TypeError: expected str, bytes or os.PathLike object, not tuple

TypeError: expected str, bytes or os.PathLike object, not tuple #

The Python "TypeError: expected str, bytes or os.PathLike object, not tuple" occurs when we pass a tuple instead of a string when opening a file. To solve the error, use a for loop if you have to open multiple files or use the addition operator to get a filename from multiple strings.

Here is an example of how the error occurs.

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# 👇️ tuple
filenames = 'example-1.txt', 'example-2.txt'

# ⛔️ TypeError: expected str, bytes or os.PathLike object, not tuple
with open(filenames, 'r', encoding='utf-8') as f:
    lines = f.readlines()

    for line in lines:
        print(line)

The open() function expects a string for its first argument but we passed it a tuple.

If you have to open multiple files, use a for loop.

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# 👇️ tuple
filenames = 'example-1.txt', 'example-2.txt'

for filename in filenames:
    with open(filename, 'r', encoding='utf-8') as f:
        lines = f.readlines()

        for line in lines:
            print(line)

We used a for loop to iterate over the tuple and passed each filename to the open() function.

Notice that we are passing a string for the filename and not a tuple.

You might also get the error when trying to concatenate multiple strings to get the filename.

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# 👇️ tuple
filename = 'example', '.txt'

# ⛔️ TypeError: expected str, bytes or os.PathLike object, not tuple
with open(filename, 'r', encoding='utf-8') as f:
    lines = f.readlines()

    for line in lines:
        print(line)

The code sample creates a tuple by mistake.

One way to concatenate strings is to use the addition (+) operator.

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# 👇️ this is a string
filename = 'example' + '.txt'

with open(filename, 'r', encoding='utf-8') as f:
    lines = f.readlines()

    for line in lines:
        print(line)

The addition (+) operator can be used to concatenate strings.

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print('a' + 'b' + 'c')  # 👉️ 'abc'

Alternatively, you can use a formatted string literal.

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name = 'example'
ext = 'txt'

filename = f'{name}.{ext}'

with open(filename, 'r', encoding='utf-8') as f:
    lines = f.readlines()

    for line in lines:
        print(line)

Make sure to wrap expressions in curly braces - {expression}.

In case you declared a tuple by mistake, tuples are constructed in multiple ways:

• Using a pair of parentheses () creates an empty tuple
• Using a trailing comma - a, or (a,)
• Separating items with commas - a, b or (a, b)
• Using the tuple() constructor

If you aren't sure what type a variable stores, use the built-in type() class.

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my_tuple = 'example', '.txt'
print(type(my_tuple))  # 👉️ <class 'tuple'>
print(isinstance(my_tuple, tuple))  # 👉️ True

my_str = 'example.txt'
print(type(my_str))  # 👉️ <class 'str'>
print(isinstance(my_str, str))  # 👉️ True

The type class returns the type of an object.

The isinstance function returns True if the passed in object is an instance or a subclass of the passed in class.

Conclusion #

The Python "TypeError: expected str, bytes or os.PathLike object, not tuple" occurs when we pass a tuple instead of a string when opening a file. To solve the error, use a for loop if you have to open multiple files or use the addition operator to get a filename from multiple strings.