StreamingLowess API

When to Use

Dataset >100,000 points
Memory-constrained environments
Batch processing pipelines

Class

`StreamingLowess`

The StreamingLowess class processes data in chunks, suitable for very large datasets or streaming applications.

Constructor:

const { StreamingLowess } = require('fastlowess-wasm');

const stream = new StreamingLowess({ fraction: 0.5 }, { chunk_size: 50, overlap: 10 });
console.log("typeof process_chunk:", typeof stream.process_chunk);

typeof process_chunk: function

options: An object containing LowessOptions fields.
streamingOptions: An object containing StreamingOptions fields.

Methods:

const { StreamingLowess } = require('fastlowess-wasm');

const n = 100;
const x = Float64Array.from({ length: n }, (_, i) => i * 2 * Math.PI / (n - 1));
const y = Float64Array.from(x, xi => Math.sin(xi) + 0.1);

const stream = new StreamingLowess({ fraction: 0.5 }, { chunk_size: 50, overlap: 10 });
const partialResult = stream.process_chunk(x.slice(0, 50), y.slice(0, 50));
console.log("Fraction used:", partialResult.fraction_used);

Fraction used: 0.5

Processes a chunk of data. Returns partial results.

const { StreamingLowess } = require('fastlowess-wasm');

const n = 100;
const x = Float64Array.from({ length: n }, (_, i) => i * 2 * Math.PI / (n - 1));
const y = Float64Array.from(x, xi => Math.sin(xi) + 0.1);

const stream = new StreamingLowess({ fraction: 0.5 }, { chunk_size: 50, overlap: 10 });
stream.process_chunk(x.slice(0, 50), y.slice(0, 50));
stream.process_chunk(x.slice(50), y.slice(50));
const finalResult = stream.finalize();
console.log("Fraction used:", finalResult.fraction_used);

Fraction used: 0.5

Finalizes the smoothing process and returns any remaining buffered results.

Result Structure

`LowessResult`

Returned by process_chunk() and finalize().

Field	Type	Description
`x`	`Float64Array`	Sorted x values
`y`	`Float64Array`	Smoothed y values
`fraction_used`	`number`	Fraction used
`iterations_used`	`number \| undefined`	Robustness iterations actually performed
`residuals`	`Float64Array \| undefined`	Residuals (if `return_residuals`)
`robustness_weights`	`Float64Array \| undefined`	Robustness weights (if `return_robustness_weights`)
`diagnostics`	`Diagnostics \| undefined`	Fit metrics (if `return_diagnostics`)
`dimensions`	`number`	Number of predictor dimensions

See wasm.md for the full LowessResult field reference.

Options Structure

`StreamingOptions` (inherits `LowessOptions`)

Field	Type	Default	Description
`chunk_size`	`number`	`5000`	Data chunk size
`overlap`	`number`	`500`	Overlap between chunks
`merge_strategy`	`string`	`"weighted_average"`	Strategy for blending overlap regions

Options

merge_strategy

See: Merge Strategies

Strategy	Alias	Behavior
`"weighted_average"` (default)	`"weighted"`	Distance-weighted blend
`"average"`	`"mean"`	Average overlapping values
`"take_first"`	`"first"`	Keep left chunk values
`"take_last"`	`"last"`	Keep right chunk values

Merge Strategies