How to delete last N rows from Numpy array?

In this article, we will discuss how to delete the last N rows from the NumPy array.

Method 1: Using Slice Operator

Slicing is an indexing operation that is used to iterate over an array.

 Syntax: array_name[start:stop]

where start is the start is the index and stop is the last index.

We can also do negative slicing in Python. It is denoted by the below syntax.

Syntax: array_name[: -n]

where, n is the number of rows from last to be deleted.

Example1:

We are going to create an array with 6 rows and 3 columns and delete last N rows using slicing.

Output:

👁 Image

Example 2: 

We use for loop to iterate over the elements and use the slice operator, we are going to delete the data and then print the data.

Output:

👁 Image

Example 3:

We can also specify the elements that we need and store them into another array variable using the slice operator. In this way, we will not get the last N rows (delete those).

Output:

[[21 7 8 9]
 [34 10 11 12]]

Method 2: Using numpy.delete() method

It is used to delete the elements in a NumPy array based on the row number.

Syntax: numpy.delete(array_name,[rownumber1,rownumber2,.,rownumber n],axis)

Parameters:

• array_name is the name of the array.
• row numbers is the row values
• axis specifies row or column
  • axis=0 specifies row
  • axis=1 specifies column

Here we are going to delete the last rows so specify the rows numbers in the list.

Example 1: Delete last three rows

Output:

[[21 7 8 9]
 [34 10 11 12]]

Example 2: Delete all rows

Output:

[ ]