Print string to text file

Context manager mastery and file handling

Context managers (with keyword in Python) ensure that files are properly closed after operations, avoiding resource leaks.

Cooking strings with formatting techniques

String parsing is an art. Python 3.6's f-Strings provide a slick way to bake variables into strings:

# Say our coder is buying another Python book
total_amount = 49.99
with open('purchase.txt', 'w') as f:
    f.write(f"Purchase Amount: {total_amount}")  # This will print: "Purchase Amount: 49.99"
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The good old str.format() and % operator are like that rusty hammer in the tool-box that always gets the job done, providing backwards compatibility:

# Old is gold!
with open('purchase.txt', 'w') as f:
    f.write("Purchase Amount: {}".format(total_amount))  # Python 2.6+ folks

with open('purchase.txt', 'w') as f:
    f.write("Purchase Amount: %s" % total_amount)  # When all hell breaks loose
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File handling with pathlib

The pathlib module is like a Swiss Army Knife for file operations in Python 3.4 and above:

from pathlib import Path

Path('hello_world.txt').write_text('Hello, world!')  # I just did a write operation, how cool is that?
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It's got everything, from explicit file opening and closing to reducing syntax errors.

Expanding writing abilities

Python 3's print function can be pointed to a file with its file parameter:

with open('log.txt', 'w') as f:
    print("Another error has been logged!", file=f)  # Debuggers gonna love this line
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Dealing with multi-value nightmares

When handling multiple values, tuple formatting, combined with the % operator can be a heaven-sent knight in shining armor:

total, tax = 200, 30
with open('summary.txt', 'w') as f:
    f.write("Total: %f, Tax: %f" % (total, tax))  # Taxes, amirite?
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Mighty arrays with numpy

Working with numerical arrays? numpy.savetxt should be your poison:

import numpy as np
data = np.array([[22, 7], [3.14, 2.718]])

# Pi vs Euler, Round 1!
np.savetxt('pi_vs_euler.txt', data, fmt='%f')
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Specific string formatting can ensure your data files are both a joy to read and parse in the future.

Concatenation: When simple is better

In some cases, string concatenation is your best buddy:

with open('greet.txt', 'w') as file:
    file.write('Hello' + ', ' + 'world!')  # 'Hello, world!', the phrase that made history
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However, keep in mind that this method isn't the most efficient for large-scale projects.

No-context operation

In some rare conditions, if you can't use a context manager, always remember to manually close the file:

f = open('misc.txt', 'w')
try:
    f.write('Miscellaneous text')  # Not so misc anymore, huh?
finally:
    f.close()
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