Lesson 4: Loading Data – CSV, Excel, JSON & More

1. Loading CSV Files

CSV = Comma-Separated Values — most common ML data format.

df = pd.read_csv("iris.csv")
print(df.head())

Useful parameters:

• sep="," (default) or "\t" for tab
• header=0 (first row = columns) or None
• index_col="id" (use column as index)
• usecols=["name", "age"] (load only some columns)

2. Other Formats

• Excel: pd.read_excel("data.xlsx", sheet_name="Sheet1")
• JSON: pd.read_json("data.json")
• SQL: pd.read_sql("SELECT * FROM table", connection)
• Clipboard: pd.read_clipboard()

Common in ML: CSV for tabular data, JSON for API responses.