使用 python 更新 csv 文件

Question

I am working on a small project,where one of the step is to write on a csv file a list of data. I am looping through a list,and fetching specific data and writing it to a csv. The problem is when the write operation is being processed it removes previous entries of the csv file.My csv writing method is as follows: and an example

def csv_writer(data_list,file_path):
    import csv
    file_p = open(file_path, "wb")
    write_pattern = csv.writer(file_p, delimiter=",", quotechar=",")
    write_pattern.writerow(data_list)
    file_p.close() 

An example data list is:

data_list = ['a', '', 'a', 'a', 'd', 'e']

And I am trying to have data in the file as follows:

a,,a,d,e
a,b,c,d,e
a,g.j,l,m

Thanks in advance.

Answer 1

Maybe open the file in append mode?

file_p = open(file_path, "ab")

Answer 2

When you open the file, try opening it for appending, like this.

def csv_writer(data_list,file_path):
    import csv
    file_p = open(file_path, "a")
    write_pattern = csv.writer(file_p, delimiter=",", quotechar=",")
    write_pattern.writerow(data_list)
    file_p.close() 

Answer 3

delimiter and quotechar must preferably be choosen as different

As I understood the question, the aim is to insert a new line before all the content of a CSV file. Here's the code to do that:

import csv

def csv_writer(data_list,file_path):
    file_p = open(file_path, "rb+")
    reader_pattern = csv.reader(file_p, delimiter=",", quotechar="$")
    write_pattern = csv.writer(file_p, delimiter=",", quotechar="$")

    content = list(reader_pattern)

    file_p.seek(0,0)
    write_pattern.writerow(data_list)
    write_pattern.writerows(content)
    file_p.truncate()
    file_p.close()


data_list = ['a', '', 'a', 'a', 'd', 'e']


csv_writer(data_list,'Copie de zozou.txt')