Python 3:

with open('data.csv', 'a', newline='') as fp:
    for player in self.players:
        a = csv.writer(fp, delimiter=',');
        data = [[player.name, player.penalty(), player.score()]];
        a.writerows(data);

With python 3 there is change in the CSV module you can read here

Python 2.x:

Just change the open() to binary open('data.csv', 'ab')

You can set control quoting using:

csv.writer(fp, delimiter=',',quoting=csv.QUOTE_MINIMAL)

As from docs your options are:

csv.QUOTE_ALL Instructs writer objects to quote all fields.

csv.QUOTE_MINIMAL Instructs writer objects to only quote those fields which contain special characters such as delimiter, quotechar or any of the characters in lineterminator.

csv.QUOTE_NONNUMERIC Instructs writer objects to quote all non-numeric fields.

Instructs the reader to convert all non-quoted fields to type float.

csv.QUOTE_NONE Instructs writer objects to never quote fields. When the current delimiter occurs in output data it is preceded by the current escapechar character. If escapechar is not set, the writer will raise Error if any characters that require escaping are encountered.

with open('document.csv','a') as fd:
    fd.write(myCsvRow)

Opening a file with the 'a' parameter allows you to append to the end of the file instead of simply overwriting the existing content. Try that.

Python 3:

The official csv documentation recommends opening the file with newline='' on all platforms to disable universal newlines translation:

with open('output.csv', 'w', newline='', encoding='utf-8') as f:
    writer = csv.writer(f)
    ...

The CSV writer terminates each line with the lineterminator of the dialect, which is '\r\n' for the default excel dialect on all platforms because that's what RFC 4180 recommends.

Python 2:

On Windows, always open your files in binary mode ("rb" or "wb"), before passing them to csv.reader or csv.writer.

Although the file is a text file, CSV is regarded a binary format by the libraries involved, with \r\n separating records. If that separator is written in text mode, the Python runtime replaces the \n with \r\n, hence the \r\r\n observed in the file.

See this previous answer.

Are you using the pandas package? You do not mention that anywhere.

Pandas does not automatically append a new line, and I am not sure how to force it. But you can just do:

f.write('\n')
summaryDF.to_csv(path_or_buf=f, mode='a', ...)

An unrelated bug in your code:

You seem to have a global file object called f.

When you do this:

with open('test.csv', 'w+') as f:
    ...
    f.close()

The file that you are closing there is the file that you just opened in the with block. You are not closing the global file f because the variable was overshadowed by the f in that scope.

Is this what you want? Either way, it makes no sense. The reason why we use the with scope is to avoid having to close the file explicitly.

You either use:

f = open('filename')
...
f.close()

OR

with open('filename') as f:
    ...

You do not close a file opened within a with block. Using a with block has the additional advantage that the file gets closed even if an exception is raised and the following code is not executed.

While opening file use newline parameter, like below

with open("m.csv","a",newline='') as csvfile:

I had a similar problem and after a good bit of searching, I didn't find any simple/elegant solution. The minimal fix that worked for me is:

import pandas as pd

with open('foo.csv', 'a') as f:
    f.write('\n')    
mydf.to_csv('foo.csv', index = False, header = False, mode='a')

With some tinkering I realized you can add the following line to make sure you begin writing on a new line in a csv. Though it seems kind of hackish. Documentation mentions a lot about a kwarg newline='', but it wasn't recognized as valid.

writer.writerow([])

I also open with 'ab' parameter.

import csv
with open('mycsvfile.csv','ab') as f:
    writer=csv.writer(f)
    writer.writerow([])
    writer.writerow(['0','0','0'])

The csv.writer module directly controls line endings and writes \r\n into the file directly. In Python 3 the file must be opened in untranslated text mode with the parameters 'w', newline='' (empty string) or it will write \r\r\n on Windows, where the default text mode will translate each \n into \r\n.

#!python3
with open('/pythonwork/thefile_subset11.csv', 'w', newline='') as outfile:
    writer = csv.writer(outfile)

If using the Path module:

from pathlib import Path
import csv

with Path('/pythonwork/thefile_subset11.csv').open('w', newline='') as outfile:
    writer = csv.writer(outfile)

If using the StringIO module to build an in-memory result, the result string will contain the translated line terminator:

from io import StringIO
import csv

s = StringIO()
writer = csv.writer(s)
writer.writerow([1,2,3])
print(repr(s.getvalue()))  # '1,2,3\r\n'   (Windows result)

If writing that string to a file later, remember to use newline='':

# built-in open()
with open('/pythonwork/thefile_subset11.csv', 'w', newline='') as f:
    f.write(s.getvalue())

# Path's open()
with Path('/pythonwork/thefile_subset11.csv').open('w', newline='') as f:
    f.write(s.getvalue())

# Path's write_text() added the newline parameter to Python 3.10.
Path('/pythonwork/thefile_subset11.csv').write_text(s.getvalue(), newline='')

In Python 2, use binary mode to open outfile with mode 'wb' instead of 'w' to prevent Windows newline translation. Python 2 also has problems with Unicode and requires other workarounds to write non-ASCII text. See the Python 2 link below and the UnicodeReader and UnicodeWriter examples at the end of the page if you have to deal with writing Unicode strings to CSVs on Python 2, or look into the 3rd party unicodecsv module:

#!python2
with open('/pythonwork/thefile_subset11.csv', 'wb') as outfile:
    writer = csv.writer(outfile)

Documentation Links

• https://docs.python.org/3/library/csv.html#csv.writer
• https://docs.python.org/2/library/csv.html#csv.writer

This problem occurs only with Python on Windows.

In Python v3, you need to add newline='' in the open call per:

Python 3.3 CSV.Writer writes extra blank rows

On Python v2, you need to open the file as binary with "b" in your open() call before passing to csv

Changing the line

with open('stocks2.csv','w') as f:

to:

with open('stocks2.csv','wb') as f:

will fix the problem

More info about the issue here:

CSV in Python adding an extra carriage return, on Windows

change 'w' to 'a'

with open('outfile.csv','a')

The strip() method removes whitespace, including newlines.

fileout.writerow(line.strip())