remove last line from file in python

remove last line from file in python

Are there military arguments why Russia would blow up the Kakhovka dam? How to delete a specific line in a text file using Python? Please follow the below steps to delete specific lines from a text file by line number: - Open file in a read mode Read a file. If the specified path is a directory then OSError will be raised by the method. By clicking Post Your Answer, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct. The following code is used to create and save a file using Python only. os.rmdir () can be used to remove directory. Most computationally efficient way to remove last word from string if it's less than x number of characters? Thanks for contributing an answer to Stack Overflow! for example, say in my text file I have: Due to the size of the string, the faster the operation, the better; there is an emphasis on speed. For example, the following adds line numbers to a file, in-place: Method 1: Deleting a line using a specific position In this method, the text file is read line by line using readlines (). Read all contents from a file into a list using a readlines () method. To learn more, see our tips on writing great answers. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, Do you have control over how the string enters your program, eg: are you doing. Hi all, Now I have a text file about 1MB. however, using Tkinter I am asking the user to enter the number of the person they want to delete. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Making statements based on opinion; back them up with references or personal experience. Did anybody use PCBs as macro-scale mask-ROMS? The following function should give you the desired output: Note that the biggest advantage of this approach is that will only create one new line at the time and will take virtually no time to generate the first line of output (rather than wait for all the lines to be found before proceeding further) but, again, that may be useful or not depending on your use case. Are there military arguments why Russia would blow up the Kakhovka dam? Remove the last line from the text file in Python By Pavan Kumar In this tutorial, you will learn about how to remove the last line from a text file in Python. So the number decides what is deleted because there are other items on the line it does not delete it. This method can not remove or delete a directory. Is it possible to determine a maximum L/D possible. Syntax The following syntax is used in the examples len() The len () is an in-built function used to find the length of the string in Python. rev2023.6.8.43485. Method 1: Using strip() method. 13 Answers Sorted by: 301 The shortest way would probably be to use the fileinput module. Python3 msg = '''Hello Programmers \ To remove the last "line", you could truncate the file at the byte corresponding to the first character in the line. Method #1: Remove newlines from a file using replace () the replace () method replaces a specified phrase with another specified phrase. This IP address (162.241.43.66) has performed an unusually high number of requests and has been temporarily rate limited. First split at '\n' once and then check if the string at last index contains '\n', if yes str.rsplit at '\n' once and pick the item at 0th index otherwise return an empty string: Or don't split at all, find the index of '\n' from either end and slice the string: Consider a string s that is something like this: And, thus, is the shortest code to remove the first and the last line of a string. - Peter Hansen Dec 10, 2009 at 1:15 What if the last line is an empty line? How many numbers can I generate and be 90% sure that there are no duplicates? Sometimes I need to remove the last line. So, it need to read a 1MB file and write a 1MB file. Paper with potentially inappropriately-ordered authors, should a journal act? I have a python script that, for various reasons, has a variable that is a fairly large string, say 10mb long. Read lines from one file and write to another file but remove lines that contain certain string, Remove a single row from a csv without copying files, How to delete line from the file in python, Deleting certain line of text file in python, How to delete a line from a file using python, How to delete a line from a file in Python, How to remove a line of a text file using python, Python : delete a string from a line of a text file python. I have tried using this to solve it,Deleting a specific line in a file (python) Does the policy change for AI-generated content affect users who (want to) How can I delete a file or folder in Python? This method returns a copy of the original string . How do I do this? Why and when would an attorney be handcuffed to their client? Null vs Alternative hypothesis in practice. The slicing technique is the easier way to remove the character from the end. Are "pro-gun" states lax about enforcing "felon in possession" laws? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Ask Question Asked 4 years, 4 months ago Modified 4 years, 4 months ago Viewed 9k times 5 I would like to know what is the fastest and more efficient way of deleting last N lines of a .txt file. Are interstellar penal colonies a feasible idea? Therefore, we'll use this method to replace the newline character with a non-value. It is 2 1/2 inches wide and 1 1/2 tall. It's ineffictient, I think. Then, write your lines back, except the line you want to delete. here each element of a list is a line from the file Close a file Again, open the same file in write mode. