NumPy: Extract all the rows to compute the student weight from a given array (student information) where a specific column starts with a given character

Last update on August 29 2025 12:45:26 (UTC/GMT +8 hours)

Compute weight sum of rows where names match a condition.

Write a NumPy program to extract all the rows to compute the student weight from a given array (student information) where a specific column starts with a given character.

Sample Solution:

Python Code:

# Importing NumPy library
import numpy as np

# Setting printing options to display arrays with a maximum line width of 100
np.set_printoptions(linewidth=100)

# Creating a NumPy array containing student data with IDs, class, names, and weights
student = np.array([
    ['01', 'V', 'Debby Pramod', 30.21],
    ['02', 'V', 'Artemiy Ellie', 29.32],
    ['03', 'V', 'Baptist Kamal', 31.00],
    ['04', 'V', 'Lavanya Davide', 30.22],
    ['05', 'V', 'Fulton Antwan', 30.21],
    ['06', 'V', 'Euanthe Sandeep', 31.00],
    ['07', 'V', 'Endzela Sanda', 32.00],
    ['08', 'V', 'Victoire Waman', 29.21],
    ['09', 'V', 'Briar Nur', 30.00],
    ['10', 'V', 'Rose Lykos', 32.00]
])

# Displaying the original array
print("Original array:")
print(student)

# Finding the total weight of students whose names start with a specific character ('E')
char = 'E'
result = student[np.char.startswith(student[:, 2], char)]
print("\nTotal weight, where student name starts with", char)
print(np.round(result[:, 3].astype(float).sum(), 2))

# Finding the total weight of students whose names start with a specific character ('D')
char = 'D'
result = student[np.char.startswith(student[:, 2], char)]
print("\nTotal weight, where student name starts with", char)
print(np.round(result[:, 3].astype(float).sum(), 2))

Sample Output:

Original array:
[['01' 'V' 'Debby Pramod' '30.21']
 ['02' 'V' 'Artemiy Ellie' '29.32']
 ['03' 'V' 'Baptist Kamal' '31.0']
 ['04' 'V' 'Lavanya Davide' '30.22']
 ['05' 'V' 'Fulton Antwan' '30.21']
 ['06' 'V' 'Euanthe Sandeep' '31.0']
 ['07' 'V' 'Endzela Sanda' '32.0']
 ['08' 'V' 'Victoire Waman' '29.21']
 ['09' 'V' 'Briar Nur' '30.0']
 ['10' 'V' 'Rose Lykos' '32.0']]

Total weight, where student name starting with E
63.0

Total weight, where student name starting with D
30.21

For more Practice: Solve these Related Problems:

Write a NumPy program to compute the sum of weight values from rows of a structured array where the name field starts with a specified letter using np.char.startswith and np.sum.
Create a function that filters rows based on a condition applied to the name column and then calculates the total weight from a corresponding weight column.
Implement a solution that uses advanced indexing to extract rows meeting the name criteria and aggregates their weight values.
Test the weight-sum function on arrays containing missing or non-numeric weight entries to ensure robust handling and error checking.

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