This is often called a Python 3 feature, but according to PEP 238, it was introduced all the way back in Python 2.2. . python - Taking the first few items of a list until a target sum is How to avoid conflict of interest when dating another employee in a matrix management company? Connect and share knowledge within a single location that is structured and easy to search. 592), Stack Overflow at WeAreDevelopers World Congress in Berlin, Temporary policy: Generative AI (e.g., ChatGPT) is banned. Does Python have private variables in classes? Below is the input list and the desired output. What should I do after I found a coding mistake in my masters thesis? Does this definition of an epimorphism work? Python List Length - Initial Commit In Python, you can create such a repeat list easily using many approaches. Method 1: Using For loop We can iterate over a list in Python by using a simple For loop. Python How to repeat a list's elements in another list content until python - How to repeat one list to match the length of another? Perhaps not the most efficient solution, but certainly short & simple: Gives "foobarfoobarfo". Doing, [3]*3 gives the result of [3,3,3], replacing this with n we get [3,3,3,3] (n times) Using a list comprehension we can go through each elem of the list and perform this operation, finally we need to flatten the list, which we can do by list(itertools.chain.from_iterable(lst)). Fast way to make list with same entry multiple times in Python? Modified 10 years, 6 months ago. But if the first number is less than the second number, the first number is unchanged. We will look at a basic sequence type: list. 592), Stack Overflow at WeAreDevelopers World Congress in Berlin, Temporary policy: Generative AI (e.g., ChatGPT) is banned. What's the translation of a "soundalike" in French? How did this hand from the 2008 WSOP eliminate Scott Montgomery? Repeat Elements of a List in Python - PythonForBeginners.com Asking for help, clarification, or responding to other answers. Why the ant on rubber rope paradox does not work in our universe or de Sitter universe? Using for loop Using for loop and range () Using while loop Using list comprehension Using for loop with lambda Using for loop with enumerate () Using numpy library Using the iter & next functions Python loop through a list Here we will discuss all 8 methods to loop through a list in Python. rev2023.7.24.43542. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. For immutable items, like None, bools, ints, floats, strings, tuples, or frozensets, you can do it like this: Note that this is usually only used with immutable items (strings, tuples, frozensets, ) in the list, because they all point to the same item in the same place in memory. With the for loop we can execute a set of statements, once for each item in a list, tuple, set etc. At first glance it seems that repeat is the fastest way to create a list with n identical elements: The function itertools.repeat doesn't actually create the list, it just creates an object that can be used to create a list if you wish! If the first number is greater than the second then they are subtracted and this new number replaces the first num. For me this worked perfectly, because I also wanted to sort the list after the multiplication. The function len () is one of Python's built-in functions. (Using zip), Keep looping until no further changes to list, Improving time to first byte: Q&A with Dana Lawson of Netlify, What its like to be on the Python Steering Council (Ep. What information can you get with only a private IP address. Asking for help, clarification, or responding to other answers. You can use the function with many different data types. Connect and share knowledge within a single location that is structured and easy to search. I'm reading about for loops right now, and I am curious if it's possible to do a for loop in Python like in Java. rev2023.7.24.43542. What loop can I use that runs through the entire list? The linked question is about numpy arrays, this one is about python lists. Can you please post an example and expected output with string values? Find centralized, trusted content and collaborate around the technologies you use most. This would create abcabcabcabc - Marcus Lind. The challenge is simple: given an input list a and another list b, repeat a until it is longer than b. Maybe you can try again and help me? I have a list [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] and I want to repeat a list n times. How can I update this to get the desired output? Looping Through a String Now, I have to understand what you are doing <3 :D, I think you misunderstood the question dear friend, I'm sorry somebody downvoted you! Does anyone know what specific plane this is a model of? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Could ChatGPT etcetera undermine community by making statements less significant for us? Not the answer you're looking for? If M is greater than the length of the word. First off, to repeat a string an integer number of times, you can use overloaded multiplication: So, to repeat a string until it's at least as long as the length you want, you calculate the appropriate number of repeats and put it on the right-hand side of that multiplication operator: Then, you can trim it to the exact length you want with an array slice: Alternatively, as suggested in pillmod's answer that probably nobody scrolls down far enough to notice anymore, you can use divmod to compute the number of full repetitions needed, and the number of extra characters, all at once: So, pillmod's version is something like 40% slower, which is too bad, since