How to repeat a list in python
Depending on your use-case, you want to use different techniques with different semantics. Show
Multiply a list for Immutable itemsFor 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. I use this frequently when I have to build a table with a schema of all strings, so that I don't have to give a highly redundant one to one mapping.
Multiply the list where we want the same item repeatedMultiplying a list gives us the same elements over and over. The need for this is rare:
This is sometimes used to map an iterable into a list of lists:
We can see that
Mutable itemsI'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. Instead, to get, say, a mutable empty list, set, or dict, you should do something like this:
The underscore is simply a throwaway variable name in this context. If you only have the number, that would be:
The Caveats for using the immutable method with mutable items:Beware doing this with mutable objects, when you change one of them, they all change because they're all the same object:
foo now returns:
But with immutable objects, you can make it work because you change the reference, not the object:
But again, mutable objects are no good for this, because in-place operations change the object, not the reference: In python, we use lists for various tasks. We have already discussed various operations on lists like counting the frequency of elements in a list or reversing a list. In this article, we will discuss three ways to Repeat each element k times in a list in python. How to Repeat Each Element k Times in a List in Python?To repeat the elements in a list in python, we insert the elements of a given list to a new list repeatedly. To repeat each element k times in a list, we will insert each element of the existing k times in the new list. For instance, If we have a list To perform this operation, we can use the for loop or list comprehension with the Repeat Each Element k Times in a List Using For Loop and append() MethodThe
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To repeat each element k times in a list, We will first create an empty list named
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Repeat Each Element k Times in a List Using List ComprehensionInstead of using for loop, we can use list comprehension to repeat each element k times in a list as follows.
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Using itertools.chain.from_iterable() and itertools.repeat() MethodInstead of explicitly adding elements to the new list to repeat them, we can use the The
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The
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To repeat each element k times in a list, we will first create an list for each element of the existing list using the
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ConclusionIn this article, we have discussed three ways to repeat each element k times in a list in python. To read more about lists in python, you can read this article on how to delete last element from a list in python. Recommended Python TrainingCourse: Python 3 For Beginners Over 15 hours of video content with guided instruction for beginners. Learn how to create real world applications and master the basics. What is repetition of list in Python?Lists can be created using the repetition operator, *. We are accustomed to using the * symbol to represent multiplication, but when the operand on the left side of the * is a list, it becomes the repetition operator. The repetition operator makes multiple copies of a list and joins them all together.
How do you replicate a list?The replication of list of a list can be created by using rep function. For example, if we have a list called x and we want to create five times replicated list of this list then we can use the code rep(list(x),5).
How do I make a list of the same values?Use the multiplication operator to create a list with the same value repeated N times in Python, e.g. my_list = ['abc'] * 3 . The result of the expression will be a new list that contains the specified value N times. Copied!
Can a list in Python have repeated elements?Python list can contain duplicate elements.
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