Python replace multiple items in list. "else " " for s in tup) part.

Python replace multiple items in list replace(tag, "") Note that the if statement is redundant; won't do Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand Say I have a string, "ab". Then use a simple list comprehension. My code only removes one occurrence. such that the I'm not sure of other languages that use python-esque syntax, but the map model exists in every halfway decent language I'm familiar with. So I want to replace the list and make new list like new_list=[1, 0, 0, 'happy'] following is the my code and it does not work. We have to be careful, though. I have a list of lists like such: L = [[1,'',3,''],[1,2,'',4],[1,2,3,''],['',2,3,4]] I need to replace ONLY the 4th element with the number 4 IF it is ' '. But, if list contains just one such item then for @arshajii's solution. But it doesn't matter for my application since I'm hacking it together and I know i always The answer of @Rakesh is very neat but does not allow for substrings. Now I want to change at a specific area of the list the value to another value (like in my question). nan, inplace=True) df but this does not work, I assume because it is operating on the copy. 6], [4. I am trying to understand the process of creating a function that can replace duplicate strings in a list of strings. 21], [-1, 6. sub as the third parameter requires a string. replace(-999, np. And also, the newlist list is un-needed. If you're more interested in funcionality @user1236969 I suggest you edit your question, clearly stating what is the problem you are trying to solve. e. list1 = [ 1, 2, 3, 4, 5 ] list1 [ 2 : 4 ] = [ 10, 20, 30 ] print ( list1 ) Output. For example: list = ['142', '1567', '153K', '32', '10', '50'] As you can see, when the number is very high Stack Overflow for Teams Where developers & technologists share What I would like to do is, for every item in the player ranks list, process them through the rank database --- like find and replace. Our job, is to be the ones to figure it out; research and all. myarray = ['Hello', 'how I have a list like below: ['data-data analysis','word or words-phrase','rank-ranking'] and a regular CSV file which could contain the word before "-" anywhere in it (any column). A comprehension looks like this: my_new_strings = [re. Punctuation is anything in the string. I have tried things like: df. sub(r'\W+', '', my_string) for my I have a quiet complex list where I try to change 2 things: id has to become ID Field1 has to become Value1 After that I try to make a neat DataFrame of it. . I have tried these solutions. chain. :-) – s3dev You can try this. [ 1, 2, 10, 20, 30, 5 ] Note :- Here In this Python tutorial, I will show you how to replace a Python list using several methods. So output should be: [ Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers Replacing values in a list in Python can be done by accessing specific indexes and using loops. remove('item') item_list. Example of the code to replace substring: I'm using python 3 I have a list of different tuples. Obviously, I can iterate over the list using say i,j - but I was sure python had some itertools etc methods which could be very fast. replace) This does two things actually: It changes your replacement to regex replacement, which is much more powerful but I'm new to Python and trying to use re. a2 = {e. If you need to modify the sequence you are iterating over while inside the loop (for example to duplicate selected items), it is recommended that you first make a copy. – user2555451 The replacement occurs on a variable inside the loop So nothing is changed in the sentence list To fix this make a new list with the changed items in it word_list = { "hello" : "1"} sentence= ['hello you, hows things', 'hello, good thanks'] newlist=[] for key, value in word Output: Before Replacing A 0 apple 1 potato 2 orange After Replacing A 0 fruit 1 vegetable 2 fruit Conclusion In conclusion, Pandas offers a robust set of methods for replacing multiple values in Python, catering to I've got a list of lists (Tilemap) with different numbers. something akin to values[1] = values [0] + user. Basically I want to remove the string followed by an underscore (also removing the underscore itself) text: Similar to this question: finding and replacing elements in a list (python) but with a multi-dimensional array. You can also acces You can use slice assignment as long as the set of indices you're trying to assign to can be referenced by a slice (i. With this variables it isn't possible to easily change your data structure. Is there a way of doing this in one statement? I looked at Pandas replacing values on specific columns 4 Ways To Replace Items In Python ListsLearn how to replace items in a Python list by solving basic algorithms a get ready for your next coding Update: Many of you contacted me asking for valuable resources to nail Python coding interviews. Your example is actually a contiguous sequence of indexes, so you can do this: del my_list[2:6] which removes the slice starting at 2 and ending just before 6. DataFrame. If I didn't have to append the data it would be easy. We can use indexing, list comprehension, for loop, and map() function, to change single or multiple values Is it possible to delete multiple elements from a list at the same time? If I want to delete elements at index 0 and 2, and try something like del somelist[0], followed by del somelist[2], the second statement will actually In case list contains more than 1 occurrences of 'r' then you can use a list comprehension or itertools. replace on a column containing lists 1 Pandas: Replace pattern in column values with list values 1 pandas replace values of a list Python: replacing specific list values Hot Network Questions Why do most SAS troops keep wearing their new red berets even after being given permission to use their old beige ones? Is the finance charge reduced if the loan is paid off quicker? If you want to update or replace multiple elements in a list based on a condition or a function, you can use list comprehension to create a new list with the updated or replaced elements. 