Performing Actions With Pairs in Arrays/Lists in C#-CodePudding

Sorry if the title's worded a bit weird but this is what I'm trying to get to.

Lets say you have an array of integers like this:

int[] arr = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

What would be the best way to use this array to return a new array but with the values of each pair summed together, so using the array above, it would return

{ 3, 7, 11, 15, 19 }

Obviously you can so something basic like

int[] arr = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
var x = new List<int>();
for (int i=0;i<arr.Length;i =2)
    x.Add(arr[i]   arr[i 1]);

But if you want to keep your code concise and/or work with different items, this doesn't really seem like the best option.

So is there any other/better way to do this? I was testing some ideas with Enumerable.Aggregate but couldn't come up with anything, please share ideas.

CodePudding user response：

Well, your code is readable and efficien; however, you can generalize your current solution a bit:

Last array item(s) can well have no pair
We can combine not only pairs, but three or four items etc.

If you are looking for such kind of code for

int[] arr = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

the modifiction of your solution can be:

const int size = 2;

int[] result = new int[arr.Length / size   Math.Sign(arr.Length % size)];

for (int i = 0; i < arr.Length;   i)
  result[i / size]  = arr[i];

For instance, if we set size = 3; then for we'll get { 6, 15, 24, 10 } as the result. Note, that the last group is incomplete:

   1, 2, 3, 4, 5, 6, 7, 8, 9, 10
   |     |  |     |  |     |  ||
      6        15       24    10

CodePudding user response：

I would argue that your approach is perfectly fine, but for LINQ you can do some stuff with Chunk:

var x = arr
    .Chunk(2)
    .Where(c => c.Length == 2)
    .Select(c => c.Sum())
    .ToArray();