Inverted Hammer

Single-bar bullish reversal candidate. The mirror of a Hammer: small real body near the bottom of the bar, a long upper shadow at least twice the body, and a short or absent lower shadow. Read as a failed test of upper resistance that may foreshadow a bullish reversal.

Quick reference

Item	Value
Family	Candlestick Patterns
Input type	Candle
Output type	f64 — +1.0 if Inverted Hammer, 0.0 otherwise
Output range	{0.0, +1.0}
Default parameters	none — InvertedHammer::new()
Warmup period	1
Interpretation	Bullish reversal candidate (in downtrend context)

Formula

body         = |close - open|
upper_shadow = high - max(open, close)
lower_shadow = min(open, close) - low

inverted = (upper_shadow >= 2 · body)
        AND (lower_shadow <= body)
        AND (body > 0)

Output is +1.0 when the shape matches, 0.0 otherwise. See crates/wickra-core/src/indicators/inverted_hammer.rs.

Parameters

None — InvertedHammer::new() takes no arguments. Shape ratios are fixed.

Signed ±1 encoding

An Inverted Hammer is bullish by definition, so under the uniform candlestick sign convention (+1.0 bullish, −1.0 bearish, 0.0 none) it emits +1.0 when the shape matches and 0.0 otherwise — never −1.0. The same geometry read at the top of an uptrend is the bearish ShootingStar, which carries the opposite sign.

Inputs / Outputs

Indicator<Input = Candle, Output = f64>. Python / Node: same shape as Hammer.

Warmup

warmup_period() == 1. Stateless.

Edge cases

• Zero-body bar. Pure Doji is not an Inverted Hammer.
• No trend filter. Shape only — combine with a trend indicator for actionable signals.
• Reset. Stateless.

Examples

Rust

use wickra::{Candle, Indicator, InvertedHammer};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Inverted Hammer: o=100.5, h=105, l=100, c=100  — long upper shadow
    let c = Candle::new(100.5, 105.0, 100.0, 100.2, 1.0, 0)?;
    let mut ih = InvertedHammer::new();
    println!("{:?}", ih.update(c));
    Ok(())
}

Python

import numpy as np
import wickra as ta

o = np.array([100.5])
h = np.array([105.0])
l = np.array([100.0])
c = np.array([100.2])

ih = ta.InvertedHammer()
print(ih.batch(o, h, l, c))

Node

const wickra = require('wickra');
const ih = new wickra.InvertedHammer();
console.log(ih.batch([100.5], [105], [100], [100.2]));

Streaming

use wickra::{Candle, Indicator, InvertedHammer};

let mut ih = InvertedHammer::new();
let candle_stream: Vec<wickra::Candle> = Vec::new(); // your live OHLCV candle feed
for bar in candle_stream {
    if ih.update(bar) == Some(1.0) {
        /* inverted hammer — combine with downtrend filter */
    }
}

Interpretation

• Bullish reversal candidate. Most powerful at the bottom of a downtrend. Buyers tried to push price up; sellers pushed back, but the failed attempt itself often signals exhaustion.
• Vs Hammer. Hammer: long lower shadow. Inverted Hammer: long upper shadow. Both bullish reversal candidates in downtrend context but different price-action stories.
• Vs Shooting Star. Identical shape; Inverted Hammer is the bullish reading (after downtrend), Shooting Star is the bearish reading (after uptrend). Context determines interpretation.

Common pitfalls

• Confusing with Shooting Star. Same shape, opposite trend context. See ShootingStar.
• Treating shape alone as actionable. Without downtrend context, an Inverted Hammer is just a candle.

References

• Steve Nison, Japanese Candlestick Charting Techniques (1991).

See also

• Hammer — long lower shadow variant.
• ShootingStar — same shape, bearish reading.
• HangingMan — Hammer's bearish twin.
• Indicators-Overview — full taxonomy.