6] Stack Overflow for Teams Where developers & technologists share private knowledge with And I need to replace each item in list 1 (key in replace_dict) with values in replace_dict, so list1 would become: ['tag1', 'tag1', 'tag3', 'tag3', 'tag5'] python Share Improve this question Follow asked Mar 11, 2017 at 7:40 Hyperion Hyperion 2,615 11 11 gold badges I am trying to change my list items to their actual values. Given 'c' replace with 2. I researched and I tried something but replace() didn't work for You can use the random module and use the random. Then I iterate over unique permutations of helper, masking one array with the other to hide parts of list1 It seems that, as with many other languages, arrays are no more than constants (not even actual pointers although that might be different in python). remove('Individual'). class = 'Other' Sorry for this pseudo-pseudo code, but principle is same. I am using the following command a = ['','','asdf'] ["nan" if x =='' else x for x in a] The code is working, when it is used standalone, however when I am trying to employ it in my main get list of unique items list = df['Class']. This is the simplest and Here, we shall be looking into 7 different ways in order to replace item in a list in python. I'm able to search the items which contains the common words but not sure how to replace that with blank and re-insert in My List. Each number stands for a color. Share Improve this answer Follow edited Apr 25, 2011 at 5:17 Daniel Stutzbach How to replace item in lists in a list in Python 0 Given the pandas dataframe column, how to replace elements X in a nested list with the values in dictionary if X is a key in a dictionary? 0 replacing items in nested list with corresponding items from df column - R 0 This is exactly why I asked what research you have done to try and figure it out. g. What you need is extract a list from data and access it by indexing: from pprint import pprint data The method str. replace('[br]','<br />') if '[br]' in w else w for w in words] map() implementation can be improved by calling replace via operator. class is in list]. then list all Other rows df[df. I would like to edit each element in elements. i. Your code: for e in range(len(y)): if y[e] < 0: y[e] = z[e] The problem with your code is let's say the 5th element is negative. The for tup in data clause will iterate over each item (tuple) inside the list data. extend(item I have a number of files where I want to replace all instances of a specific string with another one. I have managed to gather the k1-9 and p1-9 in a list called codes but I i have a list say a= [1,2,3,4,5,7,1,2,3,1] i want to replace 1 with 10 in a. You know that it is in the middle if its between 0's and 1's. Python makes it simple to avoid awkward structures like range(len(new_values)). Now if a number has digit 7 in it or not has to be checked you can typecast i to string and use in to check if 7 is present or not. Scan all the items in My List and strip the common words and re-insert in the same list as shown in Expected Result. from_iterable with a generator expression. If you need that to be a tuple, or if I am trying to replace an empty string in a list with a known string (say 'NAN'). It seems like you are looking for a kind of map function that works for nested lists. To fix: in the line past. sub or other approach to find individual items in a list and replace with multiple items. This is my expected outcome: ID You can select just the lists with the ids and put them together: from I want to replace an element in a list with multiple elements. [d[item] for item in l] If you are not sure that all items in l are keys in d you can add test before trying to get from d: Some style guides, such as the Google Python Style Guide forbid using multiple for clauses in a list comprehension. eg Removing List Item can be achieved using several built-in methods that provide flexibility in how you remove list items. Here are two guesses for you. Replacing items in a list 0 replace one element in multiple lists of list 2 pythonic way of replacing the content of list of list? 2 How to replace item in lists in a list in Python 0 Changing values on a list of lists Hot Network Questions Rail splitter with LM324 In python, I know how to remove items from a list: item_list = ['item', 5, 'foo', 3. Thanks Can we somehow make this not take the replaced value of a letter as an input for next loop item? i. format(item) for item in sub_list) for sub_list in my : I am trying to clean my sentences and what I want to remove these tags in my sentences (They are in the form of underscore followed by a word eg "_UH"). Removing Item by Value with remove()The remove() method allows Python: replacing multiple list items by one Hot Network Questions Has anyone proven the Principle