Read text file

Get a single str.

with open(path) as f_in:
    text = f_in.read()

Get a list of str objects.

with open(path) as f_in:
    text = f_in.read()
    lines = text.splitlines()

Note list.splitlines will remove newlines by default and something similar could be achived with list.split("\n")

Use f.seek(0) to reset if you need to read the entire file multiple times.

Read line by line. This is more memory efficient.

with open(path) as f_in:
    for line in f_in:
        print(line)

Write text file

with open(path, 'w') as f_out:
    f_out.write('foo\n')
    f_out.write('bar\n')

my_list = ["foo", "bar"]
with open(path, 'w') as f_out:
    f_out.writelines(my_list)

Example path values:

  • text.txt
  • foo/bar.txt
  • An absolute path

Write JSON file

with open(path, 'w') as f_out:
    json.dump(data, f_out)

Write CSV file

header = ["Foo", "Bar"]
rows = [["foo", "bar"], ["fizz", "buzz"]]
with open(path, 'w') as f_out:
    writer = csv.writer(f_out)
    write.writerow(header)
    write.writerows(rows)

header = ["Foo", "Bar"]
rows = [
    {"Foo": "a", "Bar" 1},
    {"Foo": "b", "Bar": 2}
}
with open(path, 'w') as f_out:
    writer = csv.DictWriter(f_out, fieldnames=header)
    write.writeheader()
    write.writerows(rows)