datajoukon

Datajoukon is a term used in data science to refer to a data condition, or predicate, applied to a dataset to select a subset of records. In practice, a datajoukon specifies a boolean expression over the attributes of the data, and a record is included in the subset if the expression evaluates to true.

Origin and usage context: the term combines "data" with "joukon," the Japanese word for condition. In English-speaking contexts this concept is usually described as a filter predicate or selection criterion. Datajoukon is central to operations that restrict data to those items meeting specific criteria.

Applications and examples: datajoukon are used in querying databases (the WHERE clause in SQL), data processing pipelines, and programming libraries that support filtering (such as data frames and streaming tools). Examples include selecting records where age >= 18 and country = 'Japan', or where price < 1000 or category = 'sale'. A datajoukon can be simple or a logical combination of multiple conditions, and it may involve functions or handling of missing values.

Considerations: efficiency and performance are important, as predicates can be pushed down to storage layers or optimized for faster evaluation. Correctness and interpretability matter to ensure the subset matches intended constraints. Representation often takes the form of boolean masks or predicate functions, and complex datajoukon may be combined with transformations or aggregations.

See also: predicate, filter, query, SQL WHERE, boolean algebra.