# NumPy selecting specific column index per row by using a list of indexes

Given a NumPy array, we have to select specific column index per row by using a list of indexes. By Pranit Sharma Last updated : October 08, 2023

NumPy is an abbreviated form of Numerical Python. It is used for different types of scientific operations in python. Numpy is a vast library in python which is used for almost every kind of scientific or mathematical operation. It is itself an array which is a collection of various methods and functions for processing the arrays.

## Problem statement

Suppose we are given a two-dimensional NumPy array with some rows and columns. We need to select some specific column based on the index which is itself an element of the list given to use.

## Selecting specific column index per row by using a list of indexes

For this purpose, we will use np.arrange method() which will take a total length of the array and the index list and returns evenly spaced values within a given interval.

Let us understand with the help of an example,

## Python program to select specific column index per row by using a list of indexes

```# Import numpy
import numpy as np

# Creating a numpy array
arr = np.array([[2, 7, 3],[4, 2, 1],[7, 3, 6]])

# Display original array
print("Original Array:\n",arr,"\n")

# Creating a list of indices
lst = [1,0,2]

# using arrange method
res = arr[np.arange(len(arr)), lst]

# Display result
print("Result is:\n",res,"\n")
```

### Output

The output of the above program is: