to_csv regression in 0.23.1

Writing to gzip no longer works with 0.23.1:

with gzip.open('test.txt.gz', 'wt') as f:
    pd.DataFrame([0,1],index=['a','b'], columns=['c']).to_csv(f, sep='\t')

produces corrupted output. This works fine in 0.23.0.

Presumably this is related to #21241 and #21118.

[saidie]

Hi, I also encountered a to_csv problem on 0.23.1 although my case is different to others:

import sys
import pandas as pd
df = pd.DataFrame([0,1])
df.to_csv(sys.stdout)

This code writes the dataframe to a file named <stdout> while it is expected to be printed out to the stdout.

[littleK0i]

@WillAyd , I did a quick research.

It seems that all “file-like” objects which cannot be converted to string file paths are affected. Gzip wrapper, stdout, FD’s - all these problems have the same origin.

Example with FD:

import pandas
import os

with os.fdopen(3, 'w') as f:
    print(f)
    pandas.DataFrame([0, 1]).to_csv(f)

Output:

<_io.TextIOWrapper name=3 mode='w' encoding='UTF-8'>
Traceback (most recent call last):
  File "gg.py", line 6, in <module>
    pandas.DataFrame([0, 1]).to_csv(f)
  File "/Users/wr/anaconda3/lib/python3.6/site-packages/pandas/core/frame.py", line 1745, in to_csv
    formatter.save()
  File "/Users/wr/anaconda3/lib/python3.6/site-packages/pandas/io/formats/csvs.py", line 166, in save
    f.write(buf)
AttributeError: 'int' object has no attribute 'write'

I guess, integer comes from “name” attribute of TextIOWrapper. For STDOUT it will be <stdout>, etc.