Python Program to Find and Remove Duplicate Lines in a Large Text File

In this article, we will be solving a very interesting question of data file handling with python based on text file. According to the question we have to find and remove duplicate lines in a large text file.

If you like the article content, then share it in your coding groups so that more people can take advantage of the content. So, without wasting any time let's solve this question.

Question - Write a Python Program to Find and Remove Duplicate Lines in a Large Text File

Logic and Explanation

Question - Write a Python Program to Find and Remove Duplicate Lines in a Large Text File

Python Program to Find and Remove Duplicate Lines in a Large Text File - We have to find and remove the duplicate lines present in a large text file. Suppose you are given a text file "content.txt". So, first thing we will be doing is to opening the text file in read mode.

with open("content.txt", "r") as f:

After opening the text file in read mode, we will read this file using the python built-in method readlines which will create a list containing lines of the file demo.txt as elements.

Thereafter, we will check for the duplicate elements of the list and will remove those elements i.e. lines which are repeated in the text file.

If you want to understand the logic for removing duplicate elements from a list you can this post - Python Program to Remove Duplicate Elements from List

I hope the logic the flow of the question is clear to you that how we will approach this question. Now you can check the source code of the program for better clarity. In case of any doubt feel free to ask in the comments below.

with open("content.txt", "r") as f:
    linelist = f.readlines()

#Temporary List
R = []
for line in linelist:
    if line not in R:
        R.append(line)    

#Writing Unique Lines in Text File
with open("content.txt", "w") as f:
    for line in R:
        f.write(line)

Now here R is a temporary list created to store the unique lines. We check each line if it is already present in the R then we will not append it in R and if not present in it we will append. Thus at end we get R as a unique list of lines.

Finally we will write this list of unique lines in our text file. In this way, all the duplicate lines are removed from the text file and we get a file with unique lines.

So, I hope you liked the article and you would have found the content of the article useful and helpful for you. Share this article in your coding communities so that more people can take advantage of the content. Also, In case of any doubt feel free to ask in the comments below.

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Enjoy Coding!!!

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