TypeError: a bytes-like object is required, not 'str' when trying to write in csv file

Question

I have to convert the followin code written in Python 2 to Python3:

with open('C:/path_to_csv_file/fold1_1.csv', 'wb') as csvfile:
    spamwriter = csv.writer(csvfile, delimiter=',', quotechar='|', quoting=csv.QUOTE_MINIMAL)
    for row, timeseq in izip(fold1, fold1_t):
        spamwriter.writerow([unicode(s).encode("utf-8") +'#{}'.format(t) for s, t in izip(row, timeseq)])

My Python 3 code is the following:

with open('C:/Users/path_to_csv_file/fold1_1.csv', 'wb') as csvfile:
    spamwriter = csv.writer(csvfile, delimiter=',', quotechar='|', quoting=csv.QUOTE_MINIMAL)
    for row, timeseq in zip(fold1, fold1_t): 
        for s, t in zip(row, timeseq):
            bytes_var = s.encode('utf-8') +'#{}'.format(t).encode('utf-8') 
            spamwriter.writerow(bytes_var)

fold1 contains:

fold1 = ['¢©§','¢©§','¢©§']

fold1_t contains:

fold1_t =[[0, 15, 173999],[0, 457325, 306],[0, 62954, 432]]

When I try to execute the code above I get the following error:

TypeError: a bytes-like object is required, not 'str'

The variable bytes_var is type of bytes so normally it should work. Have I done something wrong with the conversion from Python2 to Python3 to get that error? Thank you.

What line is the exception being thrown on?

SpoonMeiser
– SpoonMeiser

2020-12-08 13:02:40 +00:00
Commented Dec 8, 2020 at 13:02 — SpoonMeiser
– SpoonMeiser, Commented Dec 8, 2020 at 13:02
@SpoonMeiser At: spamwriter.writerow(bytes_var)

C96
– C96

2020-12-08 13:03:35 +00:00
Commented Dec 8, 2020 at 13:03 — C96
– C96, Commented Dec 8, 2020 at 13:03

Serge Ballesta · Accepted Answer · 2020-12-08 13:12:23Z

1

The csv module is one of the pieces where the conversion Python2 -> Python3 is not really straightforward. The underlying file is expected to be opened as text and no longer as a binary file, but with empty end of lines.

So I would write:

with open('C:/path_to_csv_file/fold1_1.csv', 'w', newline='', encoding='utf-8') as csvfile:
    spamwriter = csv.writer(csvfile, delimiter=',', quotechar='|', quoting=csv.QUOTE_MINIMAL)
    for row, timeseq in izip(fold1, fold1_t):
        spamwriter.writerow([s +'#{}'.format(t) for s, t in izip(row, timeseq)])

The current error is caused by the csv module sending a unicode string while the undelying file expected bytes.

answered Dec 8, 2020 at 13:12

Serge Ballesta

150k13 gold badges137 silver badges267 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Red · Accepted Answer · 2020-12-08 13:22:43Z

1

You'll need to change your wb to w. Also, in python 3, you can do formatted strings by directly passing the expression into the curly braces of the string, so the

s.encode('utf-8') +'#{}'.format(t).encode('utf-8')

can be

f'{s}#{t}'.encode('utf-8')

Altogether:

import csv

fold1 = ['¢©§','¢©§','¢©§']
fold1_t =[[0, 15, 173999], [0, 457325, 306], [0, 62954, 432]]

with open('C:/path_to_csv_file/fold1_1.csv', 'w') as csvfile:
    spamwriter = csv.writer(csvfile, delimiter=',', quotechar='|', quoting=csv.QUOTE_MINIMAL)
    for row, timeseq in zip(fold1, fold1_t): 
        for s, t in zip(row, timeseq):
            bytes_var = s.encode('utf-8') + f'#{t}'.encode('utf-8') 
            spamwriter.writerow(bytes_var)

edited Dec 8, 2020 at 13:22

answered Dec 8, 2020 at 13:08

Red

27.7k8 gold badges44 silver badges63 bronze badges

6 Comments

C96 Over a year ago

Thank you for your response. The code gets executed like that, but 'w' isn't different from 'wb' ?

Red Over a year ago

@C96 What do you mean?

C96 Over a year ago

Please correct me if I am wrong but the file would not contain different information if I open it in binary mode with 'wb' instead of 'w' ?

Red Over a year ago

@C96 Can you show me what the file will contain when you run the python 2 code?

C96 Over a year ago

For example that is the first line of fold1_1 b'\xc2\xa2#0',b'\xc2\xa9#15',b'\xc2\xa7#173999'

|

Collectives™ on Stack Overflow

TypeError: a bytes-like object is required, not 'str' when trying to write in csv file

2 Answers 2

Comments

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related