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.
(mathematics, not comparable, of a set in an Euclidean space) Closed and bounded. A set S of real numbers is called compact if every sequence in S has a subsequence that converges to an element again contained in S. (topology, not comparable, of a set) Such that every open cover of the given set has a finite subcover. Brief; close; pithy; not diffuse; not verbose. a compact discourse.