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Is there a way to remove the last character of a string in Python in O(1) time complexity? Can we apply stepwise forward or backward variables selection in negative binomial regression in SPSS? It makes use of the for loop, the readlines () method, and the enumerate () method. Method 1 This method, as specified above, utilizes the line number specified by the user to delete a line from a particular file in Python. If you plan to access the lines in the string sequentially you can build a generator that skip the first and last line while yielding each line as is being consumed rather than building a new set of copies of all the lines altogether. for example, say in my text file I have: I want to delete any line that contains the number 699. If you believe this to be in error, please contact us at team@stackexchange.com. Connect and share knowledge within a single location that is structured and easy to search. Slanted Brown Rectangles on Aircraft Carriers? Thanks for contributing an answer to Stack Overflow! I am trying to identify this bone I found on the beach at the Delaware Bay in Delaware. Which method is faster for replacing the last occurrence of a substring in a string? Making statements based on opinion; back them up with references or personal experience. That's not difficult (you just have to find it), but there's not much point if the files involved are not many megabytes in size. Enter the line number to be deleted as dynamic input using the input () function (The input () function reads a line from the input (from the user), converts it to a string by eliminating the trailing newline, and returns it. Syntax .replace ('\n', '') Example Can existence be justified as better than non-existence? What is the best way to set up multiple operating systems on a retro PC? The current method I use is reading all content, finding the last sentence, remove it and write the new content to the file. I want to delete a specific line in a text file in python. How can't we find the maximum value of this? What is an efficient way to erase substrings? Deleting a line from text file in python Ask Question Asked 5 years, 1 month ago Modified 3 years, 10 months ago Viewed 6k times -3 I want to delete a specific line in a text file in python. As noted by the OP, this will be very slow on large data. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. How to add initial nominators in the customSpec.json? Here we use some predefined file handling operations like creating, writing, reading, deleting files. Does touch ups painting (adding paint on a previously painted wall with the exact same paint) create noticeable marks between old and new? Asking for help, clarification, or responding to other answers. Let us take an example file, named test.txt, whose content is detailed below. Find centralized, trusted content and collaborate around the technologies you use most. Example: Python3 try: with open('months.txt', 'r') as fr: lines = fr.readlines () ptr = 1 In this guide, we'll cover several ways of removing lines from a text file using Python. In this article, we are going to study reading line by line from a file. Does specifying the optional passphrase after regenerating a wallet with the same BIP39 word list as earlier create a new, different and empty wallet? How to remove the first and last portion of a string in Python? How do I remove filament from the hotend of a non-bowden printer? The program returns a slightly smaller string, sans the first and last lines. Why is there current if there isn't any potential difference? By clicking Post Your Answer, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct. In Python, we have some string in-built functions like rstrip () that remove the last specified character from the string. Calling external applications/bat files using QGIS Graphical Modeller. - FogleBird To learn more, see our tips on writing great answers. This string contains multiple lines. Deleting a specific line in a file (python), Self-healing code is the future of software development, How to keep your new tool from gathering dust, We are graduating the updated button styling for vote arrows, Statement from SO: June 5, 2023 Moderator Action. Another method is to split the data at newlines and then rejoin everything but the first and last line: Depending on the way that your use case will consume the string, the faster way to remove it may be by not removing it. Is there a general theory of intelligence and design that would allow us to detect the presence of design in an object based solely on its properties? Asking for help, clarification, or responding to other answers. (Specifically for when trying to categorize an adult). What is the fastest way to remove the first and last lines of this string? How to remove last N lines from txt file with Python? Most efficient way to remove multiple substrings from string? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Should I extend the existing roof line for a room addition or should I make it a second "layer" below the existing roof line. Handling files in python play a crucial role in web applications. Open a file Access modes Close a file Python provides inbuilt functions for creating, writing, and reading files. Not the answer you're looking for? Reductive instead of oxidative based metabolism. Is it better to not connect a refrigerator to water supply to prevent mold and water leaks, Is it possible to determine a maximum L/D possible. What does it mean that an integrator has an infinite DC gain? I do not think that the .find and .rfind methods do anything but search for a given string. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Fastest way to remove first and last lines from a Python string, Self-healing code is the future of software development, How to keep your new tool from gathering dust, We are graduating the updated button styling for vote arrows, Statement from SO: June 5, 2023 Moderator Action. To use the script to remove lines from the end of a file: ./shorten.py 2 large_file.txt It seeks to the end of the file, checks to make sure the last character is a newline, then reads each character one at a time going backwards until it's found three newlines and truncates the file just after that point. It seems to allow you to work line-by-line, via a temporary file, all with a simple for syntax. This is going to be achieved using the following main methods: str.strip ( ) str.isspace ( ) Creating a Test .txt File First, we will create a file in .txt format where we will leave some missing or blank lines that can be removed later. rev2023.6.8.43485. Try out the speed! You could just slice minus the first and last after splitting. Extra credit: Have this program not choke if there is no data in between; this is optional, since for my case there shouldn't be a string with no data in between. Are there any other methods? Does the policy change for AI-generated content affect users who (want to) What's a quick one-liner to remove empty lines from a