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In computer science, a lookup table (LUT) is an array that replaces runtime computation of a mathematical function with a simpler array indexing operation, in a process termed as direct addressing. The savings in processing time can be significant, because retrieving a value from memory is often faster than carrying out an "expensive ...
A MapCollection is a mixin class that defines the basic set of methods implemented by all collections that map from an index to a value. The Directory, StringTable, IdentityTable, Properties, Table, Relation and Stem classes inherit these methods. [31] A Directory or a StringTable object is a collection of unique string indexes.
Note how the use of A[i][j] with multi-step indexing as in C, as opposed to a neutral notation like A(i,j) as in Fortran, almost inevitably implies row-major order for syntactic reasons, so to speak, because it can be rewritten as (A[i])[j], and the A[i] row part can even be assigned to an intermediate variable that is then indexed in a separate expression.
The Z-ordering can be used to efficiently build a quadtree (2D) or octree (3D) for a set of points. [4] [5] The basic idea is to sort the input set according to Z-order.Once sorted, the points can either be stored in a binary search tree and used directly, which is called a linear quadtree, [6] or they can be used to build a pointer based quadtree.
A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes and storage space to maintain the index data structure. Indexes are used to quickly locate data without having to search every row in a database table every time said table is accessed.
Tagging allows indexing codes to be embedded in the text after the indexing is complete. The indexer inserts numbered dummy tags in the files, and then builds the index separately; Many word processors and desktop publishing software have integrated automated indexing functions. These tools build a concordance or word lists from processed files.
Power Pivot expands on the standard pivot table functionality in Excel. In the Power Pivot editor, relationships can be established between multiple tables to effectively create foreign key joins . Power Pivot can scale to process very large datasets in memory, which allows users to analyze datasets that would otherwise surpass Excel's limit of ...
The index is similar to the term document matrices employed by latent semantic analysis. The inverted index can be considered a form of a hash table. In some cases the index is a form of a binary tree, which requires additional storage but may reduce the lookup time.