Underscore.js _.partitionBy() Method
The_.partitionBy() method takes an array and a function and hence generates a partitioned array based on the conditions of the given function.
Syntax:
_.partitionBy(array, function)
Parameters:
- array: The given array from which the partitioned array is to be created.
- function: The function containing the conditions for an array to be partitioned.
Return Value: This method returns a newly created partitioned array.
Note: This will not work in normal JavaScript because it requires the underscore.js contribute library to be installed.
underscore.js contrib library can be installed using:
npm install underscore-contrib –save
Example 1: In this example, we will create a partitioned array of even and odd elements using this method.
javascript
const _ = require( 'underscore-contrib' );
let array = [1, 2, 3, 2, 1, 1, 5, 6, 6, 6, 7, 8, 9, 9, 10];
let p_arr = _.partitionBy(array, _.isOdd);
console.log( "Original Array : " , array);
console.log( "Partitioned Array: " , p_arr);
|
Output:
Original Array : [
1, 2, 3, 2, 1, 1,
5, 6, 6, 6, 7, 8,
9, 9, 10
]
Partitioned Array: [
[ 1 ], [ 2 ],
[ 3 ], [ 2 ],
[ 1, 1, 5 ], [ 6, 6, 6 ],
[ 7 ], [ 8 ],
[ 9, 9 ], [ 10 ]
]
Example 2: In this example, we will create a partitioned array of all identical elements.
javascript
const _ = require( 'underscore-contrib' );
let array = [1, 2, 3, 2, 1, 1, 5, 6, 6, 6, 7, 8, 9, 9, 10];
let p_arr = _.partitionBy(array, _.identity);
console.log( "Original Array : " , array);
console.log( "Partitioned Array: " , p_arr);
|
Output:
Original Array : [
1, 2, 3, 2, 1, 1,
5, 6, 6, 6, 7, 8,
9, 9, 10
]
Partitioned Array: [
[ 1 ], [ 2 ],
[ 3 ], [ 2 ],
[ 1, 1 ], [ 5 ],
[ 6, 6, 6 ], [ 7 ],
[ 8 ], [ 9, 9 ],
[ 10 ]
]
Example 3: In this example, we will create a partitioned array of all negative and positive numbers.
javascript
const _ = require( 'underscore-contrib' );
let array = [1, 2, 3, 2, -1, -1, 5, 6, -6, -6, -7, -8, 9, 9, 10];
let p_arr = _.partitionBy(array, function (val) {
return val > 0
});
console.log( "Original Array : " , array);
console.log( "Partitioned Array: " , p_arr);
|
Output:
Original Array : [
1, 2, 3, 2, -1, -1,
5, 6, -6, -6, -7, -8,
9, 9, 10
]
Partitioned Array: [
[ 1, 2, 3, 2 ],
[ -1, -1 ],
[ 5, 6 ],
[ -6, -6, -7, -8 ],
[ 9, 9, 10 ]
]
Last Updated :
05 Apr, 2023
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