cluster

Group an array by specified conditions.

Syntax

cluster<T>(
  array: T[],
  key: (item: T) => string | number
): Record<string | number, T[]>

Parameters

• array (T[]): The array to group
• key ((item: T) => string | number): Key extraction function for grouping

Return Value

• Record<string | number, T[]>: Grouped object, keys are grouping conditions, values are corresponding arrays

Examples

Basic Usage

import { cluster } from 'radash'

const users = [
  { name: 'Alice', age: 25, city: 'New York' },
  { name: 'Bob', age: 30, city: 'Los Angeles' },
  { name: 'Charlie', age: 25, city: 'New York' },
  { name: 'Diana', age: 35, city: 'Los Angeles' }
]

const groupedByCity = cluster(users, user => user.city)
// {
//   'New York': [
//     { name: 'Alice', age: 25, city: 'New York' },
//     { name: 'Charlie', age: 25, city: 'New York' }
//   ],
//   'Los Angeles': [
//     { name: 'Bob', age: 30, city: 'Los Angeles' },
//     { name: 'Diana', age: 35, city: 'Los Angeles' }
//   ]
// }

Group by Age

import { cluster } from 'radash'

const users = [
  { name: 'Alice', age: 25 },
  { name: 'Bob', age: 30 },
  { name: 'Charlie', age: 25 },
  { name: 'Diana', age: 35 },
  { name: 'Eve', age: 30 }
]

const groupedByAge = cluster(users, user => user.age)
// {
//   25: [
//     { name: 'Alice', age: 25 },
//     { name: 'Charlie', age: 25 }
//   ],
//   30: [
//     { name: 'Bob', age: 30 },
//     { name: 'Eve', age: 30 }
//   ],
//   35: [
//     { name: 'Diana', age: 35 }
//   ]
// }

Group by Multiple Conditions

import { cluster } from 'radash'

const products = [
  { name: 'Laptop', category: 'Electronics', price: 999 },
  { name: 'Phone', category: 'Electronics', price: 599 },
  { name: 'Book', category: 'Education', price: 29 },
  { name: 'Tablet', category: 'Electronics', price: 399 }
]

const groupedByCategory = cluster(products, product => product.category)
// {
//   'Electronics': [
//     { name: 'Laptop', category: 'Electronics', price: 999 },
//     { name: 'Phone', category: 'Electronics', price: 599 },
//     { name: 'Tablet', category: 'Electronics', price: 399 }
//   ],
//   'Education': [
//     { name: 'Book', category: 'Education', price: 29 }
//   ]
// }

Group by Price Range

import { cluster } from 'radash'

const products = [
  { name: 'Laptop', price: 999 },
  { name: 'Phone', price: 599 },
  { name: 'Book', price: 29 },
  { name: 'Tablet', price: 399 },
  { name: 'Watch', price: 199 }
]

const getPriceRange = (price: number) => {
  if (price < 100) return 'Budget'
  if (price < 500) return 'Mid-range'
  return 'Premium'
}

const groupedByPriceRange = cluster(products, product => getPriceRange(product.price))
// {
//   'Budget': [
//     { name: 'Book', price: 29 }
//   ],
//   'Mid-range': [
//     { name: 'Watch', price: 199 },
//     { name: 'Tablet', price: 399 }
//   ],
//   'Premium': [
//     { name: 'Phone', price: 599 },
//     { name: 'Laptop', price: 999 }
//   ]
// }

Group by Date

import { cluster } from 'radash'

const events = [
  { title: 'Meeting 1', date: new Date('2023-01-01') },
  { title: 'Meeting 2', date: new Date('2023-01-01') },
  { title: 'Meeting 3', date: new Date('2023-01-02') },
  { title: 'Meeting 4', date: new Date('2023-01-03') }
]

const groupedByDate = cluster(events, event => 
  event.date.toISOString().split('T')[0]
)
// {
//   '2023-01-01': [
//     { title: 'Meeting 1', date: new Date('2023-01-01') },
//     { title: 'Meeting 2', date: new Date('2023-01-01') }
//   ],
//   '2023-01-02': [
//     { title: 'Meeting 3', date: new Date('2023-01-02') }
//   ],
//   '2023-01-03': [
//     { title: 'Meeting 4', date: new Date('2023-01-03') }
//   ]
// }

Handling Null Values

import { cluster } from 'radash'

const items = [
  { name: 'Item 1', category: 'A' },
  { name: 'Item 2', category: null },
  { name: 'Item 3', category: 'B' },
  { name: 'Item 4', category: undefined }
]

const groupedByCategory = cluster(items, item => item.category || 'Uncategorized')
// {
//   'A': [
//     { name: 'Item 1', category: 'A' }
//   ],
//   'B': [
//     { name: 'Item 3', category: 'B' }
//   ],
//   'Uncategorized': [
//     { name: 'Item 2', category: null },
//     { name: 'Item 4', category: undefined }
//   ]
// }

Notes

1. Key Type: Keys must be strings or numbers
2. Null Value Handling: Need to manually handle null and undefined values
3. Performance: Time complexity is O(n)
4. Order: Does not guarantee the order of elements within groups

Differences from Other Functions

• cluster: Group by conditions, returns an object
• groupBy: Similar functionality, but may have different implementations
• partition: Divides an array into two parts

Performance

• Time Complexity: O(n)
• Space Complexity: O(n)
• Use Cases: Data analysis and statistics