Python – Text Translation with mtranslate: A Line-by-Line Guide

Introduction

In this tutorial, we’ll translate text line-by-line from a file using the Python library mtranslate (Text Translation), saving the results to output.txt. We’ll enhance the process with tqdm for progress tracking, making this automated translation script both efficient and visible. Ideal for quick, general-purpose translations, this approach avoids costly APIs.

Setup and Imports

Start by importing the required libraries for our Python text translation task:

from mtranslate import translate
import os
import re
from tqdm import tqdm

Next, define dynamic file paths to keep the script portable:

base_dir = os.path.dirname(__file__)  # Get script directory
input_file = os.path.join(base_dir, 'input.txt')  # Source text file
output_file = os.path.join(base_dir, 'output.txt')  # Translated output file

The Translation Script

Here’s the complete script to read, translate, and write text with progress visibility:

from mtranslate import translate
import os
import re
from tqdm import tqdm

# Dynamic file paths
base_dir = os.path.dirname(__file__)
input_file = os.path.join(base_dir, 'input.txt')
output_file = os.path.join(base_dir, 'output.txt')

def translate_text(text, target_lang='en', source_lang='auto'):
    """Translate text using mtranslate, with error fallback."""
    try:
        return translate(text, target_lang, source_lang)
    except Exception as e:
        print(f"Translation error for '{text}': {e}")
        return text  # Fallback to original text

def contains_letters(text):
    """Check if text contains alphabetic characters."""
    return bool(re.search(r'[a-zA-Zа-яА-Я]', text))

# Language settings
source_lang = 'auto'  # Auto-detect source language
target_lang = 'en'    # Target language: English

try:
    # Pre-read lines for accurate progress tracking
    with open(input_file, "r", encoding="utf-8") as infile:
        lines = infile.readlines()

    with open(output_file, "w", encoding="utf-8") as outfile:
        # Translate with progress bar
        for line in tqdm(lines, desc="Translating lines", unit="line"):
            line = line.strip()  # Clean whitespace
            if line:  # Skip empty lines
                if contains_letters(line):
                    translated_line = translate_text(line, target_lang, source_lang)
                    outfile.write(f"{translated_line}\n")
                else:
                    outfile.write(f"{line}\n")  # Non-alphabetic lines unchanged
    print(f"\nTranslation completed! Results saved to: {output_file}")

except FileNotFoundError:
    print(f"Error: '{input_file}' not found. Verify the file path.")
except Exception as e:
    print(f"Unexpected error: {e}")

How it works:

• Reads input.txt line-by-line.
• Translates only lines with letters, preserving others (e.g., numbers).
• Shows progress with tqdm.
• Saves results to output.txt.

Advantages

This mtranslate tutorial offers clear benefits:

• Simplicity: Add text to input.txt, run the script, and get results fast.
• Cost-Free: No API fees—just Python and mtranslate.
• Visibility: Progress tracking with tqdm keeps you informed.

While translations may lack professional polish, they suffice for general use in 2025.

Conclusion

This automated translation script using mtranslate and tqdm makes Python text translation accessible and efficient. Perfect for quick translations of text files, it’s a practical tool for developers, researchers, or anyone needing basic translation without complexity. Try it with your own input.txt and see the results!