6. DataFrames

1. The Table

A DataFrame is a collection of Series sharing a common Index. Think of it as an In-Memory SQL Table or a super-charged Excel sheet.

2. Access: Loc vs Iloc

This confuses everyone. Memorize this:

• .loc: Location by Label (Name). "Find row 'Index-2023'".
• .iloc: Integer Location. "Find row 0".

python
df.loc['2023-01-01', 'Revenue'] # Row Label, Col Label
df.iloc[0, 1]                    # Row 0, Col 1