How to find point between two keys in sorted dictionary

Question

I have a sorted dictionary that contains measured data points as key/value pairs. To determine the value for a non-measured data point I want to extrapolate the value between t

Answer 1

Something like this would work:

 dic.Keys.Zip(dic.Keys.Skip(1), 
              (a, b) => new { a, b })
         .Where(x => x.a <= datapoint && x.b >= datapoint)
         .FirstOrDefault();

This traverses they keys using the fact that they are ordered and compares all two keys following each other in order - since LINQ is lazy once you find the first match the traversal will stop.