cmm-stream

##cmm-stream

A stream-based Count-mean-min sketch implementation. Pipe in some strings/buffers to get frequency estimation.

var c = new Cmm(20, 20);

//...

myDataSource.pipe(c);

c.on('finish', function() {
  console.log(c.frequency('42'));
  console.log(c.frequency('13'));
});

API

Cmm(width, depth, hashType, streamOpts)

Construct a new writable Cmm (extends Stream.Writable).

• width - the width of the table. Higher values reduce the magnitude of the frequency error (default 10).
• depth - the depth of the table. Higher values reduce the probability of large frequency error (default 10).
• seed - the seed integer for the hash functions (default 42).
• hashType - which hashing algorithm to use on the values. Can be 'murmur' or any algorithm supported by crypto.createHash (default: 'murmur').
• streamOpts - the options to pass along to the stream constructor.

Cmm.frequency(value)

Compute the approximate frequency of value.

Cmm.export()

Export the Cmm data. Returns an object like:

{
  width: 10,
  depth: 10,
  seed: 42,
  hashType: 'whirlpool',
  total: 100000,
  registers: [...]
}

Cmm.import(data)

Import a Cmm data object. Replaces existing data.

Cmm.merge(cmm)

Merge this Cmm with another Cmm, creating a new instance. width, depth, seed, and hashType must match between the two.