Python CSV: Reading and Writing Spreadsheet Data

Reading a CSV

import csv
with open("scores.csv") as f:
    reader = csv.reader(f)
    for row in reader:
        print(row)

With Headers — DictReader

with open("scores.csv") as f:
    reader = csv.DictReader(f)
    for row in reader:
        print(row["name"], row["score"])

Writing a CSV

rows = [
    ["name", "score"],
    ["Ming", 85],
    ["Amy", 92],
]
with open("out.csv", "w", newline="") as f:
    writer = csv.writer(f)
    writer.writerows(rows)

Handling Special Characters

If your data contains commas or quotes, csv.writer automatically quotes them — do not try to hand-roll CSV output.

Reading Large Files

CSV readers stream row-by-row, so they work on very large files without loading everything into memory.