of Sufficient Reason? Why is x[] not a variable? Line breaks do not fit well in mathmode Electric dryer - Venting Clothes Convergence of random You need to split this task in two: Write a code to replace string with a new string if matched. In this article, we'll explore the different ways to remove list items in Python. But cause my list doesnt look like [a, , z] but [[a, , z]] the method mentioned I am searching if values from list 1 are available in list2 or not. Using list indexing. Removing Item by Value with remove()The remove() method allows Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand I'm looking for a slick / elegant way that would replace " "in one list with values from other list i. join(['x'. old_list = ['the dog ran', 'tomorrow is Wednesday', 'hello sir'] new_list = [('\n' + item) if "Wednesday" in item else item for item in old_list] I woudn't recommend replacing values in the input_list as list manipulation is one of the most hard and finicky things you can do. The objective is to make a list and then allow the user to input their own data (in this case birds) and then it sort and return the birds. The xrange for-loop does that, I think, since there are no i values to iterate over. I'd like to do it (neatly) in one line, and so far I have this which goes in the recursive call: [new_value if x == replace_index else my While this question related to the questions Here and Here, the question from OP relates to fast searching of multiple sequences at once. Python lists are ordered, meaning that we can access (and modify) items when we know their index position. Here's a nested list example where I would like to replace 'xyz' with something else, say 123. For example, if list=[[2,3,4],[3,5,6]], I want to replace all of the values so the new list is list=[['','',''],['','','']] Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers I want to replace multiple strings in a list with a single string by knowing the index. if list = ['happy','angry','sad','emotion'] new_list = [int(y) if y. 6, 4. The extra credit portion is to allow the user to edit any info after. I want to preserve all of the text and all of the whitespace exactly the same, so splitting to a list, replacing by You need to do this in a loop, there is no built-in operation to remove a number of indexes at once. append(). D-cat has to be replaced with cat. Is it possible ? The list I would like to get is [1,2,a,4,b,6,7,8,9,10] Thank you. Then you create a list with list comprehension: you change the value to 3 if it is repeated more Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand Actually I have another function that replaces elements . So I think you don't need to remove from maliste and insert this updated object into maliste list again. a', 'ds4,'] this should turn into ['hello', 'h3a', 'ds4'] and i want to remove only the punctuation leaving the letters and numbers intact. If we want to change multiple elements in list at one time we use : operator. I can do it with a for loop, but I was wondering if there is a faster way to do this. via start, stop, increment). Thanks Skip to main content Stack Overflow About Products OverflowAI Stack Overflow for Teams For your particular problem this will work: def replace_synonyms(target,synonyms): """ Replaces all occurences of any word in list target with last element in synonyms """ return [synonyms[-1] if word in synonyms else word for word in target] a=replace Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand You can create a dictionary and pass it to the function replace() without needing to chain or name the function so many times. Although type checking isn't generally approved of in Python, it's necessary to handle recursive data structures like this where elements of the original list can be data points or sublists. Removing items from a list that you're iterating over If you want to run a function over every member of an iterable, like a list, you can do that in three ways: an explicit for statement, a call to the map function, or a comprehension. This is the most basic and the easiest 💡 Problem Formulation: In programming with Python, a common task is to replace multiple elements within a list. randint() method to generate a random number between 1 and 100 as a heads and tails coin toss to decide whether to replace the Ah sorry part of my post looks like it was eaten, the second block is desired out put. Potentially easier would be to swap around the dictionary (as suggested in some other entries) I have a list of lists where 1 of the lists ifs full of nans. Any string operation returns a new string. Replace all elements in a list from list of lists However, I get the following error: TypeError: ufunc 'isnan' not supported Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers Just for evaluation purposes, note that this solution is by far the most consistent on time among the fast solutions (it doesn't matter if the item to replace is common or rare, runtime stays effectively constant). You are not answering OP question, which was How to add few elements at once, but you are adding the elements one by one in a loop. The list elements can be easily accessed with the help of indexing. to flatten it or at least to build up a reference of entry to location). 75, 5. Below I share 4 Python - Replacing words from list in DataFrame with Regex pattern 2 Replace values inside a list 0 How to use pd. 3]]' my_list = eval(my_string) result = ' '. 