Python: Use Csv Reader With Single File Extracted From Tarfile

I am trying to use the Python CSV reader to read a CSV file that I extract from a .tar.gz file using Python's tarfile library. I have this: tarFile = tarfile.open(name=tarFileName,

Solution 1:

tarfile.extractfile returns an io.BufferedReader object, a bytes stream, and yet csv.reader expects a text stream. You can use io.TextIOWrapper to convert the bytes stream to a text stream instead:

import io

...

reader = csv.reader(io.TextIOWrapper(tarredCSV, encoding='utf-8'))

Solution 2:

You need to provide a file-like object to csv.reader.

Probably the best solution, without having to consume a complete file at once is this approach (thanks to blhsing and damon for suggesting it):

import csv
import io
import tarfile

tarFile = tarfile.open(name=tarFileName, mode="r")
for file in tarFile.getmembers():
    csv_file = io.TextIOWrapper(tarFile.extractfile(file), encoding="utf-8")

    reader = csv.reader(csv_file)
    next(reader)    # skip headerfor row in reader:
        print(row)

Alternatively a possible solution from here: Python3 working with csv files in tar files would be

import csv
import io
import tarfile

tarFile = tarfile.open(name=tarFileName, mode="r")
for file in tarFile.getmembers():
    csv_file = io.StringIO(tarFile.extractfile(file).read().decode('utf-8'))

    reader = csv.reader(csv_file)
    next(reader)    # skip headerfor row in reader:
        print(row)

Here a io.StringIO object is used to make csv.reader happy. However, this might not scale well for larger files contained in the tar as each file is read in one single step.