Some road type classifications are influenced by city size, traffic density, and regional conventions. For example, in a very large city a primary street may have three or more lanes in each direction on a divided road. While in a town of dirt roads, the only paved single lane street could be a primary street.
subset - a set whose members are members of another set; a set contained within another set. set - (mathematics) an abstract collection of numbers or symbols; the set of prime numbers is infinite. Translations. podmnoÅ¾ina.
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.