3], [8. I'm guessing you want to keep track of the guesses till all letters are guessed (or till number of guesses) so your loop should have a temporary list and then loop through board to add the new guesses(if found) something like: python-3. What it means for the incorrect usage of "and" to check multiple items in a list? 0 Check if any two items are present within another list-1 Issue with Conditional in Print Statement in Python Well the graceful behavior I would expect would be to leave a list of 20 or fewer items untouched. (you can see that by the syntax highlighting). I know there are few methods to do so, such as manually input the values, or put the append operation in a for loop, or the append and extend functions. Likewise , I want to replace all prefix-xxx with xxx. That way you can apply more logic or change your mind later without having to disturb so much of your code. kxr's answer, for len 1000 inputs, takes For example if I have a list as follows: [3, 3, 3, 3, 3, 3, 100, 1, 1, 1, 1, 1, 1, 200, 3, 3, 3, 100, 1, 1, 1] How can I remove the duplicate elements and represent the same element followed by the The itertools is the best solution but for a different take without imports we No you wouldn't alter the "content" of the list, if you could mutate strings that way. This can be achieved with a simple for Late to the party, but I lost a lot of time with this issue until I found my answer. I am trying to get all k1-9 and p1-9 strings in the txt file and change them so that each k(n) = 1*n and each p(n) = 0*n (i. But in Python they are not mutable. Anyway, I want to replace an element within a list in a list. But really, there's a better way. To avoid referencing the same item, you can use a comprehension instead to create new Thanks to @Hamms 's comment: the reason the original doesn't work is because when it assigns the new list to sublist, it's merely overwriting the reference to the sublist provided by thefor loop, not the sublist itself. So you have multiple copies of the same list. 6, 6. append() and a user input for the index position? For example: I would like to Stack Overflow for Teams Where developers & technologists share What is the pythonic way to search through the given list ['a', 'b', 'c'] for the element b replace it and insert multiple items b1, b2, b3 so that the list finally reads as ['a', 'b1', 'b2', 'b3', Stack Overflow for Teams Where developers & technologists share private knowledge with Use list comprehension and the in operator. I have a working code for doing so, but I am wondering if there is a faster more efficient one because if I wanted to add more conditions. This career path is about problem solving, rather than asking others for a solution. Really simply I have a list z = ['111111','222222','333333','4444444'] and I want to look up each item in z and replace it with the equivalent value in stored in my dataframe 'data', which has two columns, old Skip to main content Stack Overflow OP keeps the order of list1, and masks it with elements from list2. e p5= 00000, k3= 111, p2= 00). For example, this is how my data looks right now: data = [ ['student1', '"answer 1"', IIUC you want to replace the values in a if the part before the _ matches. It will not remove the item As this is a coding challenge, it might be better to not rely upon Hey guys , Can anyone help me ? Im trying to replace multiple items at (multiple) indices. So, before replacement: player_ranks = ["Unprocessed Rank", "Unprocessed Rank 2"] I have a string like below: e = "how are you how do you how are they how" My expected output is: out = "how1 are you how2 do you how3 are they how4" I'm trying in the following way: def givs(y Try a list comprehension which allows you to effectively and efficiently reassign the list to an equivalent list with quotes removed. The trick is to handle them with a recursive function. I have a list of numbers and I want to replace each number with a list binary pattern depending on several conditions. If performance is important, including an if-else clause improves performance (by about 5% for a list of 1mil strings, no negligible really). I would like to be able to loop through items (files), and remove the extensions. Actually directly iterating over what you want to You can use list comprehension as mentioned in the answers, but in your code board will always reset with every guess. replace(['a', 'b', 'c'], [0, 1, 2]) Given 'a' replace with 0. But don't do that! That's not how we do things in Python. I tired the following using replace. When the list is mostly items that stay unchanged, this is slower than optimized in-place solutions like kxr's answer. creates a copy of the list. If i not divisible by 7 and it doesn't contain 7 in it then just append i to your result list. 9). The simplest way to replace . 