Inline CSV File Editing with Python

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No, you should not attempt to write to the file you are currently reading from. You can do it if you keep seeking back after reading a row but it is not advisable, especially if you are writing back more data than you read.

The canonical method is to write to a new, temporary file and move that into place over the old file you read from.

from tempfile import NamedTemporaryFile
import shutil
import csv

filename="tmpEmployeeDatabase.csv"
tempfile = NamedTemporaryFile('w+t', newline="", delete=False)

with open(filename, 'r', newline="") as csvFile, tempfile:
    reader = csv.reader(csvFile, delimiter=",", quotechar=""")
    writer = csv.writer(tempfile, delimiter=",", quotechar=""")

    for row in reader:
        row[1] = row[1].title()
        writer.writerow(row)

shutil.move(tempfile.name, filename)

I’ve made use of the tempfile and shutil libraries here to make the task easier.

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