@jacobbubu/pull-window
v1.0.2
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@jacobbubu/pull-window
Rewritten pull-window in TypeScript.
Aggregate a pull-stream into windows.
Several helpers are provided for particular types of windows, sliding, tumbling, etc.
And also, a low level.
Example: "tumbling" window
sum every 10 items.
import * as pull from 'pull-stream'
import { window } from '@jacobbubu/pull-window'
function everyTen () {
let i = 0
//window calls init with each data item,
//and a callback to close that window.
return window(function (data, cb) {
//if you don't want to start a window here,
//return undefined
if(i !== 0) return
let sum = 0
//else return a function.
//this will be called all data
//until you callback.
return function (end, data) {
if(end) return cb(null, sum)
sum += data
if(++i >= 10) {
i = 0
cb(null, sum)
}
}
}
}
pull(
pull.count(1000),
everyTen(),
pull.log()
)
Example: variable sized window
Each window doesn't have to be the same size...
import * as pull from 'pull-stream'
import { window } from '@jacobbubu/pull-window'
function groupTo100 () {
let sum = null
return window(function (_, cb) {
if(sum !== null) return
/* sum stuff together until you have 100 or more*/
return function (end, data) {
if(end) return cb(null, sum)
sum += data
if(sum >= 100) {
// copy sum like this, incase the next item
// comes through sync
const _sum = sum
sum = null
cb(null, _sum)
}
}
})
}
pull(
pull.count(1000)
groupTo100(),
pull.log()
)
Example: sliding window
to make more over lapping windows just return the window function more often.
import * as pull from 'pull-stream'
import { window } from '@jacobbubu/pull-window'
function sliding () {
return window(function (_, cb) {
let sum = 0
let i = 0
/* sum stuff together until you have 100 or more*/
return function (end, data) {
if(end) return cb(null, sum)
sum += data
if(++i >= 10) {
//in this example, each window gets it's own sum,
//so we don't need to copy it.
cb(null, sum)
}
}
})
}
pull(
pull.count(100)
sliding(),
pull.log()
)
API
window (start, map)
window(function startWindow (data, cb) {
//called on each chunk
//including the first one
return function addToWindow (end, data) {
//cb(null, aggregate) when done.
}
}, function mapWindow (start, data) {
//(optional)
//map the window to something that tracks start, also
})
By default, windows are mapped to {start: firstData, data: aggregate}
.
unless you pass in an different mapWindow
function.
window.sliding(reduce, size)
reduce every size
items into a single value, in a sliding window
window.recent(size, time)
tumbling window that groups items onto an array,
either every size
items, or within time
ms,
which ever occurs earliest.
License
MIT