting
statistical efficiency from ~5x to ~7.4x relative to close-to-close
stddev under driftless Geometric Brownian Motion.

Formula (per bar):
    s_t  = 0.5 * (ln(H_t / L_t))^2 - (2*ln(2) - 1) * (ln(C_t / O_t))^2
    out  = sqrt(max(mean(s_t over `period`), 0)) * sqrt(trading_periods) * 100

The per-bar sample can be marginally negative when the bar has a small
range relative to its open-to-close move; a max(., 0) clamp on the
rolling mean absorbs that and the FP cancellation noise before the
square root.

Still biased on data with meaningful overnight drift -- use Yang-Zhang
when gaps matter. Defaults: `period = 20`, `trading_periods = 252`
(annualised percent, same convention as HistoricalVolatility).

Touchpoints: garman_klass.rs + mod.rs + lib.rs re-export,
PyGarmanKlassVolatility + __init__.py + test_new_indicators
CANDLE_SCALAR + test_known_values zero-movement reference,
GarmanKlassVolatilityNode + index.d.ts/index.js + indicators.test.js
factory + reference, WasmGarmanKlassVolatility hand-rolled,
candle-fuzz target, bench_candle_input entry, README + CHANGELOG.

* feat(rogers-satchell): add Rogers-Satchell Volatility

Rogers, Satchell & Yoon (1994) OHLC realised-volatility estimator.
Unlike Garman-Klass, the per-bar sample is exact under arbitrary
Brownian drift -- the drift component cancels algebraically.

Formula (per bar):
    s_t  = ln(H_t / C_t) * ln(H_t / O_t) + ln(L_t / C_t) * ln(L_t / O_t)
    out  = sqrt(max(mean(s_t over `period`), 0)) * sqrt(trading_periods) * 100

Each per-bar sample is also non-negative by construction: with
`Candle::new` guaranteeing H >= max(O, L, C) and L <= min(O, H, C), the
four log factors have predictable signs (ln(H/.) >= 0, ln(L/.) <= 0),
so both products contribute >= 0. The max(., 0) clamp on the rolling
mean is only there to absorb FP cancellation.

Defaults: `period = 20`, `trading_periods = 252` (annualised percent,
same convention as HistoricalVolatility / Parkinson / Garman-Klass).

Touchpoints: rogers_satchell.rs + mod.rs + lib.rs re-export,
PyRogersSatchellVolatility + __init__.py + test_new_indicators
CANDLE_SCALAR + test_known_values zero-movement reference,
RogersSatchellVolatilityNode + index.d.ts/index.js + indicators.test.js
factory + reference, WasmRogersSatchellVolatility hand-rolled,
candle-fuzz target, bench_candle_input entry, README + CHANGELOG.

* feat(yang-zhang): add Yang-Zhang Volatility

Yang & Zhang (2000) drift- and gap-robust OHLC realised-volatility
estimator. Combines three independent components into a single estimate
with minimum variance:

    overnight    = sample_var(ln(O_t / C_{t-1}))   over n bars  (close-to-open)
    open_close   = sample_var(ln(C_t / O_t))       over n bars
    rs           = mean(ln(H/C)*ln(H/O) + ln(L/C)*ln(L/O)) over n bars
    sigma^2_YZ   = overnight + k*open_close + (1-k)*rs
    k            = 0.34 / (1.34 + (n+1)/(n-1))
    out          = sqrt(max(sigma^2_YZ, 0)) * sqrt(trading_periods) * 100

The overnight and open-to-close variances use Bessel's correction (the
sample estimator, divisor n-1), same convention as
HistoricalVolatility. The blending factor `k` is the one that
minimises estimator variance under driftless Geometric Brownian Motion
with overnight gaps.

This is the gold-standard OHLC estimator for assets with both
close-to-open gaps and intraday drift: equities, futures, and any
market that does not trade continuously. For pure intraday data (where
O_t == C_{t-1} and the open-to-close return is constant), the
overnight and open-close terms vanish and the estimator collapses to
(1-k) * Rogers-Satchell -- this is the indicator's
intraday_data_collapses_to_rs_only unit test.

Period >= 2 (Bessel correction needs >= 2 samples). First emit at
index `period` (the (period+1)-th bar): one bar seeds prev_close, the
next `period` fill the rolling windows. Defaults: `period = 20`,
`trading_periods = 252`.

Touchpoints: yang_zhang.rs + mod.rs + lib.rs re-export,
PyYangZhangVolatility + __init__.py + test_new_indicators
CANDLE_SCALAR + test_known_values zero-movement reference,
YangZhangVolatilityNode + index.d.ts/index.js + indicators.test.js
factory + reference, WasmYangZhangVolatility hand-rolled, candle-fuzz
target, bench_candle_input entry, README + CHANGELOG.

