Type errors are one of the most common errors in Python. It occurs when an argument is passed to a function as a keyword argument that the function does not require. In simpler words, the error “unexpected keyword argument” is raised when you pass a parameter to a function which inherently doesn’t need an argument.
There are mainly three broad types of errors or exceptions in Python, and they are: syntax errors, logical errors and runtime errors. The most common errors are syntax errors such as type errors, attribute errors, etc.
Keywords are special words that are reserved for specific functions in Python. Keywords should not be used as variable names in programs. Keyword arguments or simply, arguments are specific words that are assigned specific values when we define functions.
Understanding Keyword and Positional Arguments in Python”
Keyword arguments are identifiable using specific names in functions, whereas positional arguments are specified based on their positions. In Python, positional arguments must precede keyword arguments or else they might raise a syntax error.
When you don’t know the number of keyword arguments that might be passed to a specific function, you can use two asterisks before the argument variable in the function definition. The most common convention is **kwargs which stands for “keyword arguments”, whereas for positional arguments, we use one asterisk before the variable name for varied number of positional arguments, such as, *args which stands for “arguments”.
Deciphering the ‘Unexpected Keyword Argument’ TypeError
The ‘unexpected keyword argument’ TypeError in Python arises when a function receives an argument it wasn’t designed to accept. This can be resolved by employing **kwargs to account for additional keyword arguments or by avoiding unnecessary arguments altogether.
This error is raised when a function call encounters an unwanted argument that was not specified when the function was initially defined by the programmer. For example, if a function is only allowed to parse positional arguments, but instead it identifies a keyword, it will raise a type error.
A type error is an exception that is raised when the type of operation performed on variables isn’t aligned with the operands’ type. In other words, when a function cannot comprehend the type of arguments passed when trying to execute its’ content. For example, if you pass two strings instead of integers in the math.prod() function, which returns the product of two numbers, it will raise a type error. Since, the type of argument specified doesn’t match with the intended variable type.
In the given example below, let’s define a function called calculate() which will calculate the factorial of a number given by the user. In this function, we only need one argument called num, which is going to be a user input and its’ factorial is computed. Now, if we pass a keyword argument in addition to the given number it will raise a type error. We’ll use the built in math module and the math.factorial(number) function.
import math #importing math module #defining the calculate function def calculate(num): #returning the result return math.factorial(num) #taking user input num=int(input("Enter required number= ")) #passing extra keyword argument ans=calculate(num,count=0) print("The answer is= ",ans)
The error would be raised as follows:
Enter required number= 4 --------------------------------------------------------------------------- TypeError Traceback (most recent call last) <ipython-input-1-4dfb15088f66> in <cell line: 9>() 7 num=int(input("Enter required number= ")) 8 #passing extra keyword argument ----> 9 ans=calculate(num,count=0) 10 print("The answer is= ",ans) TypeError: calculate() got an unexpected keyword argument 'count'
There are a couple of ways in which we can get rid of this error. Let’s look at them one by one.
Method 1: Utilizing **kwargs and *args to Resolve the TypeError
The easiest fix is to use two asterisks before defining keyword arguments or using one asterisk before assigning positional arguments. This helps in recognizing the varied number of arguments even when the programmer is unaware of the users necessities. It doesn’t matter how many arguments you try to pass, this fix will work for any number of parameters.
It is not necessary that all your variables will be named as kwargs or args, you can use any name you want except keywords. Also keep in mind that positional arguments should always precede keyword arguments, not vice versa.
Now, from the above example, let’s run the function again but this time, we’ll specify **kwargs , ceteris paribus. This will give you your desired output without raising any additional errors as shown below.
import math #importing math module #defining the calculate function but this time using **kwargs def calculate(num,**kwargs): #returning the result return math.factorial(num) #taking user input num=int(input("Enter required number= ")) #passing extra keyword argument ans=calculate(num,count=0) print("The answer is= ",ans)
The output would be:
Enter required number= 4 The answer is= 24
Method 2: Avoiding Unnecessary Arguments for Cleaner Code
When you specify parameters in functions, they are just memory locations that are allotted for future use in the form of variables available to the users. Using unnecessary arguments slows down the computing time of a program and makes your code heavy.
Avoid using keyword and positional arguments where it isn’t absolutely necessary. When not used properly they create unwanted problems nd raise exceptions and also slows down the flow of a program. We already know that Python, being an interpreted language has a speed disadvantage and using extra variables will lead to more time and speed compromise.
Wrapping Up: Proactively Managing ‘Unexpected Keyword Argument’ TypeErrors
In this article we have seen what type errors are in Python and how they can be solved. We have also gone through the reason behind such exceptions in code when trying to execute specific commands. Unnecessary arguments and parameters can raise these errors if not mentioned correctly. We have discussed in depth about the two ways in which we can get rid of these errors easily without breaking a sweat!
Having navigated the intricacies of Python’s TypeError and explored robust solutions, we can confidently tackle these common issues. Do you think the flexibility of **kwargs and *args is a strength or a weakness in Python’s design?