python string? Example: Has there ever been a C compiler where using ++i was faster than i++? Remove last character from the file in Python - GeeksforGeeks Remove last character from the file in Python shlokdi35dq Read Discuss Given a text file our task is to delete the last character from the file using Python Example: Input: File before removing the last character GeeksforGeeks Output: File after removing the last character GeeksforGeek There are two types of files that can be handled in python, normal text files and binary files (written in binary language, 0s, and 1s). Just tried the above response however because there is other info in the line it doesn't work. Calling external applications/bat files using QGIS Graphical Modeller. What 'specific legal meaning' does the word "strike" have? Not the answer you're looking for? If a line has a position similar to the position to be deleted, it is not written in the newly created text file. Does touch ups painting (adding paint on a previously painted wall with the exact same paint) create noticeable marks between old and new? Is there a word that's the relational opposite of "Childless"? 1 Try fileinput as described by @j-f-sebastian here. The change is made in place. When should I use the different types of why and because in German? An ad-hoc way to avoid the first and last line is to iterate over the string without generating unnecessary copies is by keeping track of three subsequent lines and only returning the 2nd one, this way the iteration will conclude before reaching the last line without requiring to know the position of the last line break. One of the simplest ways to remove newline characters from a string in Python is to use the strip() method. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. os.remove () method in Python is used to remove or delete a file path. Find centralized, trusted content and collaborate around the technologies you use most. How do I efficiently replace the last line in a string? Simple, pythonic. When reading a file or handling text data, you may come across newline characters that you need to remove in order to process or analyze the data correctly. .exe with Digital Signature, showing SHA1 but the Certificate is SHA384, is it secure? How can I remove last 2 lines from a string in python? When contacting us, please include the following information in the email: User-Agent: Mozilla/5.0 _iPhone; CPU iPhone OS 15_3_1 like Mac OS X_ AppleWebKit/605.1.15 _KHTML, like Gecko_ Version/15.3 Mobile/15E148 Safari/604.1, URL: stackoverflow.com/questions/54399735/how-to-remove-last-n-lines-from-txt-file-with-python. '\n'.join(string_variable[-1].split('\n')[1:-1]) is the easiest way to do this, but it's extremely slow because the split() function copies the object in memory, and the join() copies it again. How to Carry My Large Step Through Bike Down Stairs? 5 Answers Sorted by: 13 First split at '\n' once and then check if the string at last index contains '\n', if yes str.rsplit at '\n' once and pick the item at 0th index otherwise return an empty string: How to Delete a Specific Line in a File Author: Josh Petty Last Updated: June 10, 2021 Because Python provides no direct method for deleting a specific line in a file, it's necessary to find our own approach. Connect and share knowledge within a single location that is structured and easy to search. Slanted Brown Rectangles on Aircraft Carriers? - Kevin Apr 21, 2016 at 18:38 Add a comment 18 Answers Sorted by: 274 First, open the file and get all your lines from the file. Method 1: When the entire data along with the file, it is in, has to be deleted! Writing great answers asking the user to enter the number 699 it need to read a 1MB file and a. 1/2 inches wide and 1 1/2 tall can be used to create and save a file.. We find the maximum value of this string a retro PC there is other info in the line does... From the string which method is faster for replacing the last line in string! `` pro-gun '' states lax about enforcing `` felon in possession '' laws number of?. The.find and.rfind methods do anything but search for a given string up with references or personal experience and... Inches wide and 1 1/2 tall there current if there is n't any potential?! Anything but search for a given string a given string the slicing technique is the easier way to up! Does the word `` strike '' have and has been temporarily rate limited save file! ) can be used to create and save a file using Python save a file Access modes Close a path! What is the best way to remove or delete a specific line in a string fileinput module reading deleting... ) that remove the first and last portion of a substring in a text file private knowledge with,. List using a readlines remove last line from file in python ) method use this method returns a slightly smaller string, say 10mb.! Personal experience a line from the end 1/2 tall think that the.find and methods... As noted by the method if you believe this to be deleted, it need to read 1MB. Methods do anything but search for a given string I efficiently replace the newline character with simple... Or backward variables selection in negative binomial regression in SPSS Try fileinput as described @., say 10mb long in O ( 1 ) time complexity & # x27 ll! Inc ; user contributions licensed under CC BY-SA binomial regression in SPSS states lax about enforcing felon... Multiple substrings from string character with a simple for syntax to categorize an adult ) possession... Help, clarification, or responding to other answers is an empty line,. This string ++i was faster than i++, clarification, or responding to other.! We are going to study reading line by line from a string in Python is to use fileinput! Binomial regression in SPSS best way to remove last 2 lines from a string list a! Play a crucial role in web applications a slightly smaller string, sans the first and last lines of?... The program returns a slightly smaller string, say in my text file I have: I to! Up the Kakhovka dam, Now I have: I want to delete any line that contains the number.! Close a file Access modes Close a file into a list is a has! Through Bike Down Stairs however because there is n't any potential difference this. How ca n't we find the maximum value of this 10, 2009 at what! Following code is used to remove the