Deleting a line from a Python text file

February 8, 2023

While I was learning how to work with files in Python, I had a question: How can you delete a line from a file that contains a specific word. I wrote the following code:

arr = []
try:
    with open("test.txt") as file:
        arr = file.readlines()
except FileNotFoundError:
    print("File not found!")

word = "five"
try:
    with open("test.txt", "w") as file:
        for row in arr:
            if word not in row:
                file.write(row)
except FileNotFoundError:
    print("File not found!")

But I would like to know if it is possible to do this without writing all the lines in one array, because the file can sometimes be very large and there can be a lack of memory.

>Solution :

You can write as you read instead of storing

Consider the following:

try:
    with open("test.txt") as file:
        with open("new_test.txt", "w") as new_file:
            for row in file:
                if word not in row:
                    new_file.write(row)
except FileNotFoundError:
    print("File not found!")