Doji

A bar whose body is negligible against its range: buyers and sellers finished level. On its own it is indecision, not a signal — its meaning comes entirely from where it appears.

Signature

Doji(lookback, body_ratio, on=<source>)

Argument	Type	Required	Notes
lookback	int Param	Yes	Pinned at 1; the recogniser needs no window. Bounds 1–1.
body_ratio	float Param or literal	Yes	Largest body, as a fraction of the range, still counted as a doji. Default 0.05, bounds 0.001–0.5.
on=	symbol	No	Source symbol. Defaults to the trade symbol. Reads open, high, low, close.

Formula

$$ \text{Doji} = 1 \text{ when } \frac{|C - O|}{H - L} \le \text{body ratio} $$

Warmup

None. A zero-range bar returns 0.

Reading the value

p.value
p > 0

Pattern indicators return a flag, not a level: +1 bullish, -1 bearish, 0 absent. They are zero on most bars by design, so treat them as event triggers rather than as something to smooth or cross.

Example

class DojiPause(Strategy):
    """Act on the pattern only in the direction of the longer trend."""
    trade = Symbol()
    sizing = FixedCapital()

    def execute(self):
        p = Doji(1, 0.05, on=self.trade)
        sma = SMA(50, on=self.trade)
        if p.value > 0 and self.trade.close > sma.value and self.trade.is_flat:
            self.buy(self.trade, reason="Doji in an uptrend")
        if self.trade.is_long and self.trade.close < sma.value:
            self.sell(self.trade, self.trade.position, reason="Trend lost")

Notes

• The classic single-bar candle. body_ratio is the whole definition — TA-Lib compares the body against a rolling average range instead; here it is an explicit, sweepable fraction.