Group Data Helper Class in Python

class GroupData:
    """A simple helper class to store and group data for beginners."""

    def __init__(self):
        self.items = []

    def add(self, item, group):
        """Add an item under a given group name."""
        self.items.append({"item": item, "group": group})

    def get_groups(self):
        """Return a list of all unique group names."""
        return list({entry["group"] for entry in self.items})

    def items_in_group(self, group):
        """Return all items that belong to the given group."""
        return [entry["item"] for entry in self.items if entry["group"] == group]

    def group_counts(self):
        """Return a dictionary mapping each group to its item count."""
        counts = {}
        for entry in self.items:
            group = entry["group"]
            counts[group] = counts.get(group, 0) + 1
        return counts

    def __str__(self):
        """Human-readable summary of the grouped data."""
        lines = ["Grouped data:"]
        for group in self.get_groups():
            items = ", ".join(self.items_in_group(group))
            lines.append(f"  {group}: {items}")
        return "\n".join(lines)


if __name__ == "__main__":
    # Demonstrate usage with fruits and colors
    db = GroupData()
    db.add("apple", "fruit")
    db.add("banana", "fruit")
    db.add("carrot", "vegetable")
    db.add("red", "color")
    db.add("blue", "color")
    db.add("broccoli", "vegetable")

    print(db)
    print("\nGroups:", db.get_groups())
    print("Fruit items:", db.items_in_group("fruit"))
    print("Counts:", db.group_counts())