DFLib ("DataFrame Library") is a lightweight pure Java implementation of a common DataFrame data structure. DataFrames exist in Python (pandas), R, Spark and other languages and frameworks. DFLib's DataFrame is specifically intended for Java and JVM languages.

With DataFrame API, you get essentially the same data manipulation capabilities you may be used to in SQL (such as joins, etc.), only you apply them in-memory and over dynamically defined "tables". While SQL is "declarative", DataFrame allows step-by-step transformations that are somewhat easier to understand and much easier to compose.

DataFrame is extremely versatile and can be used to model a variety of data tasks. ETL, log analysis, spreadsheets processing are just some of the examples. DFLib comes with connectors for many data formats: CSV, Excel, RDBMS, Avro, JSON and can be easily adapted to other formats (e.g. web-service-based ones like Google Sheets, etc.)

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• DataFrame, a Swiss Army Knife of Java Data Processing, Nashville JUG, 03/2024
• Early version of DFLib, Frankfurt WO Day, 04/2019