How do I clone a list so that it doesn't change unexpectedly after assignment? (Actually, I abbreviate it mentally as "-9, on"), But the colon is what tells Python you're giving it a slice and not a regular index. The list is something like this. Method-1: Remove the last element using the pop () method from the Python list. (since creating a list would just be wasteful). They are: Using the Set Data Structure Using List Comprehension Using the dict.fromkeys () method Using Pandas Library Method-1: Removing duplicates from a Python list using set () Learn more about how to do this in my tutorial here (requires Python 3.8+). Yours wouldn't work for that original, either, like you said it's even somewhat impossible. Since the OP's question is about stripping the newline character from the last element, I would reset it with the_list[-1].rstrip(): This works to take out the \n (new line) off a item in a list If the method you choose is more complex, you should turn it into a method: A naive approach would be to rebuild the list with each element processed. A = [ [(a,'rr'),(c,'rr'),(d,'rr'),(b,'zz')], [(g,'rr'),(h,'rr'),(e,'rr'),(b,'zz . Replace the last element in a list with another list. Similar to the approach above, youll use negative indexing to access the last number of items. Let's get started! By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. What are the pitfalls of indirect implicit casting? Cold water swimming - go in quickly? Can a simply connected manifold satisfy ? Either way (nested or not), I have the element's index location stored in another list. How do I split a list into equally-sized chunks? or slowly? How can kaiju exist in nature and not significantly alter civilization? Using robocopy on windows led to infinite subfolder duplication via a stray shortcut file. How can I avoid this? Otherwise just use the slightly I missed that point. The elements in the file were tab- separated so I used split("\t") to separate the elements. @TigerhawkT3 Downvoting an answer just because the question isn't ideal is poor form. lstrip() and rstrip() are left strip and right strip functions resp. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. rev2023.7.24.43543. The strip function removes the whitespace/custom characters on both ends of the string. That is not so bad. Some of our partners may process your data as a part of their legitimate business interest without asking for consent. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Manage Settings To learn more, see our tips on writing great answers. To learn more, see our tips on writing great answers. This failure to account for text files ending in non-newline characters has plagued many UNIX utilities and scripting languages for many years. 593), Stack Overflow at WeAreDevelopers World Congress in Berlin, Temporary policy: Generative AI (e.g., ChatGPT) is banned. list slicing performs n number of operations.Auxiliary Space: O(n), extra space is required where n is the number of elements in the list. How to remove \n from a list element? What is the audible level for digital audio dB units? This does the same as the other answer, just walks the path in a functional fashion: reduce (getitem, loc [:-1], nested) [loc [-1]] = replace. acknowledge that you have read and understood our. What should I do after I found a coding mistake in my masters thesis? This article is being improved by another user right now. 592), How the Python team is adapting the language for an AI future (Ep. Can a Rogue Inquisitive use their passive Insight with Insightful Fighting? This can be helpful for many different items, such as game development and more. That doesn't address the "replace the last element" aspect. What is the smallest audience for a communication that has been deemed capable of defamation? How does Genesis 22:17 "the stars of heavens"tie to Rev. if you just have lists that has tuple or single element, we can first detect if a list has tuples and apply lambda function to replace elements as desired. As you can see the list-comprehension is more effective than map (even that without a lambda). You aren't very specific about what constitutes 'unwanted spaces' but with the simple assumption that it means two spaces in a row a simple approach would be .replace(' ', ' ') to remove doubled spaces. What is the audible level for digital audio dB units? https://docs.python.org/2/tutorial/datastructures.html, What its like to be on the Python Steering Council (Ep. Cold water swimming - go in quickly? In this section, youll learn how to use the reversed() and next() functions to get the last item of a list. Is there a simple way to remove multiple spaces in a string? That's why the idiomatic way of copying lists in Python 2 is, (Lists get list.copy and list.clear in Python 3.). For example using a list generator: With a really large list this can be really inefficient. The elements in a list can have any data type, and they can be mixed. Connect and share knowledge within a single location that is structured and easy to search. Let's see how we can use slicing to remove the last element: items = ["apple", "banana", "orange"] print(items[:-1]) # ['apple', 'banana'] Instead you can use a combination of split and join to remove all excess whitespace. Is there a Python idiom for the last n elements of a sequence? Theyre like the secret sauce that adds flavor and complexity to our neural networks. You can use lstrip() or rstrip() to remove just the left or right side. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing, What are you inputting? Why do capacitors have less energy density than batteries? (Bathroom Shower Ceiling). Get last N elements from given list in Python - Given a Python list we want to find out only e e the last few elements.With slicingThe number of positions to be extracted is given. So for example if loc is [2, 4, 1, 3] then you get getitem(getitem(getitem(nested, 2), 4), 1). Replace an Element in Python List | Delft Stack To replace parts of a python list, you can use slice assignment: >>> array1 = ['A', 'B', 'C', 'D', 'E', 'F'] >>> array2 = ['G', 'H', 'I'] >>> array1 [-1:] = array2 >>> array1 ['A', 'B', 'C', 'D', 'E', 'G', 'H', 'I'] You can use slice assignment to replace any part of a list, including insertion of lists where you do not replace existing elements: Method #1 : Using list slicing This problem can be performed in 1 line rather than using a loop using the list slicing functionality provided by Python. Take back the vote if you believe this is the better way, I think this seems much more pythonic. python - Remove the last N elements of a list - Stack Overflow Let's summarize each method: List indexing: We use the index number of a list item to modify the value associated with that item. Difference in meaning between "the last 