How to write a NumPy array with Numeric and String data to a CSV file?

Last update on April 29 2025 13:00:08 (UTC/GMT +8 hours)

2. CSV with Mixed Data Write

Write a NumPy array with both numeric and string data to a CSV file.

Sample Solution:

Python Code:

import numpy as np
import csv

# Create a NumPy array with both numeric and string data
data_array = np.array([
    [1, 'Jorah Liina', 95.5],
    [2, 'Basil Aisha', 90.0],
    [3, 'Helga Myrthe', 80.0],
    [4, 'Lehi Piero', 91.5]
], dtype=object)

# Define the path to the output CSV file
csv_file_path = 'output.csv'

# Write the NumPy array to a CSV file
with open(csv_file_path, 'w', newline='') as csvfile:
    writer = csv.writer(csvfile, delimiter=',')
    for row in data_array:
        writer.writerow(row)

# Print a message indicating the CSV file has been written
print(f"Data has been written to {csv_file_path}")

Output:

Data has been written to output.csv

Content of  output.csv
----------------------------
1,Jorah Liina,95.5
2,Basil Aisha,90.0
3,Helga Myrthe,80.0
4,Lehi Piero,91.5

Explanation:

Import NumPy and CSV Libraries: Import the NumPy and CSV libraries to handle arrays and writing to CSV files.
Create a NumPy Array: Define a NumPy array with mixed data types (both numeric and string data), specifying dtype=object to handle different types within the array.
Define CSV File Path: Specify the path where the output CSV file will be saved.
Write Array to CSV File: Open the CSV file in write mode using open() and csv.writer(). Iterate through each row of the NumPy array and write it to the CSV file using writer.writerow().
Finally a message indicating that the data has been successfully written to the CSV file.

For more Practice: Solve these Related Problems:

Write a Numpy program to export a mixed-type array (numeric and string) to a CSV file ensuring proper quoting of strings.
Write a Numpy program to write a NumPy array containing both numbers and text to CSV and then verify the output by reading it back.
Write a Numpy program to convert a structured array with numeric and string fields to CSV with custom delimiters.
Write a Numpy program to write a mixed data NumPy array to CSV and then apply regex filtering on the exported file to extract numeric rows.

Go to:

Previous: How to read numeric data from a CSV file into a NumPy array?
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