StochasticClose — Stochastic Close

Where the current close sits inside the last N closes, on a 0–100 scale. A close-only stochastic: it uses the highest and lowest close, not the highest high and lowest low.

StochasticClose is the identifier a strategy writes; Stochastic Close is the label the chart’s indicator picker shows. Single value — .value is the only accessor.

Signature

StochasticClose(period, on=<source>)

Argument	Type	Required	Notes
period	int Param or literal	Yes	Lookback window. Default 14, bounds 5–100.
on=	symbol, OHLCV field, or indicator	No	Source. Defaults to the trade symbol’s close.

Formula

Over the last N values of the source:

$$ \text{StochasticClose} = \frac{\text{close}_t - \min}{\max(\max - \min,\ 0.0001)} \times 100 $$

0 means the current close is the lowest of the window, 100 means it is the highest, 50 means it sits mid-range. The denominator is floored at a small epsilon so a dead-flat window cannot divide by zero.

Warmup

period bars. Before the window fills, the indicator returns 50 — the neutral midpoint, not 0. A strategy never observes it (execute() is suppressed until every indicator is ready), but it is what the chart plots on the leading bars.

Reading the value

stoch.value               # 0..100
stoch.value_at(1)
stoch < 20                # oversold
stoch > 80                # overbought
stoch.crossed_above(20)   # the bar it leaves oversold

Example

class StochasticDip(Strategy):
    """Buy the exit from oversold, sell back into the top of the range."""
    period = Param(14, min=5, max=100)
    trade = Symbol()
    sizing = FixedCapital()

    def execute(self):
        stoch = StochasticClose(self.period, on=self.trade)
        self.stop_loss(3.0)

        if stoch.crossed_above(20) and self.trade.is_flat:
            self.buy(self.trade, reason=f"Leaving oversold ({stoch.value:.0f})")

        if stoch.value > 80 and self.trade.is_long:
            self.sell(self.trade, self.trade.position, reason="Top of the range")

Notes

• A perfectly flat window reads 0, not 50. When every close in the window is identical, the numerator is zero and the epsilon-floored denominator keeps the division finite — so the indicator reports “at the bottom of the range” for a market that has no range at all. On thinly-traded or halted instruments, filter those bars out rather than trusting the read.
• Close-only by design. The classic %K uses the window’s highest high and lowest low; this one uses closes on both ends, so it is smoother and never reacts to a wick.
• Bounded 0–100, which makes it directly comparable across instruments — unlike MADeviation or PriceChannelWidth.
• There is no built-in %D smoothing line. Chain one yourself: EMA(3, on=stoch).
• WilliamsClose is the same measurement on a −100–0 scale.