Python：保存到 CSV 文件，手动打开文件后意外写入下一列而不是行

Question

I've noticed a really weird bug and didn't know if anyone else had seen this / knows how to stop it.

I'm writing to a CSV file using this:

def write_to_csv_file(self, object, string):
        with open('data_model_1.csv', 'a') as f:
            writer = csv.writer(f)
            writer.writerow([object, string])

and then write to the file:

self.write_to_csv_file(self.result['outputLabel'], string)

If I open the CSV file to look at the results, the next time I write to the file, it will start in column 3 of the last line (column 1 is object, column 2 is string).

If I run self.write_to_csv_file(self.result['outputLabel'], string) multiple times without manually opening the file (obviously I open the file in the Python script), everything is fine.

It's only when I open the file so I get the issue of starting on Column 3.

Any thoughts on how to fix this?

Answer 1

You're opening the file in a ppend mode , so the data is appended to the end of the file. If the file doesn't end in a newline, rows may get concatenated. Try writing a newline to the file before appending new rows:

with open("data_model_1.csv", "a") as f:
    f.write("\n")