Williams Fractal

Created by Larry Williams, Fractal is a retrospective price pattern that identifies a central high or low point chevron. [Discuss] 💬

// C# usage syntax
IReadOnlyList<FractalResult> results =
  bars.ToFractal(windowSpan);

Parameters

param	type	description
windowSpan	int	Evaluation window span width (S). Must be at least 2. Default is 2.
endType	EndType	Determines whether Close or High/Low are used to find end points. Default is EndType.HighLow.

The total evaluation window size is 2×S+1, representing ±S from the evaluation date.

Historical price bars requirements

You must have at least 2×S+1 periods of bars to cover the warmup periods; however, more is typically provided since this is a chartable candlestick pattern.

bars is a collection of generic TBar historical price bars. It should have a consistent frequency (day, hour, minute, etc). See the Guide for more information.

EndType enum options

enum	int	description
EndType.Close	0	Threshold measured from bar Close price
EndType.HighLow	1	Threshold measured from bar High and Low price

Response

IReadOnlyList<FractalResult>

• This method returns a time series of all available indicator values for the bars provided.
• It always returns the same number of elements as there are in the historical price bars.
• It does not return a single incremental indicator value.
• The first and last S periods in bars are unable to be calculated since there's not enough prior/following data.

️🖌️ Repaint warning

This price pattern uses future bars and will never identify a fractal in the last S periods of bars. Fractals are retroactively identified.

FractalResult

property	type	description
Timestamp	DateTime	Date from evaluated TBar
FractalBear	decimal	Value indicates a high point; otherwise null is returned.
FractalBull	decimal	Value indicates a low point; otherwise null is returned.

Utilities

• .Condense()
• .Find(lookupDate)
• .RemoveWarmupPeriods(removePeriods)

See Utilities and helpers for more information.

Chaining

This indicator is not chain-enabled and must be generated from bars. It cannot be used for further processing by other chain-enabled indicators.

See Chaining indicators for more.

Streaming

Use the buffer-style List<T> when you need incremental calculations without a hub:

FractalList fractalList = new(windowSpan);

foreach (IBar bar in bars)  // simulating stream
{
  fractalList.Add(bar);
}

// based on `ICollection<FractalResult>`
IReadOnlyList<FractalResult> results = fractalList;

Subscribe to a BarHub for advanced streaming scenarios:

BarHub barHub = new();
FractalHub observer = barHub.ToFractalHub(windowSpan);

foreach (IBar bar in bars)  // simulating stream
{
  barHub.Add(bar);
}

IReadOnlyList<FractalResult> results = observer.Results;

See Buffer lists and Stream hubs for full usage guides.