# Python | Repeat each element K times in list

Many times we have this particular use-case in which we need to repeat each element of list K times. The problems of making a double clone have been discussed but this problem extends to allow a flexible variable to define the number of times the element has to be repeated. Let’s discuss certain ways in which this can be performed.

Method #1 : Using list comprehension
This particular task requires generally 2 loops and list comprehension can perform this particular task in one line and hence reduce the lines of codes and improving code readability.

 `# Python3 code to demonstrate  ` `# repeat element K times ` `# using list comprehension ` ` `  `# initializing list of lists ` `test_list ``=` `[``4``, ``5``, ``6``] ` ` `  `# printing original list  ` `print``(``"The original list : "` `+`  `str``(test_list)) ` ` `  `# declaring magnitude of repetition ` `K ``=` `3` ` `  `# using list comprehension ` `# repeat elements K times ` `res ``=`  `[ele ``for` `ele ``in` `test_list ``for` `i ``in` `range``(K)] ` ` `  `# printing result  ` `print``(``"The list after adding elements :  "` `+` `str``(res)) `

Output :

```The original list : [4, 5, 6]
The list after adding elements :  [4, 4, 4, 5, 5, 5, 6, 6, 6]
```

Method #2 : Using `itertools.chain.from_iterable() + itertools.repeat()`
This particular problem can also be solved using python inbuilt functions of itertools library. The repeat function, as name suggests does the task of repetition and grouping into a list is done by the from_iterable function.

 `# Python3 code to demonstrate  ` `# repeat element K times ` `# using itertools.chain.from_iterable() + itertools.repeat() ` `import` `itertools ` ` `  `# initializing list of lists ` `test_list ``=` `[``4``, ``5``, ``6``] ` ` `  `# printing original list  ` `print``(``"The original list : "` `+`  `str``(test_list)) ` ` `  `# declaring magnitude of repetition ` `K ``=` `3` ` `  `# using itertools.chain.from_iterable()  ` `# + itertools.repeat() repeat elements K times ` `res ``=` `list``(itertools.chain.from_iterable(itertools.repeat(i, K) ` `                                           ``for` `i ``in` `test_list)) ` ` `  `# printing result  ` `print``(``"The list after adding elements :  "` `+` `str``(res)) `

Output :

```The original list : [4, 5, 6]
The list after adding elements :  [4, 4, 4, 5, 5, 5, 6, 6, 6]
```

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