c# - Summing the previous values in an IEnumerable -

i have sequence of numbers:

var seq = new list<int> { 1, 3, 12, 19, 33 }; 

and want transform new sequence number added preceding numbers create new sequence:

{ 1, 3, 12, 19, 33 } --> {1, 4, 16, 35, 68 } 

i came following, dislike state variable 'count'. dislike fact i'm using values enumerable without acting on it.

int count = 1; var summed = values.select(_ => values.take(count++).sum()); 

how else done?

this common pattern in functional programming in f# called scan. it's c#'s enumerable.aggregate , f#'s fold except yields intermediate results of accumulator along final result. can implement scan in c# nicely extension method:

public static ienumerable<u> scan<t, u>(this ienumerable<t> input, func<u, t, u> next, u state) {     yield return state;     foreach(var item in input) {         state = next(state, item);         yield return state;     } } 

and use follows:

var seq = new list<int> { 1, 3, 12, 19, 33 }; var transformed = seq.scan(((state, item) => state + item), 0).skip(1);