Writing to CSV from String or List

Introduction#

Writing to a .csv file is not unlike writing to a regular file in most regards, and is fairly straightforward. I will, to the best of my ability, cover the easiest, and most efficient approach to the problem.

Parameters#

Parameter	Details
open (“/path/”, “mode”)	Specify the path to your CSV file
open (path, “mode”)	Specify mode to open file in (read, write, etc.)
csv.writer(file, delimiter)	Pass opened CSV file here
csv.writer(file, delimiter=’ ’)	Specify delimiter character or pattern
## Remarks#

open( path, "wb")

"wb" - Write mode.

The b parameter in "wb" we have used, is necessary only if you want to open it in binary mode, which is needed only in some operating systems like Windows.

csv.writer ( csv_file, delimiter=',' )

Here the delimiter we have used, is ,, because we want each cell of data in a row, to contain the first name, last name, and age respectively. Since our list is split along the , too, it proves rather convenient for us.

Basic Write Example

import csv

#------ We will write to CSV in this function ------------

def csv_writer(data, path):
    
    #Open CSV file whose path we passed.
    with open(path, "wb") as csv_file:
        
        writer = csv.writer(csv_file, delimiter=',')
        for line in data:
            writer.writerow(line)



#---- Define our list here, and call function ------------

if __name__ == "__main__":

    """
    data = our list that we want to write. 
    Split it so we get a list of lists.
    """
    data = ["first_name,last_name,age".split(","),
            "John,Doe,22".split(","),
            "Jane,Doe,31".split(","),
            "Jack,Reacher,27".split(",")
            ]

    # Path to CSV file we want to write to.
    path = "output.csv"
    csv_writer(data, path)

Appending a String as a newline in a CSV file

def append_to_csv(input_string):
    with open("fileName.csv", "a") as csv_file:
        csv_file.write(input_row + "\n")