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# Python | Variable list slicing

• Last Updated : 27 Mar, 2019

The problem of slicing a list has been dealt earlier, but sometimes we need to perform the slicing in variable lengths according to the input given in other list. This problem has its potential application in web development. Let’s discuss certain ways in which this can be done.

Method #1 : Using `itertools.islice()` + list comprehension
The list comprehension can be used to iterate through the list and the component issue is solved using the islice function.

 `# Python3 code to demonstrate``# variable length slicing``# using itertools.islice() + list comprehension``from` `itertools ``import` `islice`` ` `# initializing test list``test_list ``=` `[``1``, ``5``, ``3``, ``7``, ``8``, ``10``, ``11``, ``16``, ``9``, ``12``]`` ` `# initializing slice list ``slice_list ``=` `[``2``, ``1``, ``3``, ``4``]`` ` `# printing original list ``print``(``"The original list : "` `+` `str``(test_list))`` ` `# printing slice list ``print``(``"The slice list : "` `+` `str``(slice_list))`` ` `# using itertools.islice() + list comprehension``# variable length slicing``temp ``=` `iter``(test_list)``res ``=` `[``list``(islice(temp, part)) ``for` `part ``in` `slice_list]`` ` `# print result``print``(``"The variable sliced list is : "` `+` `str``(res))`
Output :
```The original list : [1, 5, 3, 7, 8, 10, 11, 16, 9, 12]
The slice list : [2, 1, 3, 4]
The variable sliced list is : [[1, 5], , [7, 8, 10], [11, 16, 9, 12]]
```

Method #2 : Using `zip() + accumulate()` + list slicing
Apart from using the list comprehension to perform the task of binding, this method uses zip function to hold sublist element together, accumulate function joins the elements, and slicing is used to construct the required slicing.

 `# Python3 code to demonstrate``# variable length slicing``# using zip() + accumulate() + list slicing``from` `itertools ``import` `accumulate`` ` `# initializing test list``test_list ``=` `[``1``, ``5``, ``3``, ``7``, ``8``, ``10``, ``11``, ``16``, ``9``, ``12``]`` ` `# initializing slice list ``slice_list ``=` `[``2``, ``1``, ``3``, ``4``]`` ` `# printing original list ``print``(``"The original list : "` `+` `str``(test_list))`` ` `# printing slice list ``print``(``"The slice list : "` `+` `str``(slice_list))`` ` `# using zip() + accumulate() + list slicing``# variable length slicing``res ``=` `[test_list[i ``-` `j: i] ``for` `i, j ``in` `zip``(accumulate(slice_list), slice_list)]`` ` `# print result``print``(``"The variable sliced list is : "` `+` `str``(res))`
Output :
```The original list : [1, 5, 3, 7, 8, 10, 11, 16, 9, 12]
The slice list : [2, 1, 3, 4]
The variable sliced list is : [[1, 5], , [7, 8, 10], [11, 16, 9, 12]]
```

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