About stdlib...

We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.

The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

FancyArray

Fancy multidimensional array constructor.

A FancyArray is an ndarray which supports slicing via indexing expressions.

varndarray2array=require('@stdlib/ndarray-to-array');varFancyArray=require('@stdlib/ndarray-fancy');varbuffer=[1,2,3,4,5,6];varx=newFancyArray('generic',buffer,[6],[1],0,'row-major');// returns <FancyArray>// Select the first 3 elements:vary=x[':3'];// returns <FancyArray>vararr=ndarray2array(y);// returns [ 1, 2, 3 ]// Select every other element, starting with the second element:y=x['1::2'];// returns <FancyArray>arr=ndarray2array(y);// returns [ 2, 4, 6 ]// Reverse the array, starting with last element and skipping every other element:y=x['::-2'];// returns <FancyArray>arr=ndarray2array(y);// returns [ 6, 4, 2 ]

Installation

npm install @stdlib/ndarray-fancy

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

varFancyArray=require('@stdlib/ndarray-fancy');

FancyArray( dtype, buffer, shape, strides, offset, order[, options] )

Returns a FancyArray instance.

// Specify the array configuration:varbuffer=[1.0,2.0,3.0,4.0];varshape=[2,2];varorder='row-major';varstrides=[2,1];varoffset=0;// Create a new array:vararr=newFancyArray('generic',buffer,shape,strides,offset,order);// returns <FancyArray>

The constructor expects the following arguments:

• dtype: underlying data type.
• buffer: data buffer.
• shape: array shape (dimensions).
• strides: array strides which are index offsets specifying how to access along corresponding dimensions.
• offset: index offset specifying the location of the first indexed element in the data buffer.
• order: array order, which is either row-major (C-style) or column-major (Fortran-style).

The constructor accepts the following options:

• mode: specifies how to handle indices which exceed array dimensions. Default: 'throw'.
• submode: a mode array which specifies for each dimension how to handle subscripts which exceed array dimensions. If provided fewer modes than dimensions, the constructor recycles modes using modulo arithmetic. Default: [ options.mode ].
• readonly: boolean indicating whether an array should be read-only. Default: false.

The constructor supports the following modes:

• throw: specifies that a FancyArray instance should throw an error when an index exceeds array dimensions.
• normalize: specifies that a FancyArray instance should normalize negative indices and throw an error when an index exceeds array dimensions.
• wrap: specifies that a FancyArray instance should wrap around an index exceeding array dimensions using modulo arithmetic.
• clamp: specifies that a FancyArray instance should set an index exceeding array dimensions to either 0 (minimum index) or the maximum index.

By default, a FancyArray instance throws when provided an index which exceeds array dimensions. To support alternative indexing behavior, set the mode option, which will affect all public methods (but not slicing semantics) for getting and setting array elements.

varopts={'mode': 'clamp'};// Specify the array configuration:varbuffer=[1.0,2.0,3.0,4.0];varshape=[2,2];varorder='row-major';varstrides=[2,1];varoffset=0;// Create a new array:vararr=newFancyArray('generic',buffer,shape,strides,offset,order,opts);// returns <FancyArray>// Attempt to access an out-of-bounds linear index (clamped):varv=arr.iget(10);// returns 4.0

By default, the mode option is applied to subscripts which exceed array dimensions. To specify behavior for each dimension, set the submode option.

varopts={'submode': ['wrap','clamp']};// Specify the array configuration:varbuffer=[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0];varshape=[2,2,2];varorder='row-major';varstrides=[4,2,1];varoffset=0;// Create a new array:vararr=newFancyArray('generic',buffer,shape,strides,offset,order,opts);// returns <FancyArray>// Attempt to access out-of-bounds subscripts:varv=arr.get(-2,10,-1);// linear index: 3// returns 4.0

---

Properties

FancyArray.name

String value of the constructor name.

varstr=FancyArray.name;// returns 'ndarray'

FancyArray.prototype.byteLength

Size (in bytes) of the array (if known).

varFloat64Array=require('@stdlib/array-float64');// Specify the array configuration:varbuffer=newFloat64Array([1.0,2.0,3.0,4.0]);varshape=[2,2];varorder='row-major';varstrides=[2,1];varoffset=0;// Create a new array:vararr=newFancyArray('float64',buffer,shape,strides,offset,order);// Get the byte length:varnbytes=arr.byteLength;// returns 32

If unable to determine the size of the array, the property value is null.

