pData

pData is a term used across computing and data science with different meanings depending on context. In general, it is often used as an abbreviation in identifiers to denote a pointer to data, or a data object associated with something (private data, per-object data). It is not a formal standard, so its exact meaning varies by project.

In the Bioconductor project for R, pData is a standard accessor function for phenotypic data associated with genomic data objects. For example, in ExpressionSet objects, the phenotypic data (sample metadata, such as treatment group, batch, or clinical attributes) are stored in a phenotypic data slot and can be retrieved with pData(object). The result is typically a data frame-like structure that can be manipulated with typical data frame operations. The pData function may also be used to assign or update metadata.

In other contexts, pData is simply a variable name used by programmers to refer to a pointer to data or to per-object data. The exact interpretation depends on the programming language and the codebase, and is not standardized across ecosystems.

When encountering pData, it is advisable to consult the local documentation or code comments to understand its intended meaning in that specific project. This ensures correct usage, whether it refers to a data accessor, a pointer to data, or a per-object data field.