sorted-merge-stream

Merge two sorted streams.

npm install sorted-merge-stream

Shamelessly taken from sorted-union-stream with slight modifications, where values with repeated key are also emitted.

merge(streamA, streamB, [toKey], [options])

Merge two lexicographically sorted streams.

• By default keys are mapped by value.key or value itself.
• Add a toKey function if you need custom key mapping.
• Use options.reverse = true for reverse order.

var merge = require('sorted-merge-stream')

var from = require('from2')
var a = from.obj(['a', 'b', 'd', 'e', 'g', 'h'])
var b = from.obj(['b', 'c', 'f'])

var stream = merge(a, b)

stream.pipe(...)

// 'a', 'b', 'b', 'c', 'd', 'e', 'f', 'g', 'h'

Merging multiple streams, custom key mapping, reverse order:

var merge = require('sorted-merge-stream')

var from = require('from2')
var a = from.obj([{id: 6}, {id: 3}, {id: 1}])
var b = from.obj([{id: 6}, {id: 2}, {id: 1}])
var c = from.obj([{id: 6}, {id: 5}, {id: 3}])

function toKey (data) {
  return data.id
}

var stream = [a, b, c].reduce(function (a, b) {
  return merge(a, b, toKey, {reverse: true})
})

stream.pipe(...)

// {id: 6}, {id: 6}, {id: 6}, {id: 5}, {id: 3}, {id: 3}, {id: 2}, {id: 1}, {id: 1}

License

MIT