Python Program to Write List to File

In this Python tutorial, we will discuss how to write list to file in Python using different examples.

There are five methods to write a list to file in Python, which are shown below:

  1. Using a for loop and the write() method
  2. Using the writelines() method
  3. Using the join() and the write() method
  4. Using the JSON module
  5. Using the pickle

How Python Write List to File

One common task is writing a list to a file, which can be useful for storing data that can be read later or for sharing data with other programs. There are several methods for writing a list to a file in Python, including using a for loop, the writelines() method, json module, etc.

Method-1: Python Write List to File using a for loop and the write() method

In this method, we use a for loop to iterate through each item in the list, and use the write() method to write each item to the file. We also add a newline character ‘\n’ after each item to write each item on a new line.

# create a list of numbers
my_list = [1, 2, 3, 4, 5]


# open a file named "output.txt" in write mode
with open('output.txt', 'w') as f:


# loop through the list and write each item to the file
    for item in my_list:
        f.write(str(item) + '\n')

The code writes the elements of the list my_list to a file named output.txt, with each element on a new line. It uses the with statement to open the file in write mode and automatically close it after writing the data.

  • The for loop iterates over each element in the list and writes it to the file as a string, followed by a newline character to create a new line for the next element.
READ:  Pandas iterrows update value in Python [4 Ways]

Read: Python list methods

Method-2: Python Write List to File using the writelines() method

In this method, we use the writelines() method to write each item in the list to the file.

# create a list of mobile phone brands
mobile = ['samsung', 'redmi', 'oneplus']

# open a file named "f1.txt" in write mode
file = open('f1.txt', 'w')

# loop through the mobile phone list and write each item to the file
for item in mobile:
    file.writelines([item])

# close the file
file.close()

The above code creates a list of mobile phone brands and then opens a file named “f1.txt” in write mode. It then loops through the list and writes each item to the file using the writelines() method. Finally, it closes the file.

Python write a list to file using the writelines method
Python write a list to file using the writelines method

Read: Python concatenate list

Method-3: Python Write List to File using the join() and the write() method

In this method, we use the join() method to concatenate all the items in the list into a single string, separated by newline characters ‘\n’. We then use the write() method to write this string to the file.

# Define a list containing different types of values
my_list = ["USA", 2, 3, 4, 5]

# Open a file named 'join.txt' in write mode using a context manager
# and write the contents of the list to the file in a specific format
with open('join.txt', 'w') as f:
    f.write('\n'.join(map(str, my_list)))

The above code defines a list called my_list containing various data types. It then uses the with a statement to open a new file called ‘join.txt’ in write mode and writes the contents of my_list to the file, with each element on a new line.

Read: How to Reverse a List in Python

READ:  Python Turtle Screen Size

Method-4 Python Write List to File using the JSON module

In this method, we use the json module to write the list to a file in JSON format. We use the dump() method to write the list to the file in a JSON-encoded format.

# Import the json module, which provides an easy way to encode and decode JSON data
import json

# Define a list containing different types of values
my_list = ["USA", 2, 3, 4, 5]

# Open a file named 'output.json' in write mode using a context manager
# and use the json.dump() function to write the contents of the list to the file in JSON format
with open('output.json', 'w') as f:
    json.dump(my_list, f)

The above code imports the json module, which provides functionality for working with JSON data. It defines a list called my_list containing various data types.

  • It then uses the with statement to open a new file called ‘output.json’ in write mode and writes the contents of the list to the file in JSON format using the json.dump() function.

Read: How to find smallest number in a Python list

Method-5: Python Write List to File using the pickle

In this method, we use the pickle module to write the list to a file in a binary format. We use the dump() method to write the list to the file in a binary-encoded format.

# Import the pickle module, which provides an easy way to serialize and deserialize Python objects
import pickle

# Define a list containing different types of values
my_list = ["USA", 2, 3, 4, 5]

# Open a file named 'output.pkl' in write mode using a context manager and binary mode 'wb'
# and use the pickle.dump() function to write the contents of the list to the file in binary format
with open('output.pkl', 'wb') as f:
    pickle.dump(my_list, f)

The above code imports the pickle module, It defines a list called my_list containing various data types.

  • It then uses the with statement to open a new file called ‘output.pkl’ in write mode with binary mode ‘wb’, and writes the contents of the list to the file in binary format using the pickle.dump() function.
READ:  How to use PyTorch Cat function

You may also like to read the following Python tutorials.

Conclusion

In this tutorial, we learned how to write python list to file using the different methods:

  • Using a for loop and the write() method
  • Using the writelines() method
  • Using the join() and the write() method
  • Using the JSON module
  • Using the pickle