# Java DataFrame Engine

This project is a lightweight DataFrame library built in Java. It allows you to read data from CSV files, convert column types, group data by one or more columns, and perform aggregation operations like averaging.

The goal was to create a basic version of Python’s pandas library using custom-built data structures such as ArrayList, HashMap, and more. The project supports chaining methods like `readCsv()`, `mapValues()`, `groupBy()`, and `aggregate()`.

### Key Features
- Read and parse CSV files
- Convert column types (e.g., String to Integer)
- Group data using `groupBy()`
- Aggregate columns with custom functions
- Built entirely from scratch using Java

### Example Usage
```java
DataFrame df = new DataFrameImpl()
    .readCsv("resources/movies.csv")
    .mapValues("Rating", Integer::parseInt, String.class, Integer.class)
    .groupBy("Title")
    .aggregate(...);