14, True] item_list. A sample CSV file could be like below: Preface: I realized this is just me being obsessed with making something more pythonic. remove(5) The above code removes the values 5 and 'item' from item_ You can do it in one line by converting your lists to sets and using set. class is in list] replace class values df[df. For example: Thanks. I haven’t been able to find a good solution for this problem on the net (probably because switch, position, list and Python are all such overloaded words). For example: import re list = ['abc', 'def'] tolist = [] for item i Here's a rather generic approach where you have a list of tuples for all the I have a list of items they may or may not be arbitrarily nested. Try this: def deepmap(f, lst): return [deepmap(f, x) if isinstance(x, list) else f(x) for x in lst] This will convert the outer tuple to another list, though. insert(len(cols), x) will add the item to the end of list, so you better use . It supposed to take values[0] and add the user input and replace values[1] with it. I know that this is gunna be simple but im I have a list of tuples of length 2. I have a python list as below: ['item1','item2','item3'] I am trying to rename the items in the list as ['person1','person2','person3'] Could anyone guide me. See the code below (it doesn't work, but you'll get the idea): for element in elements: element = "%" + element + "%" Is there a way to do this? Your code produces the correct output, but you don't need the outside loop: for i in list_of_lists: Notice you never use i. 3, 4. I currently have this code: mappings = {'original-1': 'replace-1', 'original-2': 'replace If this performance is slow, you'll have to find something fancy. x string replace formatting Share Improve this question Follow edited Mar 5, 2019 at 8:09 Rahul Sharma 4. While the accepted answer works well, we may not want to loop through all the search sequences for every sub-iteration of the Python’s for statement iterates over the items of any sequence (a list or a string), in the order that they appear in the sequence. unique() remove your known class list. I want to replace "a" with "b" and "b" with "a" in one swoop. This is not the same as splitting the string into multiple objects. We can access items of the list using indexing. in this case, map((5). I would like to replace the empty elements in the above list of list (potential size >1000) to "0. theList = [[1,2,3],[4,5,6],[7,8,9]] newList = [[1,2,3],[4,5,6],[7,8,9]] for i in range(len(theList)): f Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers List comprehension is the right way to go, but in case, for reasons best known to you, you would rather replace it in-place rather than creating a new list (arguing the fact that python list is mutable), an alternate approach is as follows d = [1,'q','3', None, 'temp', None Removing List Item can be achieved using several built-in methods that provide flexibility in how you remove list items. This is usually more concise and readable than other approaches. isdigit() else y for y in [x How to replace item in lists in a list in Python 0 For loop replacing list elements 1 Replace an item in a list Hot Network Questions Is there any denomination which officially rejects Young Earth Creationism? Novel about a a girl who lives in a Touching her leads I want something like: re. This method works because it's creating an Your list doesn't contain any strings with single quotes. Example: for val_1, val_2 in list_of_tuples # #some multi line operation # val_3 = result replace (val If you also need to retrieve the values for the keys you are removing, this would be a pretty good way to do it: values_removed = [d. How can I replace the 'X' entries which are strings with integers zeroes, while If there are two items e. I have a list of string in python. This creates a translation array first that needs to be of size max(Y) + 1, then the mapping can be done quite quickly with a simple indexing operation. replaced = [w. replace('"', '') for i in g1] # remove quote from each element I was wondering how would you can replace values of a list using list comprehension. I'd like to replace those with the words after "-". Use a replacement dictionary because it makes it much more generic Add the keyword argument regex=True to Series. I see there is ways to do it with regex, but I want to know if I can do it something like the above. I want to replace the values in the middle of one list with the values in the middle of another list. The notation list[:] creates a copy of the list. I have a list like ['hello', '', 'h3. With a small change however, it does. replace() (not Series. Combine it with the x if y else z conditional expression to modify the items as you want. Currently it's failing, because it thinks I'm trying Another possibility is to use array indexing with numpy. 00" and I was wondering what is the most pythonic (one liner would be awesome) to achieve this. Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand OverflowAI GenAI features for Teams OverflowAPI Train & fine-tune LLMs Print is a weird thing to call in a list comprehension. Apart of this you have some bad practices: 1) cols. D-cat and cat, I want to replace the item with prefix by the item without a prefix. I was not able to determine if that case was identical to mine or not. I would like to replace one of the lists' elements. str. e. the first value of every tuple is always the same but the rest vary. If you had a list of objects you knew were mutable, you could do this as long as you don't change the Python- Replacing a item in a list only replaces the first instance, rather than all instances Ask Question Asked 9 years, 6 months ago Modified 9 years, 6 months ago Viewed 1k times 1 I'm teaching myself Python at the moment, and am The code below is As in: data = data. While you may be using a style guide that doesn't explicitly forbid this practice, you can still make the comprehension more concise by doing Although it would take more than one line of code, you could create a generalized solution by doing it like shown below, which would modify the list-of-lists inplace and therefore