lump

Count records in n contiguous buckets of equal size.

example

Given this records.json data:

{"rows":[
  {"x":52},
  {"x":41},
  {"x":12},
  {"x":46},
  {"x":65},
  {"x":73},
  {"x":88},
  {"x":66},
  {"x":22},
  {"x":44},
  {"x":60},
  {"x":59},
  {"x":81}
]}

lump

Pick off the x values and count them by bucket:

var lump = require('lump');
var fs = require('fs');
 
var records = JSON.parse(fs.readFileSync(__dirname + '/records.json'));
var lumps = lump(records, 5, [ 'rows', true, 'x' ])
console.dir(lumps);

---

[ { min: 12, max: 27.2, count: 2 },
  { min: 27.2, max: 42.4, count: 1 },
  { min: 42.4, max: 57.599999999999994, count: 3 },
  { min: 57.599999999999994, max: 72.8, count: 4 },
  { min: 72.8, max: 88, count: 2 } ]

stream

Or do the same thing with a stream:

var lump = require('lump');
var fs = require('fs');
var JSONStream = require('JSONStream');
 
var rs = fs.createReadStream(__dirname + '/records.json')
var parser = JSONStream.parse([ 'rows', /./, 'x' ]);
rs.pipe(parser);
 
var lumper = lump.stream(5);
parser.pipe(lumper);
lumper.on('end', function () {
    var x = lumper.lumps();
    console.dir(x);
});

---

[ { min: 12, max: 27.2, count: 2 },
  { min: 27.2, max: 42.4, count: 1 },
  { min: 42.4, max: 57.599999999999994, count: 3 },
  { min: 57.599999999999994, max: 72.8, count: 4 },
  { min: 72.8, max: 88, count: 2 } ]

methods

var lump = require('lump')

lump(data, size, path)

Return an array of buckets counting the number of values from data that fall within each bucket range.

Buckets are just objects with min, max, and count keys.

If the values to bucket are nested inside of data, specify the optional path parameter to read data at a pathway key path.

lump(opts)

Alternative form that calls lump(opts.data, opts.size, opts.path).

lump.stream(opts)

Return a writable stream that you write() data objects too. If the values needed for lumping are nested inside the objects written, use opts.path to specify the pathway key path to the values.

The call must have an opts.size to specify how many buckets to split the results among. If opts is a number, it will be treated as the opts.size.

install

With npm do:

npm install lump

license

MIT