flatten-objects-array v0.0.13

flatten-objects-array

automatically flatten a list of similar objects into a flat array (or array of arrays)...

then un-flatten the result back into the original objects' format again.

can also convert arbitrary objects arrays to csv with objectsArrayToCSV

and can also interpolate between arbitrary numerical objects with objectsInterpolate

Installation

npm i flatten-objects-array

Usage

var {
    loadObjectsFromArrayOfArrays,
    loadObjectsIntoArrayOfArrays,
    loadObjectsIntoIntArray,
    loadObjectsIntoFloatArray,
    loadObjectsIntoArray,
    loadObjectsFromArray,
    getObjectFieldsList,
    objectsArrayToCSV,
    objectsInterpolate
    // getValueFromPath, //these are used internally but exposed for convenience
    // getTypeFromPath,
    // getType,
    // setFieldValue,
    // buildObjectFromFields
} = require('flatten-objects-array');

//the first object in the list serves as the template!
//notice how the 2nd object has data missing.
var objects = [{
    color: [0,1,3],
    stuff: {
        my_matrix: [[1,2],[4,5]]
    },
    height: 53,
},
{
    color: [77,123,32],
    stuff: {
        my_matrix: [[1,1],null] //malformed example
    },
    height: "not-a-number"
}];

//note -- objects with only numeric fields get replaced by arrays!
// {
//     obj: {0: 1} //<-- this will be converted into an array
// }

var fields = getObjectFieldsList(objects[0]); //optionally get list of fields like "field.subfield.etc"
var arrFlatFloat = loadObjectsIntoFloatArray(objects, fields); //load objs into float32 array [fields optional, auto-detected]
var arrFlatInt = loadObjectsIntoIntArray(objects, fields); //load objs into int32 array [fields optional, auto-detected]
var arrFlatUntyped = loadObjectsIntoArray(objects, fields); //load objs into untyped array [fields optional, auto-detected]
var arrPerObj = loadObjectsIntoArrayOfArrays(objects, fields); //retrieve a simple array per-object [fields optional, auto-detected]
var objsAgainFromArrFlatFloat = loadObjectsFromArray(arrFlatFloat, fields); //expand back into objects [fields required]
var objsAgainFromArrFlatUntyped = loadObjectsFromArray(arrFlatUntyped, fields); //expand back into objects [fields required]
var objsAgainFromArrOfArrs = loadObjectsFromArrayOfArrays(arrPerObj, fields); //expand back into objects [fields required]

console.log({ fields, arrFlatFloat, arrPerObj, objsAgainFromArrFlatFloat, objsAgainFromArrFlatUntyped, objsAgainFromArrOfArrs});

//notice how using typed arrays replaces non-numeric information with NaN.
//eg, if you want to preserve non-numeric data, do not use typed arrays

// {
//     fields: [
//         'color.0',
//         'color.1',
//         'color.2',
//         'stuff.my_matrix.0.0',
//         'stuff.my_matrix.0.1',
//         'stuff.my_matrix.1.0',
//         'stuff.my_matrix.1.1',
//         'height'
//     ],
//     arrFlatFloat: Float32Array(16) [
//         0,   1,   3,   1,  2, 4,
//         5,  53,  77, 123, 32, 1,
//         1, NaN, NaN, NaN
//     ],
//     arrPerObj: [
//         [0, 1, 3,  1, 2, 4, 5, 53],
//         [ 77, 123, 32, 1, 1, undefined, undefined, 'not-a-number' ]
//     ],
//     objsAgainFromArrFlatFloat: [
//         { color: [Array], stuff: [Object], height: 53 },
//         { color: [Array], stuff: [Object], height: NaN }
//     ],
//     objsAgainFromArrFlatUntyped: [
//         { color: [Array], stuff: [Object], height: 53 },
//         { color: [Array], stuff: [Object], height: 'not-a-number' }
//     ],
//     objsAgainFromArrOfArrs: [
//         { color: [Array], stuff: [Object], height: 53 },
//         { color: [Array], stuff: [Object], height: 'not-a-number' }
//     ]
// }

console.log(objsAgainFromArrFlatFloat[0].stuff.my_matrix)
//    [ [ 1, 2 ], [ 3, 4 ] ]
console.log(objsAgainFromArrFlatFloat[1].stuff.my_matrix)
//    [ [ 1, 1 ], [ NaN, NaN ] ]

var sep = ','; //default
var newline = '\n'; //default
//convert to csv string
console.log(objectsArrayToCSV(objects, sep, newline));
// color.0,color.1,color.2,stuff.my_matrix.0.0,stuff.my_matrix.0.1,stuff.my_matrix.1.0,stuff.my_matrix.1.1,height
// 0,1,3,1,2,4,5,53
// 77,123,32,1,1,,,not-a-number

//note the header is made from fields of first object 

//linear interpolation between arbitrary objects with numerical fields [non numerical fields will cause an err]
var objA= {r:0,g:0,b:0, coords: {u:0,v:0}}
var objB= {r:255,g:255,b:255, coords: {u:1,v:1}}

console.log(objectsInterpolate(objA,objB,0.5));
//{ r: 127.5, g: 127.5, b: 127.5, coords: { u: 0.5, v: 0.5 } }

See Also

There are several similar libraries achieving slightly different goals

• struct - structs like from C
• flatten-unflatten - flatten object field names
• flatten - for flattening arrays
• flatten-objects - for creating multiples of objects
• normalize-denormalize - normalize-denormalize lists of n-dimensional points/objects