// Specify the array configuration:varbuffer=[1.0,2.0,3.0,4.0];varshape=[2,2];varorder='row-major';varstrides=[2,1];varoffset=0;// Create a new array:vararr=newFancyArray('generic',buffer,shape,strides,offset,order);// Get the byte length:varnbytes=arr.byteLength;// returns null

FancyArray.prototype.BYTES_PER_ELEMENT

Size (in bytes) of each array element (if known).

varFloat32Array=require('@stdlib/array-float32');// Specify the array configuration:varbuffer=newFloat32Array([1.0,2.0,3.0,4.0]);varshape=[2,2];varorder='row-major';varstrides=[2,1];varoffset=0;// Create a new array:vararr=newFancyArray('float32',buffer,shape,strides,offset,order);// Get the number of bytes per element:varnbytes=arr.BYTES_PER_ELEMENT;// returns 4

If size of each array element is unknown, the property value is null.

// Specify the array configuration:varbuffer=[1.0,2.0,3.0,4.0];varshape=[2,2];varorder='row-major';varstrides=[2,1];varoffset=0;// Create a new array:vararr=newFancyArray('generic',buffer,shape,strides,offset,order);// Get the number of bytes per element:varnbytes=arr.BYTES_PER_ELEMENT;// returns null

FancyArray.prototype.data

A reference to the underlying data buffer.

varInt8Array=require('@stdlib/array-int8');// Specify the array configuration:varbuffer=newInt8Array([1,2,3,4]);varshape=[2,2];varorder='row-major';varstrides=[2,1];varoffset=0;// Create a new array:vararr=newFancyArray('int8',buffer,shape,strides,offset,order);// Get the buffer reference:vard=arr.data;// returns <Int8Array>[ 1, 2, 3, 4 ]varbool=(d===buffer);// returns true

FancyArray.prototype.dtype

Underlying data type.

varUint8Array=require('@stdlib/array-uint8');// Specify the array configuration:varbuffer=newUint8Array([1,2,3,4]);varshape=[2,2];varorder='row-major';varstrides=[-2,1];varoffset=2;// Create a new array:vararr=newFancyArray('uint8',buffer,shape,strides,offset,order);// Get the underlying data type:vardtype=arr.dtype;// returns 'uint8'

FancyArray.prototype.flags

Meta information, such as information regarding the memory layout of the array. The returned object has the following properties:

• ROW_MAJOR_CONTIGUOUS: boolean indicating if an array is row-major contiguous.
• COLUMN_MAJOR_CONTIGUOUS: boolean indicating if an array is column-major contiguous.
• READONLY: boolean indicating whether an array is read-only.

An array is contiguous if (1) an array is compatible with being stored in a single memory segment and (2) each array element is adjacent to the next array element. Note that an array can be both row-major contiguous and column-major contiguous at the same time (e.g., if an array is a 1-dimensional array with strides = [1]).

varInt32Array=require('@stdlib/array-int32');// Specify the array configuration:varbuffer=newInt32Array([1,2,3,4]);varshape=[2,2];varorder='column-major';varstrides=[1,2];varoffset=0;// Create a new array:vararr=newFancyArray('int32',buffer,shape,strides,offset,order);// Get the array flags:varflg=arr.flags;// returns {...}

FancyArray.prototype.length

Number of array elements.

varUint16Array=require('@stdlib/array-uint16');// Specify the array configuration:varbuffer=newUint16Array([1,2,3,4]);varshape=[2,2];varorder='column-major';varstrides=[-1,-2];varoffset=3;// Create a new array:vararr=newFancyArray('uint16',buffer,shape,strides,offset,order);// Get the array length:varlen=arr.length;// returns 4

FancyArray.prototype.ndims

Number of dimensions.

varUint8ClampedArray=require('@stdlib/array-uint8c');// Specify the array configuration:varbuffer=newUint8ClampedArray([1,2,3,4]);varshape=[2,2];varorder='row-major';varstrides=[-2,-1];varoffset=3;// Create a new array:vararr=newFancyArray('uint8c',buffer,shape,strides,offset,order);// Get the number of dimensions:varndims=arr.ndims;// returns 2

