While editing the maps, you may notice that some of the roads are not labeled properly. This means, the road type might be wrong (a highway is marked as a street) or that one road has a few road types (a highway is marked as Freeway, highway and primary at different segments). The importance of proper labeling is in two aspects:
Other sites. R 101: The Subset Function. The subset function is available in base R and can be used to return subsets of a vector, martix, or data frame which meet a particular condition. In my three years of using R, I have repeatedly used the subset() function and believe that it is the most useful tool for selecting elements of a data structure.
If A = {p, q} the proper subsets of A are [{ }, {p}, {q}] â Number of proper subsets of A are 3 = 2\(^{2}\) - 1 = 4 - 1. In general, number of proper subsets of a given set = 2\(^{m}\) - 1, where m is the number of elements.