Python - Keyword Arguments

Python allows to pass function arguments in the form of keywords which are also called named arguments. Variables in the function definition are used as keywords. When the function is called, you can explicitly mention the name and its value.

Calling Function With Keyword Arguments

The following example demonstrates keyword arguments in Python. In the second function call, we have used keyword arguments.

# Function definition is here
def printinfo( name, age ):
   "This prints a passed info into this function"
   print ("Name: ", name)
   print ("Age ", age)
   return

# Now you can call printinfo function
# by positional arguments
printinfo ("Naveen", 29)

# by keyword arguments
printinfo(name="miki", age = 30)

It will produce the following output −

Name: Naveen
Age 29
Name: miki
Age 30

Order of Keyword Arguments

By default, the function assigns the values to arguments in the order of appearance. However, while using keyword arguments, it is not necessary to follow the order of formal arguments in function definition. Use of keyword arguments is optional. You can use mixed calling. You can pass values to some arguments without keywords, and for others with keyword.

Example

Let us try to understand with the help of following function definition −

def division(num, den):
   quotient = num/den
   print ("num:{} den:{} quotient:{}".format(num, den, quotient))

division(10,5)
division(5,10)

Since the values are assigned as per the position, the output is as follows −

num:10 den:5 quotient:2.0
num:5 den:10 quotient:0.5

Example

Instead of passing the values with positional arguments, let us call the function with keyword arguments −

def division(num, den):
   quotient = num/den
   print ("num:{} den:{} quotient:{}".format(num, den, quotient))
   
division(num=10, den=5)
division(den=5, num=10)

Unlike positional arguments, the order of keyword arguments does not matter. Hence, it will produce the following output −

num:10 den:5 quotient:2.0
num:10 den:5 quotient:2.0

However, the positional arguments must be before the keyword arguments while using mixed calling.

Example

Try to call the division() function with the keyword arguments as well as positional arguments.

def division(num, den):
   quotient = num/den
   print ("num:{} den:{} quotient:{}".format(num, den, quotient))

division(num = 5, 10)

As the Positional argument cannot appear after keyword arguments, Python raises the following error message −

    division(num=5, 10)
                      ^
SyntaxError: non-keyword arg after keyword arg