FryPanBottom

A gently rounded (U-shaped) base confirmed by recovery above the rim — a bullish accumulation pattern.

Quick reference

Field	Value
Family	Candlestick Patterns
Input type	Candle (close)
Output type	f64
Output range	{0, +1}
Default parameters	(period = 9) (Python)
Warmup period	period
Interpretation	+1 rounded bottom breakout.

Formula

over the last `period` closes:
  the minimum close sits in the middle (index in [period/4, 3·period/4))  -> a bowl
  latest close > first close  AND  latest close > minimum close            -> recovery
signal = +1 when both hold, else 0

The frying pan is a saucer base: selling dries up, the curve flattens, and price lifts off the rim. The pattern requires a central low (a symmetric bowl, not a one-sided drop) and a close back above the window's opening level. Source: crates/wickra-core/src/indicators/fry_pan_bottom.rs.

Parameters

Name	Type	Default	Valid range	Source	Description
period	usize	9 (Python)	>= 5	fry_pan_bottom.rs:53	Window length of the rounded base. < 5 errors with Error::InvalidPeriod.

The period getter returns the window; value returns the current output if ready.

Inputs / Outputs

From crates/wickra-core/src/indicators/fry_pan_bottom.rs:

use wickra::{Candle, Indicator, FryPanBottom};
// FryPanBottom: Input = Candle, Output = f64
const _: fn(&mut FryPanBottom, Candle) -> Option<f64> = <FryPanBottom as Indicator>::update;

A Candle in, an Option<f64> out (+1/0). Python update(candle) / batch(close); Node update(close) / batch(close[]).

Warmup

warmup_period() == period. The window must fill first (first_emission_at_warmup_period pins this).

Edge cases

• Rounded bottom → +1. A U-base then recovery signals (rounded_bottom_then_recovery_signals pins this).
• One-sided drop → 0. A straight decline is not a bowl (one_sided_drop_is_zero pins this).
• No recovery → 0. A bowl that never reclaims the rim does not signal (no_recovery_is_zero pins this).
• Finiteness. Candle::new rejects non-finite fields, so no in-method guard is needed.
• Reset. f.reset() clears the close window and the last value (reset_clears_state).

Examples

Rust

use wickra::{BatchExt, Candle, Indicator, FryPanBottom};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut f = FryPanBottom::new(9)?;
    let closes = [100.0, 98.0, 96.0, 95.0, 96.0, 98.0, 101.0, 103.0, 105.0];
    let candles: Vec<Candle> = closes.iter().map(|&x| Candle::new(x, x+0.5, x-0.5, x, 1_000.0, 0).unwrap()).collect();
    println!("{:?}", f.batch(&candles).last().unwrap()); // Some(1.0)
    Ok(())
}

Output:

Some(1.0)

Python

import numpy as np
import wickra as ta

f = ta.FryPanBottom(9)
close = np.array([100, 98, 96, 95, 96, 98, 101, 103, 105], float)
print(f.batch(close)[-1])  # 1.0

Node

const ta = require('wickra');
const f = new ta.FryPanBottom(9);
console.log(f.batch([100, 98, 96, 95, 96, 98, 101, 103, 105]).at(-1)); // 1

Streaming

use wickra::{Candle, Indicator, FryPanBottom};

let mut f = FryPanBottom::new(9).unwrap();
let feed: Vec<Candle> = Vec::new(); // your live stream
for candle in feed {
    if f.update(candle) == Some(1.0) { println!("frying pan bottom"); }
}

Streaming update and batch are equivalent tick-for-tick (batch_equals_streaming pins this).

Interpretation

1. Accumulation base. The rounded shape signals patient accumulation; the breakout off the rim is the entry.
2. Volume confirmation. A genuine frying pan often shows volume rising into the right side of the bowl — confirm with a volume indicator.
3. Target. A common target projects the depth of the bowl above the breakout.

Common pitfalls

• Window sizing. Too short a period calls every dip a pan; too long misses compact bases.
• Close-only. It uses closes; intrabar spikes are ignored.
• Bullish only. For the rounded top see DumplingTop.

References

Bulkowski, T. N. (2005), Encyclopedia of Chart Patterns (rounded bottoms); a Japanese candlestick equivalent appears in Nison, S. (1994), Beyond Candlesticks.

See also

• Indicator-DumplingTop — the rounded-top mirror.
• Indicator-CupAndHandle — cup base with handle.
• Indicator-DoubleTopBottom — double-extreme reversal.
• Indicators-Overview — the full taxonomy.