personally I think it's much more readable. Here is the code I have written to obtain the initial list from user input: This applies some function f to x until it is told to stop: An alternative to yield x is to save the results into a list using xs.append(x), and then to return that list once done: For your specific problem, one can craft a function "f", which we will call "run_iteration", as follows: Now, one simply needs to plug in run_iteration into accumulate_until: Printing out the results in a human-readable manner: Thanks for contributing an answer to Stack Overflow! unique Find the unique elements of an array. - how to corectly breakdown this sentence. Is there an exponential lower bound for the chromatic number? Whatever the list of nums is, the last number remains same. If your list is larger, you can use a more efficient key for the sort, like a dictionary which stores the elements and keys and their index as values. Repeat length of list on Python? The problem with the former is that it resolves your iterable into a tuple by merit of the unpacking operator which partially defeats the wonderfully laziness of, Repeat a list within a list X number of times, Best way to extend a list with itself N times. In Python, how do I create a string of n characters in one line of code? Release my children from my debts at the time of my death. Possible Duplicate: What happens if sealant residues are not cleaned systematically on tubeless tires used for commuters? You only have to use it in Python 3 (or in modules that have from __future__ import division) but you can use it regardless. How can I convert this half-hot receptacle into full-hot while keeping the ceiling fan connected to the switch? How can the language or tooling notify the user of infinite loops? This one repeat the string X times, it does not repeat it until X length. Keep looping until no further changes to list. Do I have a misconception about probability? [duplicate], Best way to extend a list with itself N times, Improving time to first byte: Q&A with Dana Lawson of Netlify, What its like to be on the Python Steering Council (Ep. A car dealership sent a 8300 form after I paid $10k in cash for a car. Who counts as pupils or as a student in Germany? In my Python 3 script, I am trying to make a combination of three numbers from three different lists based on inputs. python - Repeat list to max number of elements - Stack Overflow Guess I have to read up on what a standard library is. I have found the repeat function in Numpy, but one is only able to specify number of times to repeat. 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. Is there a better (more pythonic) way to do this? Movie about killer army ants, involving a partially devoured cow in a barn and a scene with a man driving around dropping dynamite into ant hills. minimalistic ext4 filesystem without journal and other advanced features, St. Petersberg and Leningrad Region evisa. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing, For those interested in efficiency, this is one of the (if not, pandas.Index.repeat just a call to np.repeat. How can I convert this half-hot receptacle into full-hot while keeping the ceiling fan connected to the switch? If a crystal has alternating layers of different atoms, will it display different properties depending on which layer is exposed? What information can you get with only a private IP address? Way to assign domain and/or value restrictions to multiple variables at once? Repeat values in array until specific length - Georgy. Not the answer you're looking for? Python For Loops - W3Schools : Is there a similar way in Python to do this? minimalistic ext4 filesystem without journal and other advanced features. This is often called a Python 3 feature, but according to PEP 238, it was introduced all the way back in Python 2.2. Try to avoid using explicit indexing into the list. Not a duplicate from my perspective. Find centralized, trusted content and collaborate around the technologies you use most. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Python3 list = [1, 3, 5, 7, 9] for i in list: print(i) Output: 1 3 5 7 9 # Input n = 5 List : [34 56 20 90 100] Round 1 : [34 36 20 90 100] Round 2 : [34 16 20 90 100] Round 3 : [18 16 20 90 100] Round 4 : [2 16 20 90 100] # Output No. Repeat Elements Of a List Using the extend () Method Using the * Operator Conclusion How To Repeat Elements of a List in Python To repeat the elements in a list in Python, we insert all the existing elements of a list into the same list. The need for this is rare: This is sometimes used to map an iterable into a list of lists: We can see that a_list contains the same range iterator four times: I've used Python for a long time now, and I have seen very few use-cases where I would do the above with mutable objects. Is not listing papers published in predatory journals considered dishonest? "Print this diamond" gone beautifully wrong. Example Get your own Python Server Print each fruit in a fruit list: fruits = ["apple", "banana", "cherry"] for x in fruits: print(x) Try it Yourself The for loop does not require an indexing variable to set beforehand. Generate a repeating index for length of list. Find centralized, trusted content and collaborate around the technologies you use most. Note: For more information, refer to Python Itertools repeat () How to get resultant statevector after applying parameterized gates in qiskit? The outer loop iterates through each element of test_list, and the inner loop iterates K times to repeat each element. How to repeat a string in python to a certain length. Could ChatGPT etcetera undermine community by making statements less significant for us? Let's see all the different ways to iterate over a list in Python, and performance comparison between them. A Simple for Loop Using a Python for loop is one of the simplest methods for iterating over a list or any other sequence (e.g. Connect and share knowledge within a single location that is structured and easy to search. