Python - Functions - Azure Jupyter Notebooks

FUNCTIONS
ADRI JOVIN J J
ASSISTANT PROFESSOR (SR. GR.)
DEPARTMENT OF INFORMATIONTECHNOLOGY
SRI RAMAKRISHNA INSTITUTE OFTECHNOLOGY
Seven Days Faculty Development and Training Programme on
GE8151 - Problem Solving and
Python Programming

WHO’S A GREATTEACHER?
The mediocre teacher tells.
The good teacher explains.
The superior teacher demonstrates.
The great teacher inspires.
―William ArthurWard
31/05/2018 FUNCTIONS-PYTHON | 2

OBJECTIVE
Creating a simple function with a parameter
Exploring functions with return values
Creating functions with multiple parameters
Control Flow/Sequence in Python

EXPECTED LEARNING OUTCOMES
Create functions with a parameter
Create functions with a return value
Create functions with multiple parameters
Understand the control flow in Python
Cognitive level expected: “apply”

RECOMMENDEDTEACHING-AID
Jupyter Notebook - Open Source (requires Anaconda
environment)
http://notebooks.azure.com - Free cloud platform (requires
Microsoft account, probably a hotmail.com/live.com
account)
Spyder – Open Source (requires Anaconda environment)

LEARNING RESOURCES
 Official Python 3 Documentation - https://docs.python.org/3/library/index.html
 Dive Into Python - http://www.diveintopython3.net/
 Think Python - http://greenteapress.com/wp/think-python-2e/
 The Official PythonTutorial - https://docs.python.org/3/tutorial/
 Learn Python the HardWay - http://learnpythonthehardway.org/book/
 PEP 8 - https://www.python.org/dev/peps/pep-0008/
 PythonTutor - http://www.pythontutor.com/
 Reserved Keywords in Python -
https://docs.python.org/3.0/reference/lexical_analysis.html#id8 [Don’t use]

JUPYTER NOTEBOOK
http://notebooks.azure.com
Log-in with a Microsoft ID like
MSN/Hotmail/Live account
Easy to access from any where
24x7 availability
Easy transfer of notebooks

JUPYTER NOTEBOOK
 Create Libraries
 Clone Libraries
 Libraries may contain
number of Notebooks

JUPYTER NOTEBOOK
 Clone Libraries
number of Notebooks
 Jupyter Notebook format
(.ipynb files)

JUPYTER NOTEBOOK
 Creating a new Notebook
 Click + symbol > Name the
Notebook
Here, it is
“MY_FIRST_NOTEBOOK”
 Click “New”
Note: ItemType must be
selected or the file will be
blank

JUPYTER NOTEBOOK
 Code Cell
 Markdown Cell
 Raw NBConvert Cell
 Header Cell

RUNNING A CELL
Methods for running the code in a cell
 Click in the cell below and press "Ctrl+Enter" to run the code
or
 Click in the cell below and press "Shift+Enter" to run the code and move to the next cell
 Menu: Cell...
 > Run Cells runs the highlighted cell(s)
 > Run All Above runs the highlighted cell and above
 > Run All Below runs the highlighted cell and below

WORKING IN NOTEBOOK
EDIT MODE
 text cells in editing mode show markdown code
 Markdown cells keep editing mode appearance until the cell is run
 code (python 3) cells in editing look the same after editing, but may show different run output
 clicking another cell moves the green highlight that indicates which cell has active editing focus
CELLS NEEDTO BE SAVED
 the notebook will frequently auto save
 best practice is to manually save after editing a cell using "Ctrl + S" or alternatively, Menu: File > Save
and Checkpoint

ALTERING NOTEBOOK
ADD A CELL
 Highlight any cell and then... add a new cell using Menu: Insert > Insert Cell Below or Insert Cell Above
 Add with Keyboard Shortcut: "ESC + A" to insert above or "ESC + B" to insert below
CHOOSE CELLTYPE
 Format cells as Markdown or Code via the toolbar dropdown or Menu: Cell > CellType > Code or Markdown
 Cells default to Code when created but can be reformatted from code to Markdown and vice versa
CHANGE NOTEBOOK PAGE LANGUAGE
 The course uses Python 3 but Jupyter Notebooks can be in Python 2 or 3 (and a language called R)
 To change a notebook to Python 3 go to "Menu: Kernel > Change Kernel> Python 3"

FUNCTIONS WITH ARGUMENTS
Functions are used for code tasks that are intended to be reused
 Make code easier to develop and maintain
 Python allows
−User Defined Functions
−Built-in Functions (e.g.: print())

FUNCTIONS WITH ARGUMENTS
 print()can be called using arguments (or without) and sends text to
standard output, such as the console.
 print()uses parameters to define the variable arguments that can be
passed to the Function.
 print()defines multiple string/numbers parameters which means we
can send a long list of arguments to print(), separated by commas.

BASICS OF A USER DEFINED FUNCTION
 define a function with def
 use indentation (4 spaces)
 define parameters
 optional parameters
 return values (or none)
 function scope (basics defaults)
def some_function() :

CERTAIN RULES
 use a function name that starts with a letter or underscore (usually a
lower-case letter)
 function names can contain letters, numbers or underscores
 parenthesis () follow the function name
 a colon : follows the parenthesis
 the code for the function is indented under the function definition
(use 4 spaces for this course)

SYNTAX
def some_function():
#code the function tasks indented here
The end of the function is denoted by returning to no indentation

EXAMPLE
def say_hi():
print("Hello World!")
print("say hi!")
say_hi()
Output:
Hello World!
say hi!

CALLING FUNCTIONS
 Simple function can be called using the function name followed by
parentheses
print()
Example:
def say_hi():
print("say hi!")
say_hi()

TESTTHIS…
Test:
def say_hi():
print("say hi!")
def three_three():
print(33)
# calling the functions
say_hi()
print()
three_three()

TEST RESULT…
Output:
Hello World!
say hi!
33

TASK
Define and call a simple function shout()
shout() prints the phrase with "!" concatenated to the end
 takes no arguments
 indented function code does the following
 define a variable for called phrase and initialize with a short phrase
 prints phrase as all upper-case letters followed by "!"
 call shout at the bottom of the cell after the function def
(Tip: no indentation should be used)

FUNCTION WITH PARAMETERS
 print()and type()are examples of built-in functions that have
parameters defined
 type() has a parameter for a Python Object and sends back the
type of the object

ARGUMENTVS PARAMETER
 an argument is a value given for a parameter when calling a function
 type is called providing an Argument - in this case the string "Hello"
 Parameters are defined inside of the parenthesis as part of a
function def statement
 Parameters are typically copies of objects that are available for use
in function code
type(