find-streaks v1.0.1

find-streaks

Finds streaks of equal/same item, based on a monotonically increasing "time" property of them.

The following table shows how find-streaks works with a streak length of 3.

monotonic
timer      bucket  output
-------------------------
0          A       A starts
1          A
2          B       B starts
2          C       C starts
5          C       A ends
6          B       B ends, B starts
end                C ends, B ends

Installation

npm install find-streaks

Usage

These items represent the chart above:

const item1 = [0, 'a']
const item2 = [1, 'a']
const item3 = [2, 'b']
const item4 = [2, 'c']
const item4 = [5, 'c']
const item5 = [6, 'b']

Two items can be part of a streak if they have the same bucket(item), which must return a string or null.

find-streaks will tell if two items are witin a streak using monotonic(item), which must return an integer.

const streakLength = 3
const bucket = item => item[1]
const monotonic = item => item[0]

keeping only the last item of each streak

const keepLastOfStreaks = require('find-streaks')

const {check, flush} = keepLastOfStreaks(streakLength, bucket, monotonic)

check(item1) // []
check(item2) // []
check(item3) // []
check(item4) // []
check(item5) // [item2]
check(item6) // [item3]
flush() // [item5, item6]

as a transform stream

const keepLastStream = require('find-streaks/stream')

const keepLast = keepLastStream(streakLength, bucket, monotonic)
keepLast.on('data', console.log)
keepLast.write(item1)
// …
keepLast.end()

as a callbag operator

const keepLastCallbag = require('find-streaks/callbag')
const {pipe, fromIter, forEach} = require('callbag-basics')

const keepLast = keepLastCallbag(streakLength, bucket, monotonic)

pipe(
	fromIter([item1, item2, item3, item4, item5, item6]),
	keepLast,
	forEach(console.log)
)

finding raw starts & ends of streaks

const findStartsEnds = require('find-streaks/starts-ends')
const {START, END} = findStartsEnds

const {check, flush} = findStartsEnds(streakLength, bucket, monotonic)

check(item1) // ['a', START]
check(item2) // []
check(item3) // ['b', START]
check(item4) // ['c', START]
check(item5) // ['a', END]
check(item6) // ['b', END, 'b', START]
flush() // ['c', END, 'b', END]

Related

• lodash.debounce
• lodash.throttle
• callbag-keep-sequences – A callbag operator that passes through only sequences with minimum length.
• flatten-overlapping-ranges – Flatten overlapping ranges into a sequence of sections.

Contributing

If you have a question or need support using find-streaks, please double-check your code and setup first. If you think you have found a bug or want to propose a feature, use the issues page.