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. rev2023.7.24.43542. How can kaiju exist in nature and not significantly alter civilization? Apr 9, 2019 at 7:01. How to automatically change the name of a file on a daily basis. Yes, that works, but how do you know that n suffices for the length you chose? If start is non-zero, then elements from the iterable are skipped until start is reached. Term meaning multiple different layers across many eras? Find centralized, trusted content and collaborate around the technologies you use most. Python: Repeat elements in a list comprehension? Can someone help me understand the intuition behind the query, key and value matrices in the transformer architecture? "Print this diamond" gone beautifully wrong. Circlip removal when pliers are too large, Movie about killer army ants, involving a partially devoured cow in a barn and a scene with a man driving around dropping dynamite into ant hills. For example: Edit: actually to my surprise, this is faster than the currently accepted solution (the 'repeat_to_length' function), at least on short strings: Presumably if the string was long, or length was very high (that is, if the wastefulness of the string * length part was high) then it would perform poorly. Then we put this all together. Ask Question Asked today Modified today Viewed 45 times -2 I have two lists: A = ['a', 'b', 'c', 'd', 'e'] B = ['c', 'a', 't'] How could I repeat the items of B to match the length of A? Method 1: Define a function that will take a word, m, and n values as arguments. Here are three ways one can create a list with a single element repeated 'n' times. python - Creating for loop until list.length - Stack Overflow The short answer is to use the for loop to loop over a List variable and print it in the output. Here a more "explicit" version that works with any length of LA. Making statements based on opinion; back them up with references or personal experience. For example, if n = 2 I want [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9] as output. I would say - do not try to write Java-like code in python. Iterate over a list in Python - GeeksforGeeks Asking for help, clarification, or responding to other answers. rev2023.7.24.43542. How to create an overlapped colored equation? That's even more important here, given how many answers have already been received. Connect and share knowledge within a single location that is structured and easy to search. What is a clean "pythonic" way to implement multiple constructors? Is that really what you want? The outer list stores four references to the same inner list. What is the smallest audience for a communication that has been deemed capable of defamation? "abc", 4 would expect "abca". But I still don't see why you can't use. You should note that if e is for example an empty list you get a list with n references to the same list, not n independent empty lists. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. [duplicate] Ask Question Asked 10 years, 6 months ago. Can a Rogue Inquisitive use their passive Insight with Insightful Fighting? How to generate list with repeating items? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. How to create an overlapped colored equation? 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. :). and length . Why is "1000000000000000 in range(1000000000000001)" so fast in Python 3? Is saying "dot com" a valid clue for Codenames? 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 R there is the rep function that allows you to repeat a vector, and with the additional argument length.out one is able to specify the length of the final vector/array, e.g. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Why is a dedicated compresser more efficient than using bleed air to pressurize the cabin? Is there a word in English to describe instances where a melody is sung by multiple singers/voices? How high was the Apollo after trans-lunar injection usually? You could add a switch between the two versions based on the input and output lengths for maximum optimization. How to repeat each of a Python list's elements n times with itertools only? without numpy, you can use the builtin itertools module, With a simple list comprehension (without even itertools). What loop can I use that runs through the entire list? As mentioned above, if e is an empty list. itertools. These are useful in many situations like going through every element of a list, doing an operation on a range of values, etc. You can use numpy.repeat easily. Avoiding memory leaks and using pointers the right way in my binary search tree implementation - C++. Python | Repeat each element K times in list - GeeksforGeeks Python's zip () function creates an iterator that will aggregate elements from two or more iterables. Conclusions from title-drafting and question-content assistance experiments Is there a more efficent way to extend a string? What is an efficient way to repeat a string to a certain length? Does this definition of an epimorphism work? I dont know why someone downvoted without even stating the reason. Mediation analysis with a log-transformed mediator. St. Petersberg and Leningrad Region evisa. To learn more, see our tips on writing great answers. What should I do after I