Add new lines to CSV file at each iteration in Python

Question

I have the following code in Python. I need to execute the function dd.save() N times, each time adding some new lines to the file test.csv. My current code just overrides the content of the file N times. How can I fix this issue?

def save(self):  

    f = csv.writer(open("test.csv", "w"))

    with open("test.csv","w") as f:
        f.write("name\n")
        for k, v in tripo.items():
            if v:
                f.write("{}\n".format(k.split(".")[0]))
                f.write("\n".join([s.split(".")[0] for s in v])+"\n")


if __name__ == "__main__":
    path="data/allData"

    entries=os.listdir(path)

    for i in entries:
      dd=check(dataPath=path,entry=i)
      dd.save()
      print(i)

possible duplicate of How do you append to a file in Python? — Open AI - Opting Out
– Open AI - Opting Out, Commented Mar 9, 2015 at 12:21
You need to open in append mode so with open("test.csv","wa") as f: — EdChum
– EdChum, Commented Mar 9, 2015 at 12:21

Yasel · Accepted Answer · 2022-01-18 19:16:17Z

4

The most commonly-used values of mode are 'r' for reading, 'w' for writing (truncating the file if it already exists), and 'a' for appending (which on some Unix systems means that all writes append to the end of the file regardless of the current seek position).

Open the file in append mode:

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

Check docs here.

edited Jan 18, 2022 at 19:16

answered Mar 9, 2015 at 12:25

Yasel

3,1684 gold badges42 silver badges49 bronze badges

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

Collectives™ on Stack Overflow

Add new lines to CSV file at each iteration in Python

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related