So if you want to change the scale from Fahrenheit to Celsius in the weather app, here is how to do it. The following method is for Windows Consumer Preview and Release Preview.
When data seems to be gathered around a particular value. For example: for the values 2, 6, 7, 8, 8.5, 10, 15, there is a cluster around the value 8. See: Outlier.
When the number of clusters is fixed to k, k-means clustering gives a formal definition as an optimization problem: find the k cluster centers and assign the objects to the nearest cluster center, such that the squared distances from the cluster are minimized.