 # compute-hamming

Computes the Hamming distance between two sequences.

## Stats

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compute-hamming
1001.1.08 years ago9 years ago Hamming Distance
!NPM versionnpm-imagenpm-url !Build Statustravis-imagetravis-url !Coverage Statuscoveralls-imagecoveralls-url !Dependenciesdependencies-imagedependencies-url
Computes the Hamming distance between two sequences.

In information theory, the Hamming distance is number of differences between two sequences of the same length. These sequences may be represented as character strings, binary strings, or arrays.

## Installation

``\$ npm install compute-hamming``

For use in the browser, use browserify.

## Usage

``var hamming = require( 'compute-hamming' );``

#### hamming( a, b, accessor )

Computes the Hamming distance between two sequences. The sequences must be either both equal length `strings` or equal length `arrays`.
``````var a = 'this is a string.',
b = 'thiz iz a string.';

var dist = hamming( a, b );
// returns 2

var c = [ 5, 23, 2, 5, 9 ],
d = [ 3, 21, 2, 5, 14 ];

dist = hamming( c, d );
// returns 3``````

To compute the Hamming distance between nested `array` values, provide an accessor `function` for accessing `array` values.
``````var a = [
{'x':2},
{'x':4},
{'x':5},
{'x':3},
{'x':8},
{'x':2}
];

var b = [
[1,3],
[2,1],
[3,5],
[4,3],
[5,7],
[6,2]
];

function getValue( d, i, j ) {
if ( j === 0 ) {
return d.x;
}
return d[ 1 ];
}

var dist = hamming( a, b, getValue );
// returns 3``````

The accessor `function` is provided three arguments:
• d: current datum.
• i: current datum index.
• j: sequence index; e.g., sequence `a` has index `0` and sequence `b` has index `1`.

## Examples

To run the example code from the top-level application directory,
``\$ node ./examples/index.js``

## Tests

### Unit

Unit tests use the Mocha test framework with Chai assertions. To run the tests, execute the following command in the top-level application directory:
``\$ make test``

All new feature development should have corresponding unit tests to validate correct functionality.

### Test Coverage

This repository uses Istanbul as its code coverage tool. To generate a test coverage report, execute the following command in the top-level application directory:
``\$ make test-cov``

Istanbul creates a `./reports/coverage` directory. To access an HTML version of the report,
``\$ make view-cov``