BullishPercentIndex

The Bullish Percent Index (BPI) — the percentage of symbols in a universe on a point-and-figure buy signal. A bounded 0..=100 gauge of how many issues are in a confirmed uptrend.

Quick reference

Item	Value
Family	Market Breadth
Input type	CrossSection — the per-symbol state of the whole universe
Output type	f64 (a percentage in 0..=100)
Output range	0..=100
Default parameters	none
Warmup period	1
Interpretation	Confirmed-uptrend participation

Formula

bpi = 100 * on_buy_signal_count / universe_size   # per tick

where on_buy_signal_count is the number of members whose on_buy_signal flag is set (the caller evaluates each symbol's point-and-figure chart when it builds the tick). The universe is non-empty by construction, so the share is always defined. Stateless per tick and O(universe size). See crates/wickra-core/src/indicators/bullish_percent_index.rs.

Parameters

None. Construct with BullishPercentIndex::new(). (The point-and-figure box/reversal settings live in the caller-supplied on_buy_signal flag.)

Parameter	Type	Default	Source
—	—	—	None.

Inputs / Outputs

Indicator<Input = CrossSection, Output = f64>:

use wickra::{BullishPercentIndex, CrossSection, Indicator};

const _: fn(&mut BullishPercentIndex, CrossSection) -> Option<f64> =
    <BullishPercentIndex as Indicator>::update;

This indicator reads the per-symbol on_buy_signal flag, which is not part of the core four signals — so its bindings take a fifth array (on_buy_signal). Build the members with Member::with_signals(change, volume, new_high, new_low, above_ma, on_buy_signal).

• Python: update(change, volume, new_high, new_low, on_buy_signal); batch(...) takes five array groups per tick and returns a 1-D ndarray.
• Node: update(change, volume, newHigh, newLow, onBuySignal); batch returns number[].
• WASM: update(change, volume, newHigh, newLow, onBuySignal) only; every array is numeric (non-zero is true).

Warmup

warmup_period() == 1; defined from the first tick (tests accessors_and_metadata, first_tick_emits_percentage).

Edge cases

• All / none bullish. Returns 100.0 / 0.0 (tests all_bullish_is_one_hundred, none_bullish_is_zero).
• Reset. reset() returns the indicator to not-ready (test reset_clears_state).
• Invalid / empty universe. Rejected at construction by CrossSection::new.
• Ragged arrays. The bindings reject a tick whose on_buy_signal array length differs from the others.

Examples

Rust

use wickra::{BullishPercentIndex, CrossSection, Indicator, Member};

let mut bpi = BullishPercentIndex::new();
// 2 of 4 symbols on a buy signal -> 50%.
let tick = CrossSection::new(
    vec![
        Member::with_signals(1.0, 10.0, false, false, false, true),
        Member::with_signals(1.0, 10.0, false, false, false, true),
        Member::with_signals(-1.0, 10.0, false, false, false, false),
        Member::with_signals(-1.0, 10.0, false, false, false, false),
    ],
    0,
)?;
assert_eq!(bpi.update(tick), Some(50.0));

Python

import wickra as ta

bpi = ta.BullishPercentIndex()
# fifth array is the per-symbol point-and-figure buy-signal flag.
print(bpi.update([1.0, 1.0, -1.0, -1.0], [10.0] * 4, [False] * 4, [False] * 4, [True, True, False, False]))
# 50.0

Node

const { BullishPercentIndex } = require('wickra');

const bpi = new BullishPercentIndex();
const flags = [false, false, false, false];
console.log(
  bpi.update([1, 1, -1, -1], [10, 10, 10, 10], flags, flags, [true, true, false, false]),
);
// 50

Streaming

import wickra as ta

bpi = ta.BullishPercentIndex()
flags = [False] * 4
vol = [10.0] * 4
print(bpi.update([1.0, 1.0, -1.0, -1.0], vol, flags, flags, [True, True, False, False]))  # 50.0
print(bpi.update([1.0, 1.0, 1.0, 1.0], vol, flags, flags, [True, True, True, True]))       # 100.0

Interpretation

The BPI is a classic point-and-figure breadth gauge with well-defined zones.

1. Above 70. Overbought — broad strength, but a crowded market vulnerable to a reversal.
2. Below 30. Oversold — broad weakness, a washout candidate.
3. Reversals from the zones. A turn down from above 70 or up from below 30 (the index reversing into a new P&F column) is the classic BPI sell / buy trigger.

Common pitfalls

• Caller defines the signal. This indicator does not build point-and-figure charts; it counts the on_buy_signal flag you supply, so keep the box size and reversal amount consistent.
• Fifth array. Like PercentAboveMa, the bindings require the extra on_buy_signal array — a four-array call will not type-check.
• Universe must be stable. Changing membership makes the percentages incomparable.

References

• Cohen, A. W. — point-and-figure charting and the Bullish Percent Index (popularised by Dorsey, T. J., Point and Figure Charting).

See also

• Indicator-PercentAboveMa — the moving-average participation analogue.
• Indicators-Overview — the full taxonomy.