 # Python | Repeat each item K times in the list

Method # 1: Using a list comprehension
This particular task usually requires 2 loops and a list comprehension can do this particular task in one line and therefore reduce the number of lines of code and improve code readability.

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

Exit:

``` 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 built-in functions of the itertools library. The repeat function, as the name suggests, performs the task of repeating and grouping into a list using the from_iterable function.           ` # Python3 demo code `  ` # repeat element K times `  ` # use itertools.chain.from_iterable () + itertools.repeat () `   ` import ` ` itertools `    ` # initializing the list of lists `   ` test_list ` ` = ` ` [` ` 4 ` `, ` ` 5 ` `, ` ` 6 ` `] `     ` # print the original list `   ` print ` ` (` `" The original list: "` ` + ` ` str ` ` (test_list)) `    ` # declaring the repetition rate `   ` 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)) `  ` `  ` # print 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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