如何使用python重写CSV中的一行？

Question

I'm having some trouble with my code - I have a csv file and I have to save the first line in the csv as a list. Then I have to clear the file and rewrite the line using the list. This is my code:

import csv

f = open('PlateBook.csv','r')
reader = f.readlines()

for row in reader:
    outrow = list(row) 

    with open('PlateBook.csv', 'w', newline='') as fp:
        f.truncate
        a = csv.writer(fp, delimiter=',')
        data =  [outrow]

        a.writerows(data)

The trouble is, when I open the csv in Excel it's clearly wrong. Each character fills up a cell - I want the file to look exactly the same as when I written the file.

Answer 1

From the issue you describe, I guess that you don't want to do

outrow = list(row) 

which simply creates a list of each charater, but more something like

outrow = row.split(',')

which create a list of the string separated by commas.

Or, even better , use a csv.reader , so it handle quotes and all little details of csv's.

Here is an untested sample code of what you should do.

import csv

with open('PlateBook.csv','rt') as input_file:
    reader = csv.reader( input_file )
    with open('PlateBook.temp.csv','wt') as output_file:
        writer = csv.DictWriter( output_file, fieldnames = csvreader.fieldnames )
        writer.writeheader()
        for row in reader:
            writer.writerow( row )

#So far we didnot touch the original file, so if the process
#fails, nothing is left in half-processed state.
import os
os.remove( 'PlateBook.csv' )
os.rename( 'PlateBook.temp.csv', 'PlateBook.csv' )