* fix(rvi): rename to RviVolatility to avoid clash with family-02 RVI

Family 02 (PR #40) ships a separate `Rvi` struct for Relative Vigor
Index. The two indicators have nothing to do with each other beyond
sharing the acronym, so disambiguate by giving the volatility one a
longer name everywhere:

- Rust crate: `Rvi`        -> `RviVolatility`
- Rust file:  `rvi.rs`     -> `rvi_volatility.rs`
- Python:     `RVI`        -> `RVIVolatility`
- Node:       `RVI`        -> `RVIVolatility`
- WASM:       `RVI`        -> `RVIVolatility`

Once the two PRs are both merged, callers get `wickra::Rvi` for Vigor
and `wickra::RviVolatility` for Volatility. The shorter `RVI` acronym
stays with the Momentum family per the existing wiki pages and the
implementation that shipped first.

Updates: rvi_volatility.rs (renamed), mod.rs, lib.rs re-export,
bindings/python/src/lib.rs + __init__.py + tests, bindings/node/src/lib.rs
+ index.d.ts + index.js + __tests__, bindings/wasm/src/lib.rs,
fuzz/fuzz_targets/indicator_update.rs, crates/wickra/benches/indicators.rs,
README family-table label, CHANGELOG entry.

* test(volatility): Rename test_rvi -> test_rvi_volatility + drop dead match arms

The Python test test_rvi_pure_uptrend_saturates_at_one_hundred was
calling ta.RVI() expecting the volatility version, but ta.RVI now
means Family 02's Relative Vigor Index (candle input). Renamed to
ta.RVIVolatility to match the binding rename done at merge time.

In all four OHLC volatility tests, the existing `match (r, a) { ...,
_ => panic!() }` arm is dead in passing runs (every aligned pair is
either (None, None) or (Some, Some)). Codecov flagged it as a patch
miss on each of parkinson / garman_klass / rogers_satchell /
yang_zhang. Refactored per CLAUDE.md cold-path guidance to
`assert_eq!(r.is_some(), a.is_some()); if let (Some, Some) ...`.
2026-05-25 18:18:20 +02:00
..

Wickra

CI codecov crates.io PyPI npm License: PolyForm-NC

Streaming-first technical indicators. Install with pip install wickra — no system dependencies.

Wickra is a multi-language technical-analysis library with a Rust core and bindings for Python, Node.js, and WebAssembly. Every indicator is a state machine that updates in O(1) per new data point, so live trading bots and historical backtests share the exact same implementation.

import numpy as np
import wickra as ta

# Batch: classic TA-Lib-style usage
prices = np.linspace(100, 200, 1000)
rsi = ta.RSI(14)
values = rsi.batch(prices)              # numpy array, NaN during warmup

# Streaming: same indicator, fed tick by tick
rsi = ta.RSI(14)
for price in live_feed:
    value = rsi.update(price)           # O(1) — no recomputation over history
    if value is not None and value > 70:
        print("overbought")

Why Wickra exists

The Python TA ecosystem has plenty of libraries — TA-Lib, pandas-ta, finta, talipp, tulipy — and every one of them shares the same blind spot:

Library Install pain Streaming Multi-language Active
★ Wickra clean yes Python + Node + WASM + Rust yes
TA-Lib (Python) yes (C deps) no no barely
pandas-ta clean no no slow
finta clean no no stale
ta-lib-python yes (C deps) no no barely
talipp clean yes no yes
Tulip Indicators yes (C deps) no partial stale
ooples (C#) clean no C# only yes

Wickra is the only library that combines all of: clean install, streaming, multi-language reach, and active maintenance.

Benchmark: how much faster is "streaming-first"?

The numbers below were measured on a single developer workstation and are not guaranteed to reproduce identically on different hardware — absolute µs values depend on CPU, memory clock and OS scheduler. Read them as relative speedups between libraries on identical input, not as a universal performance contract.

  • Reproduced on: Windows 11 Pro 26200, AMD Ryzen 9 9950X, 64 GB DDR5, Rust 1.92 (release profile, lto = "fat", codegen-units = 1), Python 3.12, Node 20.
  • Reproduce yourself: pip install -e bindings/python[bench] then python -m benchmarks.compare_libraries. The script auto-detects every installed peer library and runs them on the same generated inputs as Wickra. The CI job cross-library-bench runs the same script on every push and uploads the raw report as a build artefact.

