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  2. Map (higher-order function) - Wikipedia

    en.wikipedia.org/wiki/Map_(higher-order_function)

    Therefore, compilers will attempt to transform the first form into the second; this type of optimization is known as map fusion and is the functional analog of loop fusion. [2] Map functions can be and often are defined in terms of a fold such as foldr, which means one can do a map-fold fusion: foldr f z . map g is equivalent to foldr (f .

  3. Wide and narrow data - Wikipedia

    en.wikipedia.org/wiki/Wide_and_narrow_data

    The pandas package in Python implements this operation as "melt" function which converts a wide table to a narrow one. The process of converting a narrow table to wide table is generally referred to as "pivoting" in the context of data transformations.

  4. Data transformation (computing) - Wikipedia

    en.wikipedia.org/wiki/Data_transformation...

    Code generation is the process of generating executable code (e.g. SQL, Python, R, or other executable instructions) that will transform the data based on the desired and defined data mapping rules. [4] Typically, the data transformation technologies generate this code [5] based on the definitions or metadata defined by the developers.

  5. Set operations (SQL) - Wikipedia

    en.wikipedia.org/wiki/Set_operations_(SQL)

    Set operations in SQL is a type of operations which allow the results of multiple queries to be combined into a single result set. [ 1 ] Set operators in SQL include UNION , INTERSECT , and EXCEPT , which mathematically correspond to the concepts of union , intersection and set difference .

  6. List of data structures - Wikipedia

    en.wikipedia.org/wiki/List_of_data_structures

    String, a sequence of characters representing text; Union, a datum which may be one of a set of types; Tagged union (also called a variant, discriminated union or sum type), a union with a tag specifying which type the data is

  7. Data type - Wikipedia

    en.wikipedia.org/wiki/Data_type

    The standard type hierarchy of Python 3. In computer science and computer programming, a data type (or simply type) is a collection or grouping of data values, usually specified by a set of possible values, a set of allowed operations on these values, and/or a representation of these values as machine types. [1]

  8. Pointer (computer programming) - Wikipedia

    en.wikipedia.org/wiki/Pointer_(computer_programming)

    A basic example is in the argv argument to the main function in C (and C++), which is given in the prototype as char **argv—this is because the variable argv itself is a pointer to an array of strings (an array of arrays), so *argv is a pointer to the 0th string (by convention the name of the program), and **argv is the 0th character of the ...

  9. String (computer science) - Wikipedia

    en.wikipedia.org/wiki/String_(computer_science)

    Most strings in modern programming languages are variable-length strings. Of course, even variable-length strings are limited in length – by the size of available computer memory. The string length can be stored as a separate integer (which may put another artificial limit on the length) or implicitly through a termination character, usually ...

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    python dataframe apply map to set string variable value in sql example statement