List Operators #

Introduction #

The package list_operators uses Dart extensions to provide additional operators for objects of type List<num> and List<T extends Comparable>.

Usage #

To use this package include list_operatos as a dependency in your pubspec.yaml file. The program below demonstrates how to use the operators and methods defined by the library list_operators.

Note: The + operator (concatenates two lists) is already defined by Dart's abstract class List and cannot be overridden by an extension on List. To add two numerical lists with same length use the method: List<num> plus(List<num> other).

import 'package:list_operators/list_operators.dart';

void main(List<String> args) {
  final a = [1, 2, 3];
  final b = [11, 12, 13];

  /// Use with List<num>
  print('Addition:');
  print(a.plus(b));

  print('\nSubtraction:');
  print(b - a);

  print('\nScalar product:');
  print(a * b);

  print('\nMultiplication:');
  print(a.times(10));

  print('\nPower');
  print(a.pow(2));

  print('\nb.distanceFromOrigin()');
  print(b.distanceFromOrigin);

  print('\nb.distance(a)');
  print(b.distance(a));


  /// Use with List<T extends Comparable>
  print('\na < b:');
  print(a < b);

  print('\na <= b:');
  print(a <= b);

  print('\na > b:');
  print(a > b);

  print('\nb >= b:');
  print(b >= b);

  final s1 = ['a1', 'a2'];
  final s2 = ['b1', 'b2'];

  print('\ns1 <= s2');
  print(s1 < s2);

  /// Provided by Dart
  print('\nConcatenation:');
  print(a + b);

  /// Exporting numerical lists to a `String` object.
  print('\nExporting lists to String:');
  print(a.export(
    label: 'Sample label',
    delimiter: ', ',
    precision: 4,
  ));

  print('\nExporting an object of type List<List<num>> to String:');
  print('Each inner list is exported as a row.');
  print([
    [1, 2, 3],
    [101, 102, 103]
  ].export(label: 'Sample label', precision: 6));

  print('\nExporting an object of type List<List<num>> to String.');
  print('Inner lists are exported as columns.');
  print([
    [1, 2, 3],
    [101, 102, 103]
  ].export(
    label: 'Sample label',
    precision: 6,
    flip: true,
  ));
}

dan@nano:~/list_operators$ dart example/bin/example.dart
Addition:
[12, 14, 16]

Subtraction:
[10, 10, 10]

Scalar product:
74

Multiplication:
[10, 20, 30]

Power
[1, 4, 9]

b.distanceFromOrigin()
20.83266665599966

b.distance(a)
17.320508075688775

a < b:
true

a <= b:
true

a > b:
false

b >= b:
true

s1 <= s2
true

Concatenation:
[1, 2, 3, 11, 12, 13]

Exporting lists to String:
Sample label
1.000,
2.000,
3.000,


Exporting an object of type List<List<num>> to String:
Each inner list is exported as a row.
Sample label
1.00000 2.00000 3.00000
101.000 102.000 103.000


Exporting an object of type List<List<num>> to String.
Inner lists are exported as columns.
Sample label
1.00000 101.000
2.00000 102.000
3.00000 103.000

Examples #

The program shown above is included in the folder example.

Features and bugs #

Please file feature requests and bugs at the issue tracker.