7 days" and the preceding 7 days in the following sentence in the figure", Looking for story about robots replacing actors, Anthology TV series, episodes include people forced to dance, waking up from a virtual reality and an acidic rain. Because of this, we can access list items by their index positions. Python: Removing a last element from list of list? Should I trigger a chargeback? Method-1: Deleting an element using the remove () in a Python list The remove () method in Python list, removes the specified element using the element name. But again --- ONLY IN PYTHON3. Thanks :-). The lines has got all the contents of your file. Getting the last item in a Python list using negative indexing is very easy. assuming you're using Python 2.6 or later. In the section above, you learned how to use Python to get the last item from a list. Lets say we wanted to return the last 2 items, we could write the following code: Similar to the example above, we could have have written our index to be [-2:-1]. How to remove the first and last item in a list? You can unsubscribe anytime. How to Replace Values in a List in Python? - GeeksforGeeks You could use the following list comprehension: If you want to avoid importing numpy, though the data suggests that you should be using it, you could actually do the same with: This works as by definition NaNs are never equal to themselves. Python: How to remove \n from a list element 2D? How can I remove a key from a Python dictionary? One could still save some space by assigning to the original list with. @AntoinePinsard Your points are valid. For example I have two arrays a array1 and array2. Lets take a look at how we can make this happen in practise: You can see here that when we print out the list following applying the .pop() method, that the last item has been removed. Can a Rogue Inquisitive use their passive Insight with Insightful Fighting? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Python: Replace the last element in a list with another list I would like to replace one of the lists' elements. Can somebody be charged for having another person physically assault someone for them? If it adds something, make clear what that is. If you would like to change your settings or withdraw consent at any time, the link to do so is in our privacy policy accessible from our home page.. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Is not listing papers published in predatory journals considered dishonest? Accessing elements in a list has many types and variations. I would like to replace the list of the l_of_l with the nans for zeros: for list1 in l_of_l: if all (np.isnan (list1)) == True: list1 = [0] * len (list1) However i am not sure on how could I assign the result again to the l_of_l . Which is the same as nested[2][4][1]. It is nearly 60% faster. Asking for help, clarification, or responding to other answers. Is this mold/mildew? Whichever method you use to clean up a single string, you still need to apply it to each element in the list. For example: "Tigers (plural) are a wild animal (singular)", Line integral on implicit region that can't easily be transformed to parametric region. How to remove "\n" in a list of lists (python), how to remove "\n" from a list of strings, stripping \n from every element of a list. They are: Direct Assignment using Indexing Using List Comprehension Using list slicing For loop While loop Using map () function We will see them one by one using illustrative examples. However, you can't just assign some integers separated by colons to a variable. Python: How do I replace value in a nested list? Thanks for contributing an answer to Stack Overflow! We could argue that "text" files without the ultimate newline are "corrupt" or non-standard; and that may be valid for some programming specifications. Python | Create two lists with first half and second half elements of a Python Program to get Maximum product of elements of list in a 2D list, Python program to interchange first and last elements in a list, Python | Merge first and last elements separately in a list, Python - Find the distance between first and last even elements in a List, Python | Get last element of each sublist, Pandas AI: The Generative AI Python Library, Python for Kids - Fun Tutorial to Learn Python Programming, A-143, 9th Floor, Sovereign Corporate Tower, Sector-136, Noida, Uttar Pradesh - 201305, We use cookies to ensure you have the best browsing experience on our website. What is the smallest audience for a communication that has been deemed capable of defamation? str [:-n]. Write a Python program to replace the last element in a list with What are iterator, iterable, and iteration? Downvote the question not the answer. For example: "Tigers (plural) are a wild animal (singular)". Conclusions from title-drafting and question-content assistance experiments How to remove the last element in each list in a list, List method to delete last element in list as well as all elements. [9, 10, 11, 12] I hope it can help you. Conclusions from title-drafting and question-content assistance experiments Python - How to extract the last x elements from a list, Print the last three items of a list in Python. How does Genesis 22:17 "the stars of heavens"tie to Rev. What's the DC of a Devourer's "trap essence" attack? Here is an unnested example where I would like to do the same substitution: If loc only has one element then you can simply do: Is there something flexible enough to handle both cases? You need to use the slice object: The second argument, None, is required, so that the first argument is interpreted as the start argument otherwise it would be the stop argument. Chain the two together and you end up with: This is both simple and fast. or slowly? Airline refuses to issue proper receipt. Making statements based on opinion; back them up with references or personal experience. When chaining arrays, it may be useful using itertools: Doc: http://docs.python.org/2/library/itertools.html#itertools.chain. If Phileas Fogg had a clock that showed the exact date and time, why didn't he realize that he had arrived a day early? 6:13 when the stars fell to earth? Is not listing papers published in predatory journals considered dishonest? I can get the first 9 like this: num_list [0:9] python list slice Share Improve this question Follow Not the answer you're looking for? ok so given loc = [0,1] you would want to preform the operation: or if we had overly complicated data and loc = [0,1,2,3,4,5,6,7] you would want: In any case we first need to look up each layer before the last element which we can do in a for loop like this: This also works when there is only one item in loc since in that case the for loop is iterating over an empty sequence so there is no need to treat that case seperately.