MyAI

Functions

Types:

• Built-in functions - print(), int() etc
• Functions defined in built-in modules
• User-defined functions

Type of Functional Arguments

• Positional or required arguments
• Keyword arguments
• Default arguments
• Positional-only arguments: can have ONLY positional arguments, or ONLY keyword arguments.
• Keyword-only arguments
• Arbitrary or variable-length arguments

Default Arguments

Default arguments in Python are the function arguments that will be used if no arguments are passed to the function call.

• In the below example, Python uses the default value for such an argument if no value is passed to it. If any value is passed, the default value is overridden with the actual value passed.

def printinfo( name, age = 35 ):
   print ("Name: ", name)
   print ("Age ", age)
   return

printinfo( age=50, name="miki" )
printinfo( name="miki" )

Keyword Arguments

Python allows to pass function arguments in the form of keywords which are also called named arguments.

def printinfo( name, age ):
   print ("Name: ", name)
   print ("Age ", age)
   return

printinfo( "Sunil", 30 ) # by positional arguments
printinfo( name="miki", age = 50 ) # by Keyword arguments

Keyword-Only Arguments

Keyword-only parameters indicate that arguments can only be passed to function by keywords. You can create keyword-only parameters using * symbol. All the parameters that come after * are strictly keyword-only parameters.

Ex: def func(a, b, *, c, d=40):

• In the example, c & d are keyword-only parameters as they follow * in the function definition. And a & b can be positional or keyword parameters. And d has default value of 40.

# Keyword only Arguments
print("---position only Arguments---")
def my_position(a, b, *, c, d=40):
    print('a =',a)
    print('b = ',b)
    print('c = ',c)
    print('d = ',d)
my_position(10, 20, c=30 )

Positional-only arguments

Positional-only parameters indicate that arguments can be passed to function only by position. You can create positional-only parameters using / symbol. All the parameters that come before / are strictly positional-only parameters.

Ex: def func(a, b, /, c, d=40):

• In the example, a & b are the positional-only parameters, c & d are positional or keyword. Also, d has a default value of 40.
• you can use func(10, 20, c=30) but you get type error if you pass func(a=10, b=20, c=30)

# position only Arguments
print("---position only Arguments---")
def my_position(a, b, /, c, d=40):
    print('a =',a)
    print('b = ',b)
    print('c = ',c)
    print('d = ',d)
my_position(10, 20, c=30 )
# You cannot pass my_position(a=10, 20, c=30) - SyntaxError: positional argument follows keyword argument

Arbitrary Arguments

• An argument prefixed with a single asterisk * for arbitrary positional arguments.
• An argument prefixed with two asterisks ** for arbitrary keyword arguments.

def add(*args):
   s=0
   for x in args:
      s=s+x
   return s
result = add(10,20,30,40)
print (result)

result = add(1,2,3)
print (result)

In the below example, The addr() function has an argument **kwargs which is able to accept any number of address elements like name, city, phno, pin, etc. Inside the function kwargs dictionary of kw:value pairs is traversed using items() method.

def addr(**kwargs):
   for k,v in kwargs.items():
      print ("{}:{}".format(k,v))

print ("pass two keyword args")
addr(Name="John", City="Mumbai")
print ("pass four keyword args")

# pass four keyword args
addr(Name="Raam", City="Mumbai", ph_no="9123134567", PIN="400001")

Recursion

Python also accepts function recursion, which means a defined function can call itself.

Functions example

Example

import os
print('Hello '+os.getlogin() + '! Executing python script')
print("\n")

def greetings( MyName ):
    print("Hello ",MyName)
    print('ID After passing: ',id(MyName))
    return

Name = 'Sunil'
print('ID Before passin: ',id(Name))
greetings(Name)

# Arbitrary Arguments, *args

print("---Arbitrary Arguments, *args---")
def kids(*name):
    print("2nd kid name is " + name[1])
kids("Child 1", "Child 2", "Child 3")

# Keyword Arguments

print("---Keyword arguments---")
def child_name(child1, child2, child3):
    print("Young child is", child3)
child_name(child1 = "Emil", child2 = "Tobias", child3 = "Linus")

# Arbitrary Keyword Arguments, **kwargs

print("---Arbitrary Keyword Arguments, **kwargs---")
def my_name(**name):
    print("My last name: ",name["lname"])
my_name(fname = "Sunil", lname = "Marella")

# Default Parameter Value
print("---Default Parameter Value---")
def my_country(country = "Netherlands"):
    print("I am living in ", country)
my_country("India")
my_country()

# position only Arguments
print("---position only Arguments---")
def my_position(x, /):
    print(x)
my_position(10)

print("my_position(x=10) - Type error")

# Keyword-Only Arguments

print("---Keyword only Arguments---")
def my_keyword(*, y):
    print(y)
my_keyword(y=5)

print("my_keyword(5) - Type error")

# Combine Positional-Only and Keyword-Only
print("---Combine Positional-Only and Keyword-Only---")
def my_comb_keyword(a, b, /, *, c, d):
  print(a + b + c + d)

my_comb_keyword(5, 6, c = 7, d = 8)

# Recursion

def tri_recursion(k):
  if(k > 0):
    result = k + tri_recursion(k - 1)
    print(result)
  else:
    result = 0
  return result

print("\n\nRecursion Example Results")
tri_recursion(6)

Result:

Hello sunil! Executing python script

ID Before passin:  139911559775536
Hello  Sunil
ID After passing:  139911559775536

---Arbitrary Arguments, *args---
2nd kid name is Child 2
---Keyword arguments---
Young child is Linus
---Arbitrary Keyword Arguments, **kwargs---
My last name:  Marella
---Default Parameter Value---
I am living in  India
I am living in  Netherlands
---position only Arguments---
10
my_position(x=10) - Type error
---Keyword only Arguments---
5
my_keyword(5) - Type error
---Combine Positional-Only and Keyword-Only---
26

Recursion Example Results
1
3
6
10
15
21

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