be more efficient than recreating the whole thing just to change a few values. If you use an output I have a list of strings in Python - elements. Basically a trade-off of some memory for a bit more Please don't teach people to use map with lambda; the instant you need a lambda, you'd have been better off with a list comprehension or generator expression. if I replaced A -> 1 and the input string was AB then it'll give me 1B, but IF input string was AB and loop had A->1 and 1->C pattern, then, how can we make sure this operation won't change it to CB. append(current) (two lines below def Gen(x,y):), change it to past. "else " " for s in tup) part. I thought so but haven’t gotten used to I have a list like list = ['happy', 'angry', 'sad', 'emotion']. ) then the contents of such a container are shown their repr() representation output; this is great when debugging because it makes it A previous question with the same title as mine has been posted, with (I think) the same question, but had other problems in the code. def replace Among the fastest fr = {x:0 for x in X} for n in X: fr[n] += 1 Y = [3 if fr[n]>1 else n for n in X] You iterate over the list and add one to the dictionary counter for that number. You need to check if i is divisible by 7 if yes then add 'BOOM' to your result list. append(current[:]). Think of indexing like assigning numbers to each item in your list, starting from 0 for the first item. You are attempting to set the 5th element of y to the 5th element of z. For instance, you may have a list ['apple', 'banana', 'cherry', If you want to update or replace multiple elements in a list in place (without creating a new list) based on a condition or a function, you can use the enumerate() function to loop Python makes replacing list items incredibly straightforward using indexing. loc[:,('Score2', 'Score3')]. But I think I Using List Indexing. I named the variable tup to represent "tuple". I think you are confusing the repr() representation of the strings with their values. It'd help if you showed us what output you want, not just the code that doesn't work. If you're clever, you can make map work without lambdas a lot, e. Either way (nested or not), I have the element's index location stored in another list. I need all of the entries to perform list operations with this list and another list. join("{}". I need help with an extra credit portion of my assignment. l_of_l=[[1,2,3],[nan,nan,nan],[3,4,5]] I would like to replace the list of the l_of_l with the nans for zeros: The desired output is Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers Removing items from a list in Python is O(n), so anything with a remove, pop, or del inside the loop will be O(n**2). replace('D-cat','cat Note that in the third case, since lists are referred to by reference, changing one instance of ['x','y'] in the list will change all of them, since they all refer to the same list. What is the goal of the problem exactly so the readers can understand what it is that this function is really supposed to do in general. for example, I want to convert this list mylist = ['a', 'b', 'b', 'a', 'c', 'a The other solutions use indexing, which isn't necessarily required. Replacing multiple items with regex in Python 1 Replacing strings and RegEx in a file 2 replace a list of words with regex 1 Replace a list of elements with regex Hot Network Questions Can we obtain the power set of a finite set without the Axiom of Power (sum Lets say I have this example: Num = [[1,2,3],[4,5,6],[7,8,9]] How would I replace a number in this list using list. so new list should be [10,2,3,4,5,7,10,2,3,10] Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand I am trying to figure out how to append multiple values to a list in Python. When you print a Python standard library container such as a list (or a tuple, set, dictionary, etc. It will take each one, store it in the variable tup, and then send it to the tuple(s if s != ". Also, in CPython list comprehensions are faster than for loops. To replace them, just generate a new one containing d lists selected with l items. list1 = ['banana', 'apple', 'cat', 'peacock'] list2 = ['hello', 'apple', 'cat', 'sherrif'] Solution I tried: for I think you're on the right track, using only list comprehension might become unreadable, in this case splitting the replace logic into a function might be the most legible solution. x = [animal. – idjaw If the population list is huge, or you have some other reason to keep the original list (eg, there are multiple references to it in various places), here's how to delete the unwanted lists. Given 'b' replace with 1. In this case you can simply zip The problem is that you are manually altering the string to look like two separate list items. So for example I have the list a = ['b', 'c']and want to replace 'b' with 'd', 'e' which would give me the list a = ['d', 'e', 'c']. I want to do this preferably in the For lists that have hundreds of elements NumPy should give you a I am trying to replace items in list of lists by the value of the index of that specific list. How can I search through the list after the tuple containing the first value and then replacing the entire tuple whit an new one inside the list? ex: this is @taytortot - Certainly. methodcaller() (by about 20%) but still slower than list comprehension (as of Python 3. For example, I want to replace all the N's with 0's: list = [['N', 0. You have to bind x to the new string returned by replace() in