Avoiding Excess Characters When Writing Files in Python

Feb 3, 2024 ยท 2 min read

When writing data to files in Python, it's important to be aware of any extra characters that may inadvertently be added to your output. This can cause errors or unexpected behavior if you later try to read and process the file contents.

The Main Culprits

The most common sources of extra characters when writing files in Python are:

  • Newline characters (\n) automatically added by print statements
  • Empty space padding from string formatting and concatenation operations
  • For example:

    name = "John"
    age = 30
    file.write(name + " " + str(age) + "\n")  

    This will write John 30\n to the file, including a new line at the end.

    Similarly, using string formatting:

    msg = f"{name} is {age} years old\n"
    file.write(msg)

    Also adds a new line character.

    Best Practices

    To avoid these excess characters:

  • Use file.write() directly instead of print() for writing files
  • Manually add newlines only where explicitly needed
  • Use string formatting without trailing padding:
  • msg = f"{name} is {age} years old"
    file.write(f"{msg}\n")
  • Or concatenate strings cleanly:
  • data = name + " " + str(age)
    file.write(f"{data}\n") 

    Following these tips will prevent unexpected output in your files. The key is being intentional about when you want newlines or padding space added to your written data.

    Removing unneeded characters also makes files smaller and easier to process. So it's worth taking the extra time to write clean file output in your Python programs.

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