FancyArray.prototype.offset

Index offset which specifies the buffer index at which to start iterating over array elements.

varInt16Array=require('@stdlib/array-int16');// Specify the array configuration:varbuffer=newInt16Array([1,2,3,4,5,6,7,8,9,10,11,12]);varshape=[2,2];varorder='row-major';varstrides=[-2,-1];varoffset=10;// Create a new array:vararr=newFancyArray('int16',buffer,shape,strides,offset,order);// Get the index offset:varo=arr.offset;// returns 10

FancyArray.prototype.order

Array order. The array order is either row-major (C-style) or column-major (Fortran-style).

varUint32Array=require('@stdlib/array-uint32');// Specify the array configuration:varbuffer=newUint32Array([1,2,3,4]);varshape=[2,2];varorder='row-major';varstrides=[2,1];varoffset=0;// Create a new array:vararr=newFancyArray('uint32',buffer,shape,strides,offset,order);// Get the array order:varord=arr.order;// returns 'row-major'

FancyArray.prototype.shape

Returns a copy of the array shape.

// Specify the array configuration:varbuffer=[1.0,2.0,3.0,4.0,5.0,6.0];varshape=[2,2];varorder='row-major';varstrides=[2,1];varoffset=2;// Create a new array:vararr=newFancyArray('generic',buffer,shape,strides,offset,order);// Get the array shape:vardims=arr.shape;// returns [ 2, 2 ]

FancyArray.prototype.strides

Returns a copy of the array strides which specify how to access data along corresponding array dimensions.

// Specify the array configuration:varbuffer=[1.0,2.0,3.0,4.0];varshape=[2,2];varorder='column-major';varstrides=[-1,2];varoffset=1;// Create a new array:vararr=newFancyArray('generic',buffer,shape,strides,offset,order);// Get the array strides:vars=arr.strides;// returns [ -1, 2 ]

---

Methods

FancyArray.prototype.get( i, j, k, ... )

Returns an array element specified according to provided subscripts. The number of provided subscripts must equal the number of dimensions.

// Specify the array configuration:varbuffer=[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0];varshape=[2,2];varorder='row-major';varstrides=[2,1];varoffset=2;// Create a new array:vararr=newFancyArray('generic',buffer,shape,strides,offset,order);// Get the element located at (1,1):varv=arr.get(1,1);// returns 6.0

FancyArray.prototype.iget( idx )

Returns an array element located at a specified linear index.

// Specify the array configuration:varbuffer=[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0];varshape=[2,2];varorder='row-major';varstrides=[2,1];varoffset=2;// Create a new array:vararr=newFancyArray('generic',buffer,shape,strides,offset,order);// Get the element located at index 3:varv=arr.iget(3);// returns 6.0

For zero-dimensional arrays, the input argument is ignored and, for clarity, should not be provided.

FancyArray.prototype.set( i, j, k, ..., v )

Sets an array element specified according to provided subscripts. The number of provided subscripts must equal the number of dimensions.

// Specify the array configuration:varbuffer=[1.0,2.0,3.0,4.0];varshape=[2,2];varorder='row-major';varstrides=[2,1];varoffset=0;// Create a new array:vararr=newFancyArray('generic',buffer,shape,strides,offset,order);// Set the element located at (1,1):arr.set(1,1,40.0);varv=arr.get(1,1);// returns 40.0// Get the underlying buffer:vard=arr.data;// returns [ 1.0, 2.0, 3.0, 40.0 ]

The method returns the FancyArray instance. If an array is read-only, the method raises an exception.

FancyArray.prototype.iset( idx, v )

Sets an array element located at a specified linear index.

// Specify the array configuration:varbuffer=[1.0,2.0,3.0,4.0];varshape=[2,2];varorder='row-major';varstrides=[2,1];varoffset=0;// Create a new array:vararr=newFancyArray('generic',buffer,shape,strides,offset,order);// Set the element located at index 3:arr.iset(3,40.0);varv=arr.iget(3);// returns 40.0// Get the underlying buffer:vard=arr.data;// returns [ 1.0, 2.0, 3.0, 40.0 ]

For zero-dimensional arrays, the first, and only, argument should be the value v to set.