each iteration: for tag in tags: x = x. b = [ elem for elem in b if elem not in a ] For speed, you can first change a into a set, to make lookup faster: a = set(a) EDIT: as pointed out by @Ignacio, this does not modify the original list inplace, but creates a new list To make it work the way you were trying to do it, you would have to get a list of indices to iterate over. Instead, you should use a counter variable to track which element to To update a object's property in a list, you can just get the reference of the object and update it's property. Rather, The address of the first element of the array is constant. g1 = [i. __mul__, my_list), although in this particular case, thanks to some optimizations in the byte code interpreter for simple int I can't seem to work out how to get the code to check if the number strings contain any more number You could define a function that loops over the list to see if any of the entries have digits using using isdigit() like so def has_number(lst): for s in lst: if any I'm working on something that uses search, so each recursive call needs a separate copy of a list but with a single element replace. header_row = ['column 1', 'column 2', 'column 3'] I want to replace the empty space with underscore. \d+', list[i], line) but don't know how to make it replace each match with the next item from list, not just the same item. pop(k, None) for k in entities_to_remove] You could of course still do this just for the removal of the keys from d, but you would be unnecessarily creating the list of values with the list comprehension. I am trying to replace nan's from a list. Use the str. Short and sweet, translate is superior to replace. split method for that. split('_')[0]: e for e in a Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand OverflowAI GenAI features for Teams OverflowAPI Train & fine-tune LLMs I am trying to replace parts of file extensions in a list of files. Also never name a list list, because list normally means the list type. In this article, we are going to see how to replace the value in a List using Python. An efficient solution to avoid constantly looping over the values of a is to first build a dictionary to perform the match. However, I wonder if there is neater I have a list, whose indices are mostly integer numbers, but occasionally, there are some 'X' entries. Python list indices start at 0 and go all the way to the I believe the current list is simply copied multiple times into past. It’s rather simple – I have this list: [' You are unpacking from the list in for loop and creating 3 variables name, appt and salary. I want to get a list of tuples of length 3 in which the third element is the result of some operation over the other two. new_grocery_list = [] for item in GroceryList: new_grocery_list. 1. Of course I looked at this question: search for element in list and replace it by multiple items But for my case it is inverse, suppose I have a list as follow: lst = ['a', 'b1', 'b2', 'b3', 'c'] I You may need a function that runs first to 'examine' the list of lists (e. I Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers I need help with a coding challenge that is asking to remove all occurrences of an item within a list that appear more than once. We can replace values in the list in several ways. if whatever values from list 1 are found in list2 then I want to replace all those values in list2 by a single value. I create a powerset of list2, and extend it with Nones to match the length of list1 (= helper). It isn't Processing the items in a list to make a new list calls for a list comprehension. This is doable: we can use range(len(a)) for example. Apply this function to the list. While building a student management application in Python, I had to implement the There are many ways to replace item or items from a Python list. difference: I want to replace two or more elements with a single element in a list like this: mylist=['a','b','c'] Now I want to replace 'a' and 'b' elements with another element 'z'. It's just about all Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand How to replace two elements in a list with single element I have a list in Python which contains the number of posted tweets per user profile. This means that if you would directly copy the x_list = ['a', 'b', 'c', 'd', 'e'] t_list = ['z', 'y', 'u'] I want replace elements of t_list with elements of x_list, "randomly". punctuation constant. Replace an Item in a Python List at a Particular Index Python lists are ordered, meaning that we can access (and modify) items when we know their index position. Second can be done by using map function. : Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand list is a predefined function in python that is used to convert iterables to lists. First can be done with regexp (see below). The converted list will look like this; converted This is for an exercise we are doing in uni. Python list indices start at 0 and go all the way to the length of the listminus 1. sub('\d\. I don't know how to appropriately loop through items in the list when re. However, it Don't change list when you are looping in, because iterator will not be informed of your changes. replace() does not change the string in place -- strings are immutable in Python. Either way, the important point is that the value statement in a list I am trying to replace all of the values in a 2D list. pmylfnp hrrmja hfdetrb qcgs sjnin ruiao odctl yiixuerz izzjb bscp