BeltHold — Belt Hold

A long body that opened at its own extreme and never traded back through it — bullish opens at the low, bearish at the high. The session’s direction was set at the bell.

Signature

BeltHold(lookback, body_ratio, shadow_ratio, on=<source>)

Argument	Type	Required	Notes
lookback	int Param	Yes	Pinned at 1. Bounds 1–1.
body_ratio	float Param or literal	Yes	Minimum body as a fraction of the range. Default 0.7, bounds 0.3–1.0.
shadow_ratio	float Param or literal	Yes	Largest shadow on the opening side, as a fraction of the range. Default 0.05, bounds 0.0–0.3.
on=	symbol	No	Source symbol. Defaults to the trade symbol. Reads open, high, low, close.

Formula

A long body with no shadow on the side it opened from; +1 when white, −1 when black.

Warmup

None.

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

    def execute(self):
        p = BeltHold(1, 0.7, 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="Bullish belt hold")
        if self.trade.is_long and self.trade.close < sma.value:
            self.sell(self.trade, self.trade.position, reason="Trend lost")

Notes

• A marubozu with only one clean end; strictly weaker, and it fires more often.