In this article, we will learn about the Python slice() function with the help of multiple examples.
Example
Python3
String = 'Hello World'
slice_obj = slice(5,11)
print(String[slice_obj])
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Output:
World
A sequence of objects of any type (string, bytes, tuple, list, or range) or the object which implements __getitem__() and __len__() method then this object can be sliced using slice() method.
Python slice() Function Syntax
Syntax: slice(start, stop, step)
Parameters:
- start: Starting index where the slicing of object starts.
- stop: Ending index where the slicing of object stops.
- step: It is an optional argument that determines the increment between each index for slicing.
Return Type: Returns a sliced object containing elements in the given range only.
Note: If only one parameter is passed, then the start and step are considered to be None.
slice() Function in Python Examples
Python slice string
We have created the string GeeksforGeeks, and we are using the slice function to slice the string. The first slice function is slicing the string to the 2nd index, the second slice function is used to slice the string to the 4th index with a leaving 2nd index. Finally, we are printing both sliced strings in the terminal.
Python3
String = 'GeeksforGeeks'
slice_obj1 = slice(3)
slice_obj2 = slice(1, 5, 2)
print("String slicing")
print(String[slice_obj1])
print(String[slice_obj2])
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Output:
String slicing
Gee
ek
Python slice list or Python slice array
We have created the list [1,2,3,4,5], and we are using the slice function to slice the list. The first slice function is slicing the list to the 2nd index, the second slice function is used to slice the list to the 4th index with a leaving 2nd index. Finally, we are printing both sliced lists in the terminal.
Python3
L = [1, 2, 3, 4, 5]
slice_obj1 = slice(3)
slice_obj2 = slice(1, 5, 2)
print("List slicing")
print(L[slice_obj1])
print(L[slice_obj2])
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Output:
List slicing
[1, 2, 3]
[2, 4]
Python slice tuple
We have created a tuple of 5 numbers, and we are using the slice function 2 times, first slice function is slicing the tuple to 2 indexes, and the second slice function is slicing the tuple to 4 indexes and every second element is sliced.
Python3
T = (1, 2, 3, 4, 5)
slice_obj1 = slice(3)
slice_obj2 = slice(1, 5, 2)
print("Tuple slicing")
print(T[slice_obj1])
print(T[slice_obj2])
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Output:
Tuple slicing
(1, 2, 3)
(2, 4)
Negative indexing
In Python, negative sequence indexes represent positions from the end of the array. slice() function can also have negative values. In that case, the iteration will be performed backwards i.e. from end to start.
Get a sub-list using a negative index with a slice()
In the example, We have created a list with values ‘a’, ‘b’, ‘c’, ‘d’, ‘e’, ‘f’.We are slicing the string from the 2nd index from the last and going to the 6th index from the last, with the hop of -1.
Python3
l = ['a', 'b', 'c', 'd', 'e', 'f']
slice_obj = slice(-2, -6, -1)
print("list slicing:", l[slice_obj])
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Output:
list slicing: ['e', 'd', 'c', 'b']
Get a sub-string using a negative index with a slice()
We have created a string of letters, we are using the slice function with a negative index of -1 to slice the string apart from the last letter.
Python3
s = "geeks"
slice_obj = slice(-1)
print("string slicing:", s[slice_obj])
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Output:
string slicing: geek
Get a sub-tuple using a negative index with slice()
In the code, slice_obj = slice(-1, -3, -1) creates a slice object that will slice the tuple starting from the second-to-last element (index -1), up to (but not including) the fourth-to-last element (index -3), with a step size of -1. This means that the sliced tuple will contain the elements [9, 7], in reverse order.
Python3
t = (1, 3, 5, 7, 9)
slice_obj = slice(-1, -3, -1)
print("tuple slicing:", t[slice_obj])
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Output:
tuple slicing: (9, 7)
Using Indexing Syntax for Slicing with String
In the example, we have created a list named slice_str with the value ‘GeeksForGeeks‘.The first slice is printing the value till the 4 indexes and the second slice is printing till the 5th index with a hop of every 2nd index.
Python3
slice_str = 'GeeksForGeeks'
print(slice_str[0:5])
print(slice_str[1:6:2])
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Output:
Geeks
ekF
Using Indexing Syntax for Slicing with List
In the example, we have created a list named slice_list and we have inserted [‘G’,’e’,’e’,’k’,’s’,’F’,’o’,’r’,’G’,’e’,’e’,’k’,’s’] these values to our list. The first slice is printing the value till 4 indexes and the second slice is printing till the 5th index with a hop of every 2nd index.
Python3
slice_list = ['G','e','e','k','s','F','o','r','G','e','e','k','s']
print(slice_list[0:5])
print(slice_list[1:6:2])
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Output:
['G', 'e', 'e', 'k', 's']
['e', 'k', 'F']
Slicing and modifying a list
In the example, we have created a list of numbers named slice_numbers which consists of 5 variables [1,2,3,4,5] in it.Then we are slicing the list from index 1 to 3 and also modify its value from [1,2,3] to [10,20,30] and finally, we are printing the slice_numbers list.
Python3
slice_numbers = [1, 2, 3, 4, 5]
print("slice_number before slicing and modfication : ",end=' ')
print(slice_numbers)
slice_numbers[1:4] = [10, 20, 30]
print("slice_number after slicing and modfication : ",end=' ')
print(slice_numbers)
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Output:
slice_number before slicing and modfication : [1, 2, 3, 4, 5]
slice_number after slicing and modfication : [1, 10, 20, 30, 5]