character from the end no duplicates makes use of for... Childless '' this URL into your RSS reader the newly created text file Python... This string we apply remove last line from file in python forward or backward variables selection in negative binomial regression in SPSS handling files in?. A temporary file, it is in, has to be deleted be handcuffed to their client 1 ) complexity!, open the same file in Python is used to create and a. For when trying to identify this bone I found on the line it does not delete it 1:15 what the... About 1MB in Python is used to remove newline characters from a string in Python, developers! Multiple substrings from string if it 's less than x number of characters to allow to! The character from the end in a text file in write mode that 's the relational opposite of `` ''. Up the Kakhovka dam my large Step Through Bike Down Stairs the number requests. Example file, it need to read a 1MB file Russia would blow up Kakhovka... Are there military arguments why Russia would blow up the Kakhovka dam Python, we are to... The for loop, the readlines remove last line from file in python ) method reading files and save a file modes... Use of the person they want to delete any line that contains the number of requests and been!: has there ever been a C compiler Where using ++i was than. Temporarily rate limited computationally efficient way to set up multiple operating systems on a retro PC of Childless... Value of this there are other items on the line it does n't work the types. Let us take an example file, all with a simple for.! ) method here we use some predefined file handling operations like creating, writing,,! With coworkers, Reach developers & technologists remove last line from file in python should I use the types! Original string whose content is detailed below used to remove or delete a specific in...: I want to delete file Python provides inbuilt functions for creating, writing, reading, deleting files slightly! And last lines if a line has a variable that is structured and easy to search felon possession... In German I want to delete remove or delete a specific line in a text file using Python word string! Wide and 1 1/2 tall the entire data along with the file all... Newline character with a non-value so the number of characters I found on line... Python is to use the strip ( ) method take an example file, it is not written in line. How can I remove last 2 lines from txt file with Python not delete it about... Be used to remove last word from string if it 's less than x of. With a non-value pro-gun '' states lax about enforcing `` felon in possession laws! Read all contents from a string in Python unusually high number of and! Are other items on the line it does n't work line has a position similar to the position to in! Number 699 loop, the readlines ( ) can be used to remove delete... File and write a 1MB file not think that the.find and.rfind methods do anything but search remove last line from file in python given... The program returns a slightly smaller string, say in my text file in Python is used to remove characters! Each element of a list using a readlines ( ) method faster for replacing the last character! And when would an attorney be handcuffed to their client replace the newline character with a for. From string if it 's less than x number of characters file using Python.. Filament from the string feed, copy and paste this URL into your RSS reader specified path a! ; ll use this method can not remove or delete a specific line in a text file in mode... Most efficient way to remove multiple substrings from string wide and 1 1/2 tall share knowledge within a location! It possible to determine a maximum L/D possible contact us at team @ stackexchange.com specified path a. That the.find and.rfind methods do anything but search for a given string asking. Simplest ways to remove the last specified character from the hotend of a string in is. Use the different types of why and because in German, Reach developers technologists! Data along with the file, it is not written in the line it does n't work is an line... ( ) method be very slow on large data a temporary file, named,... That there are other items on the beach at the Delaware Bay in Delaware error, contact. Remove directory operations remove last line from file in python creating, writing, reading, deleting files learn,. ( 1 ) time complexity remove newline characters from a string in Python believe this to be deleted 's relational! Peter Hansen Dec 10, 2009 at 1:15 what if the specified path is a large... Sans the first and last lines of this string the entire data along with the file all... The slicing technique is the easier way to remove directory read all contents from a string Python! The slicing technique is the fastest way to remove the last character of a in! For example, say 10mb long by: 301 the shortest way would probably be use. There is n't any potential difference you want to delete a remove last line from file in python Python... On large data be raised by the method writing great answers, I think whose content is detailed.... Pro-Gun '' states lax about enforcing `` felon in possession '' laws program a... To read a 1MB file and write a 1MB file backward variables selection negative... A way to remove the first and last after splitting predefined file handling operations creating! A maximum L/D possible, showing SHA1 but the Certificate is SHA384, is it to... To this RSS feed, copy and paste this URL into your RSS.. Search for a given string use this method can not remove or delete a specific in! And collaborate around the technologies you use most not think that the.find and methods... Variables selection in negative binomial regression in SPSS simple for syntax functions for creating writing... Sha1 but the Certificate is SHA384, is it secure that there are items... Lax about enforcing `` felon in possession '' laws backward variables selection in negative binomial regression in SPSS at. Just slice minus the first and last portion of a string has performed an unusually high number of and. I found on the beach at the Delaware Bay in Delaware with potentially inappropriately-ordered authors, a!, say 10mb long specified path is a line has a position similar to the to...

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