NumPy Slicing 2d Array in Python

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by vsasikalabe dot icon Updated: May 3, 2023

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In Python, Slicing describes taking elements from one given index to another. You must select a row index and a column index [row_index, column_index]. We can use it to slice elements from two-dimensional arrays. We can use the NumPy slicing in a Python array to extract the wanted data from the original array. It is also called Python NumPy array Slicing. We can use NumPy array indexing to extract the data using the index value. In 2D numpy arrays, you should define row and column indexes for the element you want to execute. This array slicing is like indexing and slicing with Python lists, with differences. The resulting array is the same view as the original array when you slice a numpy array. It has the same data, accessed in a different order. You will change the corresponding elements in the original array to change the view.

Types of 2d array slicing:  

  • Flip vertically – np.flipud() means Up and Down.  
  • Flip horizontally – np.fliplr(), which means Left and Right.  
  • Flip ndarray along any axis – np.flip(), and we can also flip along many axes.  

We must pass two values for 1-D NumPy array Slicing (start and end index value followed by the array name). We should create a 3D array and apply the slice statement to perform a slice operation. The Numpy slicing is somewhat different from normal slicing. The code will begin by downloading the packages and importing the data into numpy arrays. Import the NumPy library by (import numpy as np). This library can create an N-dimensional array to perform linear operations. As discussed above, you must define one index value: the element's position in the array. We are following some rules to perform NumPy slicing under the NumPy documentation.

Array manipulation using NumPy:  

  • Addition – np.add(x,y)  
  • Subtraction – np.subtract(x,y)  
  • Multiplication – np.multiply(x,y)  
  • Divide – np.divide(x,y)  

NumPy Aggregate Functions:  

  • np.sum,, np.mean(), np.std()  
  • np.var(), np.min(), np.max(), np.all(), np.any()  

By providing an index range, we can slice a range of elements in an array. We can use negative slicing to slice an element from the end. The random is a module of the NumPy library. This module has certain functions which we can use for creating random numbers. The NumPy repeat function can repeat the numbers inside an array. It repeats the individual elements that are present in the array.  

Syntax of the Repeat Function:  

np.repeat (a = , repeats = ,axis = )  

  • np.repeat - The function name  
  • a - the input array you want to operate on (required)  
  • repeats - the number of times to repeat each element  
  • axis - which axis the elements to repeat.  

Finally, the print statement will print the 2-dimensional value of the array.  

This is an example of how to Slice the Numpy 2d Array in Python:  

Fig : Preview of the output that you will get on running this code from your IDE.



Follow the steps carefully to get the output easily.

  1. Download and Install the PyCharm Community Edition on your computer.
  2. Open the terminal and install the required libraries with the following commands.
  3. Install Numpy - pip install Numpy.
  4. Create a new Python file on your IDE.
  5. Copy the snippet using the 'copy' button and paste it into your Python file.
  6. Run the current file to generate the output.

I hope you found this useful.

I found this code snippet by searching for ' NumPy slicing squares in 2D array ' in Kandi. You can try any such use case!

Environment Tested

I tested this solution in the following versions. Be mindful of changes when working with other versions.

  1. PyCharm Community Edition 2022.3.1
  2. The solution is created in Python 3.11.1 Version
  3. Numpy 1.24.2 Version

Using this solution, we can able to do NumPy Slicing 2d Array in Python with simple steps. This process also facilities an easy way to use, hassle-free method to create a hands-on working version of code which would help us to do NumPy Slicing 2d Array in Python.

Dependent Libraries

numpyby numpy

Python doticonstar image 23755 doticonVersion:v1.25.0rc1doticon
License: Permissive (BSD-3-Clause)

The fundamental package for scientific computing with Python.


            numpyby numpy

            Python doticon star image 23755 doticonVersion:v1.25.0rc1doticon License: Permissive (BSD-3-Clause)

            The fundamental package for scientific computing with Python.

                      If you do not have numpy library that is required to run this code, you can install it by clicking on the above link.

                      You can search for any dependent library on kandi like numpy.


                      1. What is Python NumPy, and what advantages does it have over other libraries?  

                      NumPy is a Python library. We can perform operations over an array and Fourier transform. And over Linear algebra and matrices using NumPy. It consumes less memory for all mathematical operations. It has a better runtime speed when compared to other libraries.

                      2. How can I use the NumPy library to perform a slicing operation on a 2D array?  

                      We can perform the NumPy array slicing using the function's start, end, and step parameters. The Syntax is [start:stop: step].  

                      • Start – By default, and the index is 0.  
                      • Step – By default, the index is 1.  
                      • Stop – We can consider the index as the length of the array.  

                      3. What is the correct Python syntax for slicing operations on an N-dimensional array?  

                      By using index value the, Synax is,  



                      4. How does integer indexing work when dealing with a 2D array and its elements?  

                      We can index the 2D array with two subsets. 

                      1. Row  
                      2. Column  

                      It is zero-indexed. The counting starts with zero. Each element in an array must be the same type (primitive or object type).   

                      5. What should be my first index value when creating slices of a 2D array in Python NumPy?  

                      The first index value is zero when creating slices of a 2D array in Python NumPy.  

                      6. Is it possible to slice an N-dimensional array using something other than a tuple sequence object?  

                      Yes, slicing an N-dimensional array using the NumPy library is possible. Import the NumPy as np. It returns with the same data but in a completely different order. Now, we can perform all mathematical operations.  

                      7. How do I use Negative Slicing when working with many rows and columns in an N-dimensional array?

                      Negative slicing starts with the end of an array. The last element of the array will be the first index. For example,  

                      import numpy as np  

                      arr = np.array([10,20,30,40,50])  


                      The Output is 40.  


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