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Simple example of an R-tree for 2D rectangles Visualization of an R*-tree for 3D cubes using ELKI R-trees are tree data structures used for spatial access methods , i.e., for indexing multi-dimensional information such as geographical coordinates , rectangles or polygons . The R-tree was proposed by Antonin Guttman in 1984 [ 1 ] and has found significant use in both theoretical and applied contexts. [ 2 ] A common real-world usage for an R-tree might be to store spatial objects such as restaurant locations or the polygons that typical maps are made of: streets, buildings, outlines of lakes, coastlines, etc. and then find answers quickly to queries such as "Find all museums within 2 km of my current location", "retrieve all road segments within 2 km of my location" (to display them in a navigation system ) or "find the nearest gas station" (although not taking roads into account). [ edit ] R-tree idea
R-tree
Fuzzy string searching
In computer science , approximate string matching (often colloquially referred to as fuzzy string searching ) is the technique of finding strings that match a pattern approximately (rather than exactly). The problem of approximate string matching is typically divided into two sub-problems: finding approximate substring matches inside a given string and finding dictionary strings that match the pattern approximately. [ edit ] Overview The closeness of a match is measured in terms of the number of primitive operations necessary to convert the string into an exact match. This number is called the edit distance between the string and the pattern. The usual primitive operations are: [1]
SQL ( pron.: / ˈ ɛ s k juː ˈ ɛ l / "S-Q-L"; [ 4 ] short for Structured Query Language ) is a special-purpose programming language designed for managing data held in a relational database management systems (RDBMS). Originally based upon relational algebra and tuple relational calculus , SQL consists of a data definition language and a data manipulation language . The scope of SQL includes data insert, query, update and delete , schema creation and modification, and data access control. Although SQL is often described as, and to a great extent is, a declarative language ( 4GL ), it also includes procedural elements.
SQL
The following is a list of algorithms along with one-line descriptions for each. [ edit ] Combinatorial algorithms [ edit ] General combinatorial algorithms [ edit ] Graph algorithms [ edit ] Graph drawing