Python’s csv Module provides the csv.writer() object to write a list into a CSV file. This object provides a writerow() method that writes a single row, whereas its writerows() method writes multiple rows.

The primary purpose of this conversion is to save list-based data (e.g., lists of lists, dictionaries, or simple lists) into a text file, where each row represents an entry and columns are separated by commas (or other delimiters).

Single Flat List to CSV

If the input is a flat list, and you want to convert it into a CSV, the resulting file will be a single-column CSV. It is helpful for simple data, such as item names or IDs.

import csv


# Convert a flat list into a single-column CSV.
simple_list = ['apple', 'banana', 'orange']
with open('simple_list.csv', 'w', newline='') as f:
    writer = csv.writer(f)
    for item in simple_list:
        writer.writerow([item])

Here is the output simple_list.csv file:

The output is a single-column CSV file, where the first value in each column is the header and the subsequent values follow.

Each list item is written as a row with one column. `newline=”` prevents extra blank lines in Windows.

List of Lists to CSV

Each inner list represents a row with multiple columns, ideal for tabular data.

The writerows() method is efficient for writing multiple rows.

import csv

# Column names
column_names = ["Character Name", "Series Name", "Age"]

# Data rows
rows = [["Mando", "Mandalorian", 35],
        ["Grogu", "Mandalorian", 50],
        ["Eleven", "Stranger Things", 14],
        ["Jon", "Game of Thrones", 30],
        ["Ross", "Friends", 35]]

# Crafting a CSV file for writing
with open('showdata.csv', 'w') as f:
    write = csv.writer(f)
    write.writerow(column_names)
    write.writerows(rows)

print("List has been written to 'showdata.csv'")

# Output: List has been written to 'showdata.csv'

Here is the saved showdata.csv file:

List of Dictionaries to CSV

If the input list contains different dictionaries, you can use the dictionary keys as headers, which is perfect for structured data, such as JSON-like objects.

Use the csv’s DictWriter() method to simplify header and row writing.

import csv


def dict_to_csv():

    data = [
        {'name': 'Krunal', 'age': 32, 'city': 'New York'},
        {'name': 'Ankit', 'age': 30, 'city': 'London'},
        {'name': 'Rushabh', 'age': 33, 'city': 'Tokyo'}
    ]

    with open('dict_people.csv', 'w', newline='', encoding='utf-8') as file:
        fieldnames = ['name', 'age', 'city']
        writer = csv.DictWriter(file, fieldnames=fieldnames)

        writer.writeheader()  # Write column headers
        writer.writerows(data)

    print("Dictionary data written to dict_people.csv")


dict_to_csv()

# Output: Dictionary data written to dict_people.csv

Empty List

If the list is empty, the output CSV file will also be empty. It will be created, but there won’t be any content.

import csv

data = []

with open("empty.csv", "w", newline='') as f:
    writer = csv.writer(f)
    writer.writerows(data)  # Writes nothing

print("Empty CSV file created successfully.")

# Output: Empty CSV file created successfully.

Missing values

If the list contains missing or empty values, such as None, the output CSV file will have empty fields.

import csv

list_with_missing = [['Kaynes Tech', 5782],
                     ['RR', None],
                     [None, 1431]]

with open('missing_values.csv', 'w', newline='') as f:
    writer = csv.writer(f)
    writer.writerow(['Name', 'Age'])
    writer.writerows(list_with_missing)

print("CSV file with missing values created successfully.")

# Output: CSV file with missing values created successfully.

Unicode and Non-ASCII Characters

The csv.writer.writerow() method supports non-ASCII characters (e.g., UTF-8 encoding).

import csv

unicode_list = [['José', 25],
                ['Müller', 30]]

with open('unicode_list.csv', 'w', newline='', encoding='utf-8') as f:
    writer = csv.writer(f)
    writer.writerow(['Name', 'Age'])
    writer.writerows(unicode_list)

print("CSV file with Unicode characters created successfully.")

# Output: CSV file with Unicode characters created successfully.

Pandas to_csv() method

If the input is a list and a dictionary, first, convert the list to a DataFrame and then use the to_csv() function to convert the DataFrame into a CSV file.

import pandas as pd

char_name = ["Mando", "Grogu", "Eleven", "Jon", "Ross"]
series_name = ["Mandalorian", "Mandalorian",
               "Stranger Things", "Game of Thrones", "Friends"]
age = [35, 50, 14, 30, 35]

dict = {"Character Name": char_name,
        "Series Name": series_name,
        "Age": age}

# Convert the dictionary to a Pandas DataFrame
df = pd.DataFrame(dict)

# Save the DataFrame to a CSV file
df.to_csv('dataframe.csv', index=False)

print("List has been written to '.csv'")

# Output: List has been written to '.csv'

That’s all!

Krunal Lathiya

With a career spanning over eight years in the field of Computer Science, Krunal’s expertise is rooted in a solid foundation of hands-on experience, complemented by a continuous pursuit of knowledge.