Writing CSV in Python

DictWriter takes rows as dicts and writes the header for you.

import csv
from io import StringIO

rows = [
    {"lang": "python", "tpm": 104, "stars": 3},
    {"lang": "rust", "tpm": 98, "stars": 3},
]

buffer = StringIO()
writer = csv.DictWriter(buffer, fieldnames=["lang", "tpm", "stars"],
                        extrasaction="ignore")
writer.writeheader()
writer.writerows(rows)

print(buffer.getvalue())
print(list(csv.DictReader(StringIO(buffer.getvalue())))[0])

How it works

1. newline= empty is required, or you get blank lines on Windows.
2. writeheader emits the field names once.
3. extrasaction decides what to do with keys you did not declare.

Keywords and builtins used here

• list
• print

The run, in numbers

Lines

16

Characters to type

374

Tokens

130

Three-star pace

105 tpm

At the three-star pace of 105 tokens a minute, this run takes about 74 seconds.

Type this snippet

Step 4 of 4 in Files & archives, step 29 of 41 in Domain tools.

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