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Python 101: Interactively learn how to program with Python 3

Writing a CSV File

Writing a CSV file in python

We'll cover the following...

The csv module also has two methods that you can use to write a CSV file. You can use the writer function or the DictWriter class. We’ll look at both of these as well. We will be with the writer function. Let’s look at a simple example:

Python 3.5
import csv
def csv_writer(data, path):
    """
    Write data to a CSV file path
    """
    with open(path, "w", newline='') as csv_file:
        writer = csv.writer(csv_file, delimiter=',')
        for line in data:
            writer.writerow(line)
if __name__ == "__main__":
    data = ["first_name,last_name,city".split(","),
            "Tyrese,Hirthe,Strackeport".split(","),
            "Jules,Dicki,Lake Nickolasville".split(","),
            "Dedric,Medhurst,Stiedemannberg".split(",")
            ]
    path = "output.csv"
    csv_writer(data, path)
    
    # You are welcome to apply the CSV Reading
    # code that you learned in the previous lesson
    # and read the CSV file again. 
    # Make sure, it outputs what you just wrote.

In the code above, we create a csv_writer function that accepts two arguments: data and path. The data is a list of lists that we create at the bottom of the script. We use a shortened version of the data from the previous example and split the strings on the comma. This returns a list. So we end up with a nested list that looks like this:

Python 3.5
[['first_name', 'last_name', 'city'],
 ['Tyrese', 'Hirthe', 'Strackeport'],
 ['Jules', 'Dicki', 'Lake Nickolasville'],
 ['Dedric', 'Medhurst', 'Stiedemannberg']]

The csv_writer function opens the path that we pass in and ...