Lower µs/op = faster. Wickra wins every batch category outright, and the streaming gap widens linearly with how much history a batch-only library has to recompute on every tick.

Batch — single full pass over a 20 000-bar series

Reading the table: each cell shows that library's runtime, plus how many times slower it is than Wickra in parentheses. marks the winner per row.

Indicator ★ Wickra finta talipp
SMA(20) 95.6 µs ★ 343.5 µs (3.6× slower) 7 640.6 µs (79.9× slower)
EMA(20) 64.6 µs ★ 223.1 µs (3.5× slower) 12 160.9 µs (188.2× slower)
RSI(14) 126.2 µs ★ 1 107.1 µs (8.8× slower) 15 792.2 µs (125.1× slower)
MACD(12, 26, 9) 119.0 µs ★ 531.8 µs (4.5× slower) 49 788.1 µs (418.2× slower)
Bollinger(20, 2.0) 105.3 µs ★ 812.0 µs (7.7× slower) 130 938.3 µs (1 243.7× slower)
ATR(14) 123.5 µs ★ 5 144.8 µs (41.7× slower) 28 816.0 µs (233.4× slower)

Streaming — per-tick latency after seeding with 5 000 historical bars

A batch-only library has to re-run its full indicator over the entire history on every new tick; Wickra updates state in O(1).

Indicator ★ Wickra (per tick) talipp (per tick)
RSI(14) 0.119 µs ★ 1.644 µs (13.8× slower)

TA-Lib and pandas-ta are not included here because both fail to install cleanly on Windows without C build tooling — which is precisely the install pain Wickra was built to remove. The benchmark script auto-detects every peer library it can find and runs them on the same inputs as Wickra; install them in your environment to see those rows light up too.

Run the suite yourself:

pip install -e bindings/python[bench]
python -m benchmarks.compare_libraries

Indicators

71 streaming-first indicators across eight families. Every one passes the batch == streaming equivalence test, reference-value tests, and reset semantics tests.

Family Indicators
Moving Averages SMA, EMA, WMA, DEMA, TEMA, HMA, KAMA, SMMA, TRIMA, ZLEMA, T3, VWMA
Momentum Oscillators RSI (Wilder), Stochastic, CCI, ROC, Williams %R, MFI, Awesome Oscillator, MOM, CMO, TSI, PMO, StochRSI, Ultimate Oscillator
Trend & Directional MACD, ADX (+DI/-DI), Aroon, TRIX, Aroon Oscillator, Vortex, Mass Index, Choppiness Index, Vertical Horizontal Filter
Price Oscillators PPO, DPO, Coppock, Accelerator Oscillator, Balance of Power
Volatility & Bands ATR, Bollinger Bands, Keltner Channels, Donchian Channels, NATR, StdDev, Ulcer Index, Historical Volatility, Bollinger Bandwidth, %B, True Range, Chaikin Volatility
Trailing Stops Parabolic SAR, SuperTrend, Chandelier Exit, Chande Kroll Stop, ATR Trailing Stop
Volume OBV, VWAP (cumulative + rolling), ADL, Volume-Price Trend, Chaikin Money Flow, Chaikin Oscillator, Force Index, Ease of Movement
Price Statistics Typical Price, Median Price, Weighted Close, Linear Regression, Linear Regression Slope, Z-Score, Linear Regression Angle

Adding a new indicator means implementing one trait in Rust; all four bindings inherit it automatically.

Languages

Binding Install Example
Python (PyO3) pip install wickra examples/python/backtest.py
Node.js (napi-rs) npm install wickra examples/node/backtest.js
Browser / WASM npm install wickra-wasm examples/wasm/index.html
Rust cargo add wickra examples/rust/src/bin/backtest.rs

Each binding ships several runnable examples (streaming, backtest, live feed); examples/README.md is the full cross-language index.

The wickra-core crate is unsafe-forbidden, so every binding inherits a memory-safe implementation.

