Defining functions

Beginning Python Programming

Makzan, 2020 April.

Defining functions

  • Functions usage
  • Functions parameters
  • Returning result
  • lambda function

Code example

# Defining functions
def square(x):
  return x*x

# Using the function
print( square(2) )
print( square(5) )
print( square(10) )

Take a deep look of function

# Defining functions
def square(x):
    return x*x

1. "def" function

2. function name

3. parameters

4. colon (:)

5. indentation

6. return

7. result

Parameters example

def percent(x, y=100):
    return x / y * 100

print( percent(3,10))
# 30.0

print( percent(1,3))
# 33.3333333333

print( round(percent(1,3), 2))
# 33.33

print( percent(y=10,x=2))
# 20.0

print( percent(30))
#30.0
def percent(x, y=100):
    return x / y * 100

print( percent(3,10))
# 30.0

print( percent(1,3))
# 33.3333333333

print( round(percent(1,3), 2))
# 33.33

print( percent(y=10,x=2))
# 20.0

print( percent(30))
#30.0

Parameters example

def percent(x, y=100):
    return x / y * 100

print( percent(3,10))
# 30.0

print( percent(1,3))
# 33.3333333333

print( round(percent(1,3), 2))
# 33.33

print( percent(y=10,x=2))
# 20.0

print( percent(30))
#30.0

Parameters example

def percent(x, y=100):
    return x / y * 100

print( percent(3,10))
# 30.0

print( percent(1,3))
# 33.3333333333

print( round(percent(1,3), 2))
# 33.33

print( percent(y=10,x=2))
# 20.0

print( percent(30))
#30.0

Parameters example

def percent(x, y=100):
    return x / y * 100

print( percent(3,10))
# 30.0

print( percent(1,3))
# 33.3333333333

print( round(percent(1,3), 2))
# 33.33

print( percent(y=10,x=2))
# 20.0

print( percent(30))
#30.0

Parameters example

def percent(x, y=100):
    return x / y * 100

print( percent(3,10))
# 30.0

print( percent(1,3))
# 33.3333333333

print( round(percent(1,3), 2))
# 33.33

print( percent(y=10,x=2))
# 20.0

print( percent(30))
#30.0

Parameters example

lambda x: x*x

Lambda function

A one-line function without function name.

quare = lambda x: x*x
print(square(10))

Lambda function

In rare case, we give lambda function a name

L = list(range(1,10))
print(L) 
# [1,2,3,4,5,6,7,8,9]

# We can transform the list
L2 = list( map(lambda x: x*x, L) )
print(L2) 
# [1, 4, 9, 16, 25, 36, 49, 64, 81]

Lambda function

Better usage, when we need an adhoc one-line function.