np.ix_() for open mesh indexing in NumPy - Mini Project: Build & Apply

Using np.ix_() for Open Mesh Indexing

📖 Scenario: Imagine you have a grid of temperature readings from a weather station. You want to select specific rows and columns to analyze a smaller area.

🎯 Goal: You will create a 2D NumPy array representing temperature data, select specific rows and columns using np.ix_(), and print the selected subgrid.

📋 What You'll Learn

Create a 2D NumPy array called temperature_grid with exact values

Create two 1D arrays called row_indices and col_indices with exact values

Use np.ix_() with row_indices and col_indices to select a subgrid

Print the selected subgrid

💡 Why This Matters

🌍 Real World

Selecting specific rows and columns from a grid is common in weather data analysis, image processing, and scientific simulations.

💼 Career

Understanding how to use <code>np.ix_()</code> helps data scientists efficiently extract and analyze parts of large datasets.

1

Create the temperature grid

Create a 2D NumPy array called temperature_grid with these exact values: [[30, 32, 31, 29], [28, 27, 26, 25], [24, 23, 22, 21], [20, 19, 18, 17]]

NumPy

import numpy as np
# Create the 2D array temperature_grid with the exact values
# Your code here

Need a hint?

Use np.array() and pass the list of lists with the exact numbers.

2

Create row and column index arrays

Create a 1D NumPy array called row_indices with values [1, 3] and another 1D NumPy array called col_indices with values [0, 2]

NumPy

import numpy as np

temperature_grid = np.array([[30, 32, 31, 29], [28, 27, 26, 25], [24, 23, 22, 21], [20, 19, 18, 17]])
# Create row_indices with [1, 3]
# Create col_indices with [0, 2]
# Your code here

Need a hint?

Use np.array() to create both row_indices and col_indices.

3

Select the subgrid using np.ix_()

Use np.ix_() with row_indices and col_indices to select a subgrid from temperature_grid and assign it to selected_subgrid

NumPy

import numpy as np

temperature_grid = np.array([[30, 32, 31, 29], [28, 27, 26, 25], [24, 23, 22, 21], [20, 19, 18, 17]])

row_indices = np.array([1, 3])
col_indices = np.array([0, 2])
# Use np.ix_() with row_indices and col_indices to select subgrid
# Your code here

Need a hint?

Use temperature_grid[np.ix_(row_indices, col_indices)] to select the subgrid.

4

Print the selected subgrid

Print the variable selected_subgrid to display the selected temperature subgrid

NumPy

import numpy as np

temperature_grid = np.array([[30, 32, 31, 29], [28, 27, 26, 25], [24, 23, 22, 21], [20, 19, 18, 17]])

row_indices = np.array([1, 3])
col_indices = np.array([0, 2])

selected_subgrid = temperature_grid[np.ix_(row_indices, col_indices)]
# Print selected_subgrid
# Your code here

Need a hint?

Use print(selected_subgrid) to show the result.