Standard Library

CSV Data

csv reads and writes row-shaped text data.

DictReader uses the header row as dictionary keys. The values are still strings because CSV is text.

Source

import csv
import io

text = "name,score\nAda,98\nGrace,95\n"
rows = list(csv.DictReader(io.StringIO(text)))

print(rows[0])
print(type(rows[0]["score"]).__name__)

Output

{'name': 'Ada', 'score': '98'}
str

Convert numeric fields at the boundary where the program leaves CSV text and starts doing arithmetic.

Source

print(sum(int(row["score"]) for row in rows))

Output

DictWriter turns dictionaries back into row-shaped text with the same column order.

Source

output = io.StringIO(newline="")
writer = csv.DictWriter(output, fieldnames=["name", "passed"])
writer.writeheader()
writer.writerow({"name": "Ada", "passed": True})

print(output.getvalue().splitlines()[1])

Output

Ada,True

Notes

Let csv handle quoting and delimiters instead of calling split(",").
CSV fields are text until your code converts them.
Reach for JSON when records need nested lists, dictionaries, booleans, or numbers that preserve their type.

Run the complete example

Expected output

{'name': 'Ada', 'score': '98'}
193
Ada,True

Execution time appears here after you run the example.

CSV Data

See also

Run the complete example

Example code

Expected output