Python syntaxerror positional argument follows keyword argument

How to fix SyntaxError: positional argument follows keyword argument

When working with Python functions, you might encounter an error as follows:

This error usually occurs when you call a function that has both positional and named parameters.

In Python 2, the error message is slightly reworded as:

Both error messages give us hints on how to fix this error. This article explains the error in more detail and shows you how to fix it.

How this error happens

This error happens when you call a function and place an unnamed argument next to a named argument.

Let’s see an example that causes this error. Write a function named greet() with the following parameters:

   Next, call the function and pass the arguments as shown below:

The error complains that we placed a positional argument next to the keyword argument.

A keyword argument (also known as named argument) is a value that you pass into a function with an identifying keyword or name.

By contrast, a positional argument is an unnamed argument, and is identified by its position in the function call.

By default, Python arguments are positional arguments, and they must not be specified after keyword arguments when you call a function.

How to fix this error

To resolve this error, you need to make sure that you don’t pass any positional arguments after keyword arguments.

You need to pass another keyword argument after the keyword argument age= as follows:

You can use keyword arguments to pass arguments in a different order than the defined parameters.

All following examples could work:

Keyword arguments are optional, so you can also pass the same arguments without giving them names.

But you need to pass them in the same order as the parameters defined in the function:

Another thing that can cause this error is when you mistyped the keyword argument using the comparison == operator.

Pay close attention to the hobby argument below:

In this example, we intend to pass a keyword argument named hobby , but the comparison operator turns the named argument into an expression that returns either True or False .

When passing keyword arguments, make sure that you use the assignment = operator to avoid this error.

I hope this tutorial is helpful. Happy coding! 👍

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Как исправить: SyntaxError: позиционный аргумент следует за аргументом ключевого слова

Одна ошибка, с которой вы можете столкнуться в Python:

SyntaxError : positional argument follows keyword argument 

Эта ошибка возникает, когда вы используете позиционный аргумент в функции после использования аргумента ключевого слова .

Позиционные аргументы — это аргументы, перед которыми нет «ключевого слова».

Аргументы ключевых слов — это аргументы , перед которыми стоит «ключевое слово».

Если вы используете позиционный аргумент после аргумента ключевого слова, Python выдаст ошибку.

В следующем примере показано, как эта ошибка может возникнуть на практике.

Пример: Аргумент позиции следует за аргументом ключевого слова

Предположим, у нас есть следующая функция в Python, которая умножает два значения, а затем делит на третье:

def do_stuff (a, b): return a \* b / c 

В следующих примерах показаны допустимые и недопустимые способы использования этой функции:

Правильный способ №1: все позиционные аргументы

Следующий код показывает, как использовать нашу функцию со всеми позиционными аргументами:

Никакой ошибки не возникает, потому что Python точно знает, какие значения использовать для каждого аргумента в функции.

Верный способ № 2: все аргументы ключевых слов

Следующий код показывает, как использовать нашу функцию со всеми аргументами ключевого слова:

do_stuff(a= 4 , b= 10 , c= 5 ) 8.0 

И снова ошибка не возникает, потому что Python точно знает, какие значения использовать для каждого аргумента в функции.

Действенный способ № 3: позиционные аргументы перед ключевыми аргументами

Следующий код показывает, как использовать нашу функцию с позиционными аргументами, используемыми перед аргументами ключевого слова:

Никакой ошибки не возникает, потому что Python знает, что аргументу a должно быть присвоено значение 4 .

Неверный способ: позиционные аргументы после аргументов ключевого слова

Следующий код показывает, как мы можем попытаться использовать функцию с позиционными аргументами, используемыми после аргументов ключевого слова:

do_stuff(a= 4, 10, 5) SyntaxError : positional argument follows keyword argument

Возникает ошибка, потому что мы использовали позиционные аргументы после аргументов ключевого слова.

В частности, Python не знает, следует ли присваивать значения 10 и 5 аргументам b или c , поэтому он не может выполнить функцию.

Дополнительные ресурсы

В следующих руководствах объясняется, как исправить другие распространенные ошибки в Python:

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Python syntaxerror positional argument follows keyword argument

Last updated: Feb 17, 2023
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# SyntaxError: positional argument follows keyword argument

The Python «SyntaxError: positional argument follows keyword argument» occurs when we pass keyword arguments before positional ones in a call to a function.

To solve the error, pass positional arguments in the right order and pass any keyword arguments after the positional ones.

Here is an example of how the error occurs.

Copied! 
def get_employee(first, last, salary): return 'first': first, 'last': last, 'salary': salary> # ⛔️ SyntaxError: positional argument follows keyword argument get_employee('Bobby', last='Hadz', 100) 

Passing a positional argument to a function looks like ‘Bobby’, , whereas passing a keyword argument to a function looks like last=’Hadz’ .

• when passing a positional argument to a function, only the value is passed, e.g. ‘Bobby’ .
• when passing a keyword argument to a function, the name of the argument and the corresponding value are passed, e.g. first = ‘Bobby’ .

The error was caused because we passed a keyword argument last , and then provided a value for the salary positional argument.

If you specify keyword arguments before positional ones, Python has no way of knowing a value for which positional argument is provided.

Instead, the keyword arguments must come after the positional ones.