The method returns the FancyArray instance. If an array is read-only, the method raises an exception.

FancyArray.prototype.toString()

Serializes a FancyArray as a string.

// Specify the array configuration:varbuffer=[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0];varshape=[3,2];varorder='row-major';varstrides=[2,1];varoffset=2;// Create a new array:vararr=newFancyArray('generic',buffer,shape,strides,offset,order);// Serialize to a string:varstr=arr.toString();// returns "ndarray( 'generic', [ 3, 4, 5, 6, 7, 8 ], [ 3, 2 ], [ 2, 1 ], 0, 'row-major' )"

The method does not serialize data outside of the buffer region defined by the array configuration.

FancyArray.prototype.toJSON()

Serializes a FancyArray as a JSON object. JSON.stringify() implicitly calls this method when stringifying a FancyArray instance.

// Specify the array configuration:varbuffer=[1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0];varshape=[3,2];varorder='row-major';varstrides=[2,1];varoffset=2;// Create a new array:vararr=newFancyArray('generic',buffer,shape,strides,offset,order);// Serialize to JSON:varo=arr.toJSON();// returns { 'type': 'ndarray', 'dtype': 'generic', 'flags': {...}, 'offset': 0, 'order': 'row-major', 'shape': [ 3, 2 ], 'strides': [ 2, 1 ], 'data': [ 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] }

The method does not serialize data outside of the buffer region defined by the array configuration.

---

Notes

• To create a zero-dimensional array, provide an empty shape and a single strides element equal to 0. The order can be either row-major or column-major and has no effect on data storage or access.

  varbuffer=[1];varshape=[];varorder='row-major';varstrides=[0];varoffset=0;// Create a new zero-dimensional array:vararr=newFancyArray('generic',buffer,shape,strides,offset,order);// returns <FancyArray>

• A FancyArray is an ndarray instance and supports all ndarray options, attributes, and methods. A FancyArray can be consumed by any API which supports ndarray instances.

• Indexing expressions provide a convenient and powerful means for creating and operating on ndarray views; however, their use does entail a performance cost. Indexing expressions are best suited for interactive use (e.g., in the REPL) and scripting. For performance critical applications, prefer equivalent functional APIs supporting ndarray instances.

• In older JavaScript environments which do not support Proxy objects, the use of indexing expressions is not supported.

---

Examples

varS=require('@stdlib/slice-ctor');varE=require('@stdlib/slice-multi');vartoArray=require('@stdlib/ndarray-to-array');varFancyArray=require('@stdlib/ndarray-fancy');varbuffer=[1,2,3,4,// 05,6,// 17,8,// 29,10];varshape=[3,2];varstrides=[2,1];varoffset=2;varx=newFancyArray('generic',buffer,shape,strides,offset,'row-major');// returns <FancyArray>// Access an ndarray property:varndims=x.ndims;// returns 2// Retrieve an ndarray element:varv=x.get(2,1);// returns 8// Set an ndarray element:x.set(2,1,20);v=x.get(2,1);// returns 20// Create an alias for `undefined` for more concise slicing expressions:var_=void0;// Create a multi-dimensional slice:vars=E(S(0,_,2),_);// returns <MultiSlice>// Use the slice to create a view on the original ndarray:vary1=x[s];console.log(toArray(y1));// => [ [ 3, 4 ], [ 7, 20 ] ]// Use alternative syntax:vary2=x[[S(0,_,2),_]];console.log(toArray(y2));// => [ [ 3, 4 ], [ 7, 20 ] ]// Use alternative syntax:vary3=x['0::2,:'];console.log(toArray(y3));// => [ [ 3, 4 ], [ 7, 20 ] ]// Flip dimensions:vary4=x[[S(_,_,-2),S(_,_,-1)]];console.log(toArray(y4));// => [ [ 20, 7 ], [ 4, 3 ] ]

---

See Also

• @stdlib/ndarray-array: multidimensional arrays.
• @stdlib/ndarray-ctor: multidimensional array constructor.

---

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

---

License

See LICENSE.

Copyright

Copyright © 2016-2026. The Stdlib Authors.