subsetted

Subsetted is an adjective or past participle used to describe data, objects, or results that have been restricted to a subset of a larger set. In data analysis and computing, to subset something means to select a portion that satisfies specified criteria, or to project a larger set onto a smaller dimension. A subsetted data set contains fewer rows, columns, or elements than the original and is often used for exploration, testing, or visualization.

In programming languages and databases, subsetting is performed by filtering with conditions, indexing, slicing, or projection. Examples include boolean masks in Python’s pandas, which produce a subsetted DataFrame; the subset() function in R; or a SQL query that returns only the rows matching a WHERE clause and only the columns listed in the SELECT. Subsetting can be by rows, by columns, or by both. Materialized views or cached results can be described as subsetted representations when they store a subset of a larger dataset for faster access.

Cautions: Subsetting introduces potential biases if the selection criteria are not representative. Nonrandom subsetting can distort conclusions; improper subsetting can lead to data leakage in model evaluation. Clear documentation of the criteria used is recommended; when reproducibility matters, a reproducible script or query should define the subset operation.