Rust API

use wickra::{Indicator, BatchExt, Chain, Ema, Rsi, Sma};

// Streaming or batch — same trait, same code.
let mut sma = Sma::new(14)?;
let out: Vec<Option<f64>> = sma.batch(&[1.0, 2.0, 3.0, 4.0, 5.0]);

let mut rsi = Rsi::new(14)?;
for price in live_feed {
    if let Some(v) = rsi.update(price) {
        println!("RSI = {v}");
    }
}

// Compose indicators: RSI(7) on top of EMA(14).
let mut chain = Chain::new(Ema::new(14)?, Rsi::new(7)?);
chain.update(price);

Live data sources

wickra-data (separate crate, opt-in) ships:

  • A streaming OHLCV CSV reader.
  • A tick-to-candle aggregator with arbitrary timeframes.
  • A candle resampler for multi-timeframe analysis (1m → 5m → 1h on the fly).
  • A Binance Spot WebSocket kline adapter (feature live-binance).
use wickra::{Indicator, Rsi};
use wickra_data::live::binance::{BinanceKlineStream, Interval};

let mut stream = BinanceKlineStream::connect(&["BTCUSDT".into()], Interval::OneMinute).await?;
let mut rsi = Rsi::new(14)?;
while let Some(event) = stream.next_event().await? {
    if event.is_closed {
        if let Some(v) = rsi.update(event.candle.close) {
            println!("RSI = {v:.2}");
        }
    }
}

A Python live-trading example using the public websockets package lives at examples/python/live_trading.py.

Project layout

wickra/
├── crates/
│   ├── wickra-core/         core engine + all 71 indicators
│   ├── wickra/              top-level facade crate (publishes on crates.io) + benches/
│   └── wickra-data/         CSV reader, tick aggregator, live exchange feeds
├── bindings/
│   ├── python/              PyO3 + maturin (publishes on PyPI)
│   ├── node/                napi-rs (publishes on npm)
│   └── wasm/                wasm-bindgen (browsers, bundlers, Node)
├── examples/                examples/README.md indexes every language
│   ├── data/                real BTCUSDT OHLCV datasets, one per timeframe
│   ├── rust/                Rust workspace member (`wickra-examples`)
│   ├── python/              backtest, live trading, parallel assets, multi-tf
│   ├── node/                streaming, backtest, live trading (load `wickra`)
│   └── wasm/                browser demo for `wickra-wasm`
└── .github/workflows/       CI and release pipelines

Rust benchmarks live in crates/wickra/benches/; runnable Rust examples live in the workspace member crate at examples/rust/. There is no top-level benches/ directory.

Building everything from source

# Rust core + tests
cargo test --workspace
cargo clippy --workspace --all-targets -- -D warnings
cargo bench -p wickra

# Python binding (requires Rust toolchain + maturin)
cd bindings/python
maturin develop --release
pytest

# WASM binding (requires wasm-pack + wasm32-unknown-unknown target)
wasm-pack build bindings/wasm --target web --release --features panic-hook

# Node binding (requires @napi-rs/cli)
cd bindings/node && npm install && npm run build && npm test

Testing

Every layer is covered; run the suites with the commands in Building everything from source.

  • wickra-core: unit tests per indicator — textbook reference values (Wilder RSI, Bollinger Bands, MACD, ATR, Stochastic), batch == streaming equivalence, reset semantics, NaN/Inf handling, and property tests.
  • wickra-data: unit tests for CSV decoding, the tick aggregator, the resampler, and the Binance payload parser.
  • bindings/python: pytest covering smoke checks, streaming/batch equivalence, reference values, lifecycle, input validation, and dict/tuple candle inputs.
  • bindings/node: node --test cases for batch, streaming, and reference values across all indicators.
  • bindings/wasm: wasm-bindgen-test cases for constructors, equivalence, and reference values.

Contributing

Contributions are very welcome — issues, bug reports, ideas, and pull requests all land in the same place: https://github.com/kingchenc/wickra.

A short orientation for first-time contributors:

  • Adding an indicator. Implement the Indicator trait in crates/wickra-core/src/indicators/<name>.rs, wire it into indicators/mod.rs and the crate root, and add reference-value tests, a batch == streaming equivalence test, and (where it makes sense) a proptest. The four bindings inherit your indicator automatically once you expose it in the language wrappers.
  • Fixing a numeric bug. Add a failing test that pins the textbook value first, then fix the math. Property tests in crates/wickra-core catch most regressions; please don't disable them.
  • Improving a binding. Each binding lives under bindings/<lang> with its own tests; please keep the batch == streaming invariant.
  • Style. cargo fmt --all + cargo clippy --workspace --all-targets -- -D warnings are CI gates; running them locally before pushing keeps reviews short.

For larger architectural changes, open an issue first so we can sketch the shape together before you invest the time.

License

Licensed under the PolyForm Noncommercial License 1.0.0. See LICENSE.

In plain English: use it, fork it, modify it, redistribute it, file issues, send pull requests — all welcome. Personal projects, research, education, non-profits, government, hobby trading bots: all fine. The one thing that's not allowed is commercial sale of the software or of services built around it. If you want to use Wickra commercially, get in touch about a license.


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If Wickra saved you time, the cheapest way to say thanks is to the repo.