InsideBar — Inside Bar

A bar whose entire range sits inside the previous bar’s: a contraction, and the setup half of most breakout rules. Returns 1 when present, 0 otherwise.

Signature

InsideBar(lookback, on=<source>)

Argument	Type	Required	Notes
lookback	int Param	Yes	Pinned at 1; the previous bar is kept in state. Bounds 1–1.
on=	symbol	No	Source symbol. Defaults to the trade symbol. Reads high and low.

Formula

$$ \text{InsideBar} = 1 \text{ when } H_t \le H_{t-1} \text{ and } L_t \ge L_{t-1} $$

Warmup

One bar of state.

Reading the value

ib.value
ib > 0

A flag, not a level: 1 present, 0 absent.

Example

class InsideBarBreakout(Strategy):
    """Buy the break of an inside bar's parent range."""
    trade = Symbol()
    sizing = FixedCapital()

    def execute(self):
        ib = InsideBar(1, on=self.trade)
        dh = DonchianHighTrue(2, on=self.trade)
        if ib.value_at(1) > 0 and self.trade.close > dh.value_at(1) and self.trade.is_flat:
            self.buy(self.trade, reason="Inside bar break")
        if self.trade.close < dh.value * 0.98 and self.trade.is_long:
            self.sell(self.trade, self.trade.position, reason="Break failed")

Notes

• Uses <= and >=, so a bar with an identical range to its predecessor counts as inside.
• Proven by an assert-via-trade run on SPY daily (matched a strategy-side reference exactly on every bar; zero alarm trades).