Javascript将数组元素相互组合的最有效方法

Question

I'm trying to combine arrays of string with unique combinations, like 'Mark|Tom' but without 'Tom|Mark'

I have written this code:

 let arr = ['Tom', 'Danny', 'Mark'] let sets = [] for (let i = 0; i < arr.length; i++) { let others = arr.filter(name => name != arr[i]) others.forEach((other) => { let newel = arr[i] + '|' + other let test = newel.split('|') if (sets.includes(test[1] + '|' + test[0]) || sets.includes(newel)) return sets.push(newel) }) } console.log(sets) 

This is iterating through every array element and then creating another array of other elements from basic array and then iterating through them (again iteration), creating a combination, checking if there is reversed combination of our elements (if this was created in previous loops) and if there is no such combination = push it to target array.

Is there more elegant way to do that task?

Answer 1

what about this one:

 const arr = ['Tom', 'Danny', 'Mark']; const sets = []; for (let i = 0; i < arr.length; i++) { for (let j = i + 1; j < arr.length; j++) { sets.push(arr[i] + '|' + arr[j]); } } console.log(sets); 

Also you can make arr unique before start the calculate:

const arr = [...new Set(['Tom', 'Danny', 'Mark', 'Tom'])]; // ['Tom', 'Danny', 'Mark']

Answer 2

I would make your array a set so it will remove all duplicates initially like so:

new Set(['Tom', 'Danny', 'Mark']);

Now, you can pair the i th element with all elements up to the n th element using .flatMap and .reduce like so:

 const name_arr = Array.from(new Set(['Tom', 'Danny', 'Mark'])); const res = name_arr.flatMap( (name, i) => name_arr.slice(i+1).reduce((a, n) => [...a, name+'|'+n],[]) ); console.log(res); 

Answer 3

You can create a Set of passed array, loop through the array, for each index get the array after that index and loop thorough this other array and build combinations

 let arr = ['Tom', 'Danny', 'Mark'] const uniqueCombo = (arr) => { let newSet = [...new Set(arr)] return newSet.reduce((op, inp, index) => { newSet.slice(index + 1,).forEach(v => { op.push(inp + '|' + v) }) return op },[]) } console.log(uniqueCombo(arr)) console.log(uniqueCombo(['A', 'B', 'A', 'C', 'D'])) console.log(uniqueCombo(['A', 'B', 'A', 'C'])) 

Answer 4

Try this one. This approach filters out the index which has been previously used to push item to array.

 const arr = ['Tom', 'Danny', 'Mark']; const comb = []; for (let i = 0; i < arr.length; i++) { for (j = i + 1; j < arr.length; j++) { comb.push(arr[i] + '|' + arr[j]); } } console.log(comb);