Implementation:TA Lib Ta lib python CDL Function API

Knowledge Sources	ta-lib-python TA-Lib C Library
Domains	Technical_Analysis, Pattern_Recognition
Last Updated	2026-02-09 22:00 GMT

Overview

Concrete tool for detecting candlestick patterns via 61 CDL* functions (CDLDOJI, CDLENGULFING, CDLMORNINGSTAR, etc.) provided by the TA-Lib Cython bindings.

Description

The 61 CDL (candlestick) functions are Cython wrappers around the TA-Lib C library's pattern recognition routines. Each function takes four OHLC arrays and returns an integer array where non-zero values indicate pattern detection.

Representative functions:

CDLDOJI — Doji pattern (single candle, no parameters)
CDLENGULFING — Engulfing pattern (two candles, no parameters)
CDLMORNINGSTAR — Morning Star (three candles, penetration parameter)

Usage

Call any CDL function with four OHLC arrays. Check output for non-zero values to find pattern occurrences.

Code Reference

Source Location

Repository: ta-lib-python
File: talib/_func.pxi
Lines: L1252-1280 (CDLDOJI), L1348-1376 (CDLENGULFING), L2156-2186 (CDLMORNINGSTAR)

Signature

def CDLDOJI(open: np.ndarray, high: np.ndarray,
            low: np.ndarray, close: np.ndarray) -> np.ndarray:
    """Doji pattern. Returns int32 array: -100, 0, or +100."""

def CDLENGULFING(open: np.ndarray, high: np.ndarray,
                 low: np.ndarray, close: np.ndarray) -> np.ndarray:
    """Engulfing pattern. Returns int32 array: -100, 0, or +100."""

def CDLMORNINGSTAR(open: np.ndarray, high: np.ndarray,
                   low: np.ndarray, close: np.ndarray,
                   penetration: float = 0.3) -> np.ndarray:
    """Morning Star pattern with configurable penetration threshold."""

Import

import talib

I/O Contract

Inputs

Name	Type	Required	Description
open	np.ndarray (float64)	Yes	Opening prices
high	np.ndarray (float64)	Yes	High prices
low	np.ndarray (float64)	Yes	Low prices
close	np.ndarray (float64)	Yes	Closing prices
penetration	float	No	Threshold for some patterns (e.g., CDLMORNINGSTAR default 0.3)

Outputs

Name	Type	Description
pattern_signal	np.ndarray (int32)	Array of same length as input: -100 (bearish), 0 (no pattern), +100 (bullish)

Usage Examples

Detect Doji Patterns

import numpy as np
import talib

# Generate sample OHLC data
n = 100
close = np.cumsum(np.random.randn(n) * 0.5) + 100
open_p = close + np.random.randn(n) * 0.01  # Near-equal open/close for doji
high = np.maximum(open_p, close) + np.abs(np.random.randn(n) * 0.5)
low = np.minimum(open_p, close) - np.abs(np.random.randn(n) * 0.5)

doji = talib.CDLDOJI(open_p, high, low, close)
doji_indices = np.where(doji != 0)[0]
print(f"Doji patterns found at indices: {doji_indices}")

Detect Engulfing Patterns

engulfing = talib.CDLENGULFING(open_p, high, low, close)
bullish = np.where(engulfing == 100)[0]
bearish = np.where(engulfing == -100)[0]
print(f"Bullish engulfing at: {bullish}")
print(f"Bearish engulfing at: {bearish}")

Related Pages

Implements Principle

Principle:TA_Lib_Ta_lib_python_Candlestick_Pattern_Detection

Requires Environment

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