write in pandas row wise

user_9936581 0
Viewed 558

My code:

if __name__ == "__main__":
    while True:
        df = pd.read_csv('test - Sheet1 (6).csv') 

        for index, row in df.iterrows():
            df['new']=preprocessing(row['prev'])
        df.to_csv('today.csv',header=False)

I have some values in my CSV file like this in prev column-

prev
ABC
Abc
BaC

I have pre-processing function that will change the column something like this-

new
abc
abc
bac

But when I am writing it to CSV file, the output I am getting is -

prev new
ABC bac
Abc bac
BaC bac

it's only storing the last row value. How do I make it like this-

prev new
ABC abc
Abc abc
BaC bac
pandas csv python
1 Answers

Instead of the loop, just use apply:

df = pd.read_csv('test - Sheet1 (6).csv') 

df['new'] = row['prev'].apply(preprocessing)
df.to_csv('today.csv', header=False)

Iterating through and assigning assigns to the whole column at once, not to that specific index, if you want iterrows try:

df = pd.read_csv('test - Sheet1 (6).csv') 
for index, row in df.iterrows():
    df.loc[index, 'new'] = preprocessing(row['prev'])
df.to_csv('today.csv', header=False)
user_87083640
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