# Array Slicing in Python

Slicing is used to retrieve set of values from an array.

Slicing on 1-Dimensional Array

It is defined as below

arrayName[start:end:step]

start — Starting Index, inclusive. It could be optional as well, default value is 0.

end — Ending Index, exclusive. It could be optional as well, default value is length of the array.

step — Optional field, it is 1 by default.

Example

`array1 = [‘a’, ‘b’, ‘c’,’d’,’e’,’f’]`

If we need only the elements b,c,d from the array, then we write as below

`array1[1:4] Output: ['b', 'c', 'd']`

where 1 is the starting index, 4 is the ending index which is excluded and step is 1 by default.

`array1[1:4:2]Output: ['b', 'd']array1[1:]Output: ['b', 'c', 'd', 'e', 'f']array1[:4]Output: ['a', 'b', 'c', 'd']array1[:]Output: ['a', 'b', 'c', 'd', 'e', 'f']`

Slicing on 2-Dimensional Array

2D Array consists of rows and columns. So, in order to slice a 2D array, we have to perform slicing operation on both rows and columns. The syntax is as below

`arrayname[start:end:step, start:end:step]`

First one is for rows and second one is for columns

`# importing numpy package for creating 2D Arrayimport numpy as np#Creating 2D Arrayarray2 = np.array([[1,2,3,4],           [2,3,4,5],          [3,4,5,6],          [4,5,6,7]         ])#Slicing Operation on 2D Array# to return all rows and only first two columns from the array defined.array2[:,:2]Output: array([[1, 2],       [2, 3],       [3, 4],       [4, 5]])# to return from second row and first two columnsarray2[1:,:2]Output: array([[2, 3],       [3, 4],       [4, 5]])`