Avoiding the phenomenon that blank lines are inserted when outputting Python CSV

Introduction

When I try to output CSV from Python on Windows, a blank line is inserted for each line, so I leave a workaround.

`Output CSV`


a,b,c

d,e,f

g,h,i

environment

Windows 10
Python 3.7

Code in question


import csv

with open("./test.csv", "w") as f:
    writer = csv.writer(f)
    writer.writerow(["a", "b", "c"])
    writer.writerow(["d", "e", "f"])
    writer.writerow(["g", "h", "i"])

solution

I don't remember becoming a Mac and Linux, so I thought it was a problem with the Windows environment. It is thought that CRLF has an effect, so we will try to avoid CRLF.

Specify an empty string in the argument newline of the open function
Specify the line feed code in the argument lineterminator of the writer function.

open: newline An argument that specifies the conversion destination of the line separator. If not specified, it will be converted to the system default line feed. In the case of Windows, it is CRLF, but since a blank line will occur, specify '' or \ n. If you specify'' or'\ n', the conversion will not be performed and the output will be as is.


import csv

with open("./test.csv", "w", newline="") as f:
    writer = csv.writer(f)
    writer.writerow(["a", "b", "c"])
    writer.writerow(["d", "e", "f"])
    writer.writerow(["g", "h", "i"])

writer: lineterminator An argument to represent the end of each line. The default is \ r \ n, so specify \ n.


with open("./test.csv", "w") as f:
    # writer = csv.writer(f)
    writer = csv.writer(f, lineterminator="\n")
    writer.writerow(["a", "b", "c"])
    writer.writerow(["d", "e", "f"])
    writer.writerow(["g", "h", "i"])

Remarks

In the case of python2.7, there is no newline, so I think it will be a way to use the lineterminator of csv.writer. If it is io.open, there is a newline argument, but the character string to be written is caught around encoding and I have not investigated it in detail.

reference

https://qiita.com/ryokurta256/items/defc553f5165c88eac95 Python: open: newline Python: csv: lineterminator