# Similarity Search

A Node.js module that performs word order independent similarity search on strings.

This module is built as a native addon that uses C code for fast similarity computations. It uses Jaccard similarity between word sets to find matches regardless of word order.

## Installation

```bash
npm install
```

## Usage

```javascript
const SimilaritySearch = require('./index');

// Create a new search index with default capacity (500)
const index = new SimilaritySearch();

// Add strings to the index
index.addString('bio bizz');
index.addString('lightmix bizz btio substrate');
index.addString('bizz bio mix light');

// Add multiple strings at once
index.addStrings([
  'plant growth bio formula',
  'garden soil substrate'
]);

// Search the index with a query and similarity cutoff
const results = index.search('bio bizz', 0.2);

// Display results
results.forEach(match => {
  console.log(`${match.similarity.toFixed(2)}: ${match.string}`);
});
```

## API

### `new SimilaritySearch([capacity])`

Creates a new search index.

- `capacity` (optional): Initial capacity for the index. Default: 500.

### `addString(str)`

Adds a string to the index.

- `str`: The string to add.
- Returns: Boolean indicating success.

### `addStrings(strings)`

Adds multiple strings to the index.

- `strings`: Array of strings to add.
- Returns: Boolean indicating if all adds were successful.

### `search(query, [cutoff])`

Searches the index for strings similar to the query.

- `query`: The search query.
- `cutoff` (optional): Similarity threshold between 0.0 and 1.0. Default: 0.2.
- Returns: Array of matching results, sorted by similarity (descending).

### `size()`

Gets the number of strings in the index.

- Returns: Number of strings in the index.

## Helper Functions

### `SimilaritySearch.createTestIndex([size])`

Creates a test index with random data.

- `size` (optional): Number of strings to generate. Default: 500.
- Returns: A new SimilaritySearch instance with random data.

### `SimilaritySearch.benchmark(index, queries, [cutoff])`

Benchmarks the search performance.

- `index`: The index to benchmark.
- `queries`: Array of search queries.
- `cutoff` (optional): Similarity threshold. Default: 0.2.
- Returns: Benchmark results.

## How It Works

The similarity search uses Jaccard similarity between word sets:

```
similarity = (number of matching words) / (total unique words)
```

This means word order doesn't matter - "bio bizz" will match with "bizz bio" with 100% similarity.

## Building

To rebuild the native addon:

```bash
npm install
```

## Testing

Run the test script:

```bash
npm test
```