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def get_employee(first, last, salary): return 'first': first, 'last': last, 'salary': salary> # ✅ keyword arguments come after positional ones result = get_employee('Bobby', last='Hadz', salary=100) # 👇️ print(result) 

We passed first as a positional argument and last and salary as keyword arguments to resolve the issue.

# Only passing positional arguments to the function

One way to solve the error is to only pass positional arguments to the function.

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def get_employee(first, last, salary): return 'first': first, 'last': last, 'salary': salary> # ✅ only passing positional arguments to the function result = get_employee('Bobby', 'Hadz', 100) print(result) # 👉️ 

The example above only uses positional arguments. The function knows for which parameter we passed a value based on the order of the positional arguments.

# Only passing keyword arguments to the function

Alternatively, you can only pass keyword arguments to the function.

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def get_employee(first, last, salary): return 'first': first, 'last': last, 'salary': salary> result = get_employee(salary=100, first='Alice', last='Smith') print(result) # 👉️ 

We only passed keyword arguments in the function call. Python knows for which parameter we passed a value based on the name of the keyword argument, e.g. salary=100 .

# Passing positional and keyword arguments to the function

You can also pass positional and keyword arguments in the same function call. Note that keyword arguments must follow positional ones.

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def get_employee(first, last, salary): return 'first': first, 'last': last, 'salary': salary> result = get_employee('Bobby', salary=100, last='Hadz') print(result) # 👉️ 

We used a positional argument ( Bobby ) and 2 keyword arguments — ( salary=100 and last=’Hadz’ ).

Make sure that any positional arguments you specify in the function call are passed in the correct order (the order must correspond to the parameter list in the function’s definition).

The order you pass the keyword arguments in doesn’t matter, as long as they come after the positional ones.

# The order of the positional arguments matters

Make sure that you aren’t just blindly moving the keyword arguments after all of the positional ones because the order of the positional arguments matters.

Here is an example of how this can go wrong.

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def get_employee(first, last, salary): return 'first': first, 'last': last, 'salary': salary> # ⛔️ TypeError: get_employee() got multiple values for argument 'last' result = get_employee('Bobby', 100, last='Hadz') 

The keyword argument in the example comes after any positional ones, but we still got an error.

The reason we got the error is that we used positional arguments to pass a value for the first and last parameters and then passed a value for the last parameter using a keyword argument.

The easiest way to solve the error in the example is to pass only positional arguments (in the correct order) to the function.

Copied! 
def get_employee(first, last, salary): return 'first': first, 'last': last, 'salary': salary> # ✅ only passing positional arguments (in the correct order) result = get_employee('Bobby', 'Hadz', 100) # 👇️ print(result) 

# The order of a Python function’s parameters

A function’s parameters must be defined in the following order:

1. Positional parameters (required, non-default).
2. Default parameters or keyword arguments.
3. *args — receives excess positional arguments.
4. **kwargs — receives excess keyword arguments.

# Using *args and **kwrags in a function’s definition

You might also see the *args and **kwargs syntax being used to receive excess positional or keyword arguments in a function.

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def get_employee(first, salary, last='Doe', *args, **kwargs): print(args) # 👉️ ('developer', ) print(kwargs) # 👉️ return 'first': first, 'last': last, 'salary': salary> emp_1 = get_employee( 'Bobby', 100, 'Hadz', 'developer', country='Belgium' ) # 👇️ print(emp_1) 

The form *identifier is initialized to a tuple that receives any excess positional arguments.

The form **identifier is initialized to an ordered mapping that receives any excess keyword arguments.

An excess positional argument with the value of developer was supplied to the function, so it got added to the args tuple.

Similarly, the function doesn’t define a country argument, so it got added to the **kwargs dictionary.

We passed the value developer as a positional argument and the country=’Belgium’ value as a keyword argument.

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emp_1 = get_employee( 'Bobby', 100, 'Hadz', 'developer', country='Belgium' ) 

Note that the keyword argument comes after all positional ones.

You can also only use **kwargs or *args , depending on your use case.

# Only taking excess keyword arguments

Here is an example function that only takes excess keyword arguments.

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def get_employee(first, salary, last='Doe', **kwargs): # 👇️ print(kwargs) return 'first': first, 'last': last, 'salary': salary> emp_1 = get_employee( 'Bobby', 100, country='Belgium', city='Example' ) # 👇️ print(emp_1) 

The function doesn’t define the country and city arguments, so they got added to the kwargs dictionary.

# Define default parameters after positional ones

The same is the case when a function definition has default parameters — it has to define its default parameters after the positional ones.

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# 👇️ default parameter `last='Doe'` def get_employee(first, salary, last='Doe'): return 'first': first, 'last': last, 'salary': salary> # 👇️ not passing value for default parameter emp_1 = get_employee('Bobby', 100) print(emp_1) # # 👇️ passing value for default parameter emp_2 = get_employee('Alice', 100, 'Smith') print(emp_2) # 

Default parameter values have the form parameter = expression .

When we declare a function with one or more default parameter values, the corresponding arguments can be omitted when the function is invoked.

Positional parameters cannot follow a parameter with a default value because otherwise, Python has no way of knowing if we passed an argument for the default parameter or for a positional one.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

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