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TimeBucket

Group timestamps into "buckets" by applying a granularity to a discrete value

A timebucket is a type of time domain which combines a size identifier (granularity) with a discrete value, and can be stored as a compact string.

Timebuckets are useful for grouping timestamps together using a particular granularity (such as groups of 30 minutes), as an aid for graphing or map/reduce-ing time-series data.

Also, timebuckets can serve as a neutral format between which UNIX timestamps (seconds before or after 1970) and millisecond timestamps (as used in JavaScript) can be converted, and stored in a complete way (with granularity attached).

Anatomy of a timebucket

A timebucket consists of:

1. a size spec (string) which consists of:
2. (optional) an unsigned multiplier (default: 1)
3. a granularity identifier, i.e. s for seconds
4. a signed value, i.e. number of seconds, after or before epoch year (1970)

Format examples

• 8h-491 - time (within 8 hours) of first moonwalk (1969-07-21 02:56 UTC)
• y43 - the year 2013

API

Construction

The timebucket module exports a factory function. It supports the following argument combinations:

• timebucket() - build timebucket with millisecond granularity applied to current date
• timebucket(size) - build from specific size (string identifier, see list below) applied to current date
• timebucket(milliseconds) - build from milliseconds since 1970
• timebucket(size, value) - build from specific size and value
• timebucket(date) - build from date object with millisecond granularity
• timebucket(str) - build from string representation

Resizing

To resize a bucket, call resize(newSize):

console.log(timebucket('y').resize('30m') + '')
// '30m753360'

Conversion

Conversion methods:

• toString() - convert to string representation
• toJSON() - same as toString()
• toMilliseconds() - convert to millisecond UNIX time offset
• toDate() - convert to Date object

API examples

var timebucket = require('timebucket')

// defaults to current milliseconds after unix epoch
console.log(timebucket() + '')
// 'ms1369656669680'

// default size (milliseconds) and value
console.log(timebucket(1369601120380) + '')
// 'ms1369601120380'

// specific size (seconds) and value
console.log(timebucket('s', 1369601125) + '')
// 's1369601125'

// resize to year
console.log(timebucket().resize('y') + '')
// 'y43'

// use current time, specific size
console.log(timebucket('30m') + '')
// '30m760920'

// create timebucket from current seconds after unix epoch, and add 5
console.log(timebucket('s').add(5) + '')
// 's1369656674'

// from date object
console.log(timebucket(new Date()) + '')
// 'ms1369656669686'

// from string representation
console.log(timebucket('y43') + '')
// 'y43'

// access granularity and value as properties
var t = timebucket()
console.log(t.size.value, t.size.granularity, t.value)
// 1 'ms' 1369656669686

// resize
console.log(timebucket('y').resize('30m') + '')
// '30m753360'

Granularity identifiers

• ms - milliseconds
• s - seconds
• m - minutes
• h - hours
• d - days
• w - weeks
• M - months
• y - years

Integer storage

Timebuckets also have a 64-bit integer representation which contains granularity metadata, while maintaining sortability with buckets of the same granularity.

var timebucket = require('timebucket')
var num = timebucket('8h-491').toNumber()
// toNumber() returns a 64-bit integer representation as a Number
console.log(num)
// -49133
var bucket = timebucket.fromNumber(num)
// fromNumber() takes the result of toNumber(), and returns a timebucket instance:
console.log(bucket.toString())
// 8h-491