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.
Let X be a set and Ï a Ï-algebra over X. 1  A function Î¼ from Ï to the extended real number line is called a measure if it satisfies the following properties: 2  Non-negativity: For all E in Ï: Î¼(E) â¥ 0. 3  Null empty set: Î¼(â) = 0.