Hammer (CDLHAMMER)

Summary

Single-candle pattern: a small real body at the top of the range with a long lower shadow and little or no upper shadow, sitting at or near the prior candle's low. A hit flags a potential bullish reversal.

Notes

Does not verify the preceding downtrend that the pattern classically assumes; confirm the trend context yourself.
Bulkowski's testing found the Hammer reverses a preceding downtrend about 60% of the time — in his words "not far from random (50%)" — and it ranks a modest 65th of 103 patterns for post-breakout performance. (thepatternsite.com)

Inputs

inOpen — Open price of each bar
inHigh — High price of each bar
inLow — Low price of each bar
inClose — Close price of each bar

Outputs

outInteger — +100 when the hammer is detected, 0 otherwise. Bullish only; never emits -100

Output Values

Value	Meaning
0	No pattern
100	Hammer detected — a bullish reversal signal that classically assumes a preceding downtrend, unverified by the function

Properties

Numerical Stability: Start-Independent


☐ Overlap Input
✅ Independent Y-Axis i
✅ Candlestick i
☐ Can Output NaN or ±Inf
☐ Identity at Period 1

Implementation

TA-Lib Definition: cdlhammer.c · cdlhammer.yaml

Native	File
C	`ta_CDLHAMMER.c`
Rust	`cdlhammer.rs`
Java	`Core_CDLHAMMER.java`

TA-Lib is also available for Python, R and more using a wrapper.

Aliases

Hammer