fulcrum

Array Pivot
======

A utility to generate pivot tables from an array of objects:

var pivot = require('fulcrum');

var data = [{
name: 'John',
coin: '5ct',
number: 30
},{
name: 'John',
coin: '5ct',
number: 2
},{
name: 'John',
coin: '10ct',
number: 3
},{
name: 'Jane',
coin: '10ct',
number: 15
},{
name: 'Jane',
coin: '5ct',
number: 6
}];

In this data model, John has 32 5ct and 3 10ct coins, Jane has 6 5ct and 15 10ct coins.

var res = pivot(data,'name','coin',pivot.sum('number'));

[{
"name": "John",
"5ct": 32,
"10ct": 3
},{
"name": "Jane",
"5ct": 6,
"10ct": 15
}]

API
---

pivot(array,rows,cols,reducer);

- array: an array of objects
- rows: a string for the field for rows
- cols: a string for the field for columns
- reducer (optional): an object describing how to calculate the cell value from the matched objects:

{
callback: Function,
initialValue: Object
}

These are the same arguments as passed into Array.reduce: .

If the reducer is omitted, an array of objects is returned in the cell

Built in reducers
----------------

- pivot.sum(field): return the sum of the values in field field
- pivot.count(): return the number of objects in the cell
- pivot.average(field): return the average
- pivot.min(field): return the minimum
- pivot.max(field): return the maximum

For all these reducers, when no objects are present in the cell, null is returned, except for count()

Convenience attachments to Array.prototype
--------------------

If you wish, you can attach a convenience method to Array.prototype:

var pivot = require('fulcrum').attach();
var res = data.pivot('name','coin',pivot.sum('number'));

It can also be detached:

pivot.detach();