The Numpy library in Python comes with a number of useful methods and techniques to work with and manipulate data in arrays. In this tutorial, we will look at how to get the first N elements of a one-dimensional Numpy Array with the help of some examples.
How to get the first n elements of a Numpy array?
To get the first n elements of a Numpy array, slice the array from index 0 to index n. The following is the syntax –
# first n elements of numpy array ar[:n]
This will give us the elements in the array starting from the element at index 0 up to (but not including) the element at index n.
Steps to get the first n elements in an array
Let’s now look at a step-by-step example of using the above syntax on a Numpy array.
Step 1 – Create a Numpy array
First, we will create a Numpy array that we’ll operate on.
import numpy as np # create numpy array ar = np.array([1, 5, 6, 3, 2, 4, 7]) # display the array print(ar)
[1 5 6 3 2 4 7]
Here, we used the
numpy.array() function to create a one-dimensional Numpy array containing some numbers. There are seven elements in the array.
Step 2 – Slice the array to get the first n elements
To get the first n elements of the above array, slice the array starting from the first element (0th index) up to (but not including) the element with the index n.
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For example, let’s get the first 3 elements from the array that we created in step 1.
# get first 3 elements of the array print(ar[0:3])
[1 5 6]
We get the first 3 elements of the array.
In the above code, you don’t need to explicitly specify 0 (since you’re slicing starting from the very first element of the array).
# get first 3 elements of the array print(ar[:3])
[1 5 6]
We get the same result as above.
For more on slicing Numpy arrays, refer to its documentation.
In this tutorial, we looked at how to get the first n elements of a one-dimensional Numpy array using slicing. The following is a short summary of the steps mentioned in the tutorial.
- Create a Numpy array (skip this step if you already have an array to operate on).
- Slice the array from index 0 to index n to get the first n elements of the array.
You might also be interested in –
- Numpy – Get Max Value in Array
- Get the Median of Numpy Array – (With Examples)
- Pandas – Select first n rows of a DataFrame
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