found a coding mistake in my masters thesis? @stwhite So you want to preserve the order or "occurrence"? Was the release of "Barbie" intentionally coordinated to be on the same day as "Oppenheimer"? How can kaiju exist in nature and not significantly alter civilization? Python Loops - W3Schools @Timo. Python - itertools.repeat() - GeeksforGeeks Introduction to Loops in Python In programming, the loops are the constructs that repeatedly execute a piece of code based on the conditions. Is there an equivalent of the Harvard sentences for Japanese? What information can you get with only a private IP address? Iterating over a simple list. How did this hand from the 2008 WSOP eliminate Scott Montgomery? This would also work for other sequences, like tuples, but is not lazy like the itertools.chain.from_iterable and itertools.repeat method). Can a creature that "loses indestructible until end of turn" gain indestructible later that turn? python - Keep looping until no further changes to list - Stack Overflow Does the US have a duty to negotiate the release of detained US citizens in the DPRK? Is there a similar way in Python to do this? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Works with any order, sorts on the original order. How to Create a Repeat List with List Comprehension? python: how to identify if a variable is an array or a scalar. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I wrote the following simple procedure 592), Stack Overflow at WeAreDevelopers World Congress in Berlin, Temporary policy: Generative AI (e.g., ChatGPT) is banned. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. I think you need to use. For base Python 2.7: from itertools import repeat def expandGrid(**kwargs): # Input is a series of lists as named arguments # output is a dictionary defining each combination, preserving names # # lengths of each input list listLens = [len(e) for e in kwargs.itervalues()] # multiply all list lengths together to get total number of combinations . This module works as a fast, memory-efficient tool that is used either by themselves or in combination to form iterator algebra. Python How to repeat a list's elements in another list content until the length of the second list fulfilled? There are multiple ways to iterate over a list in Python. 592), Stack Overflow at WeAreDevelopers World Congress in Berlin, Temporary policy: Generative AI (e.g., ChatGPT) is banned. Creating a list, then changing one elem, and the whole list gets changed? Term meaning multiple different layers across many eras? and length defines the maximum length you want to keep. How can kaiju exist in nature and not significantly alter civilization? Find centralized, trusted content and collaborate around the technologies you use most. Conclusions from title-drafting and question-content assistance experiments python - check at the end of the loop if need to run again, Stopping a while loop when a certain element of the list is reached. E.g. There are several possible reasons for this, starting with its compiling to about 40% more bytecode instructions. What's the DC of Devourer's "trap essence" attack? Is it better to use swiss pass or rent a car? Depending on your use-case, you want to use different techniques with different semantics. You could learn about Python loops here: rev2023.7.24.43542. It will first create a list according to n and then slice it to the length you want.. Let's try that again, but converting to a list: So if you want a list, use [e] * n. If you want to generate the elements lazily, use repeat. Is there no way of doing this without importing a library? I'm new to Python. Looking for title of a short story about astronauts helmets being covered in moondust. Release my children from my debts at the time of my death. @MadPhysicist That switch between the two versions would probably add about as much overhead, as the division in Jason Scheirer's answer costs. If you only have the number, that would be: The _ is not really special, but your coding environment style checker will probably complain if you don't intend to use the variable and use any other name. Can a creature that "loses indestructible until end of turn" gain indestructible later that turn? This is especially important for members of our community who are beginners, and not familiar with the syntax. In addition, assigning variables (and reserving their storage) is quite slow in Python. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Ubuntu 23.04 freezing, leading to a login loop - how to investigate? The most readable/intuitive so far, in my opinion. Here v take the input n from the user and this n is the length of the list. How can the language or tooling notify the user of infinite loops? Loops Ansible Documentation Maybe using list comprehension? In Python you can iterate over the list itself: for item in my_list: #do something with item or to use indices you can use xrange (): for i in xrange (1,len (my_list)): #as indexes start at zero so you #may have to use xrange (len (my_list)) #do something here my_list [i] How high was the Apollo after trans-lunar injection usually? What's the DC of Devourer's "trap essence" attack? What information can you get with only a private IP address? If the generated list is large, it can be better to use a generator, so that items are generated one at a time on the fly without creating the whole large list in memory: How it works: itertools.cycle will cycle on lst indefinitely, and we keep only the len(lst) * times first items using itertools.islice, Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA.

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