Question

A list of Equity Analytics (stocks) objects doing a calculation for daily returns.
Was thinking there must be a pairwise solution to do this:

for(int i = 0; i < sdata.Count; i++){
    sdata[i].DailyReturn = (i > 0) ? (sdata[i-1].AdjClose/sdata[i].AdjClose) - 1
                                   : 0.0;
}

Answer 1

I’m new to LINQ, I started using it because of stackoverflow so I tried to play with your question, and I know this may attract downvotes but I tried and it does what you want in case there is at least one element in the list.

sdata[0].DailyReturn = 0.0;
sdata.GetRange(1, sdata.Count - 1).ForEach(c => c.DailyReturn = (sdata[sdata.IndexOf(c)-1].AdjClose / c.AdjClose) - 1);

But must say that avoiding for loops isn’t the best practice. from my point of view, LINQ should be used where convenient and not everywhere. Good old loops are sometimes easier to maintain.