How to write to CSV using csv package in python line by line

Question

I want to write data to a csv file row by row :

Please find the code below:

with open('a.csv',mode='w') as csv_file:
    fieldnames=['colA','colB','colC']
    writer=csv.DictWriter(csv_file,fieldnames=fieldnames)
    writer.write_row({'colA':data1,'colB':data2,'colC':data3})

The above code is inside a loop in which the data changes each time and i need to write to csv file in every loop. With this code my csv file is having only 1 line with the latest data. How do i modify the code to get multiple lines?

Answer 1

You're recreating the file and reinitializing the csv on each iteration. Instead, move the initialization outside the loop so that it only happens once.

with open('a.csv',mode='w') as csv_file:
    fieldnames=['colA','colB','colC']
    writer=csv.DictWriter(csv_file,fieldnames=fieldnames)
    for line in lines: # This is where your `for` loop should be relative to `with`
        writer.write_row({'colA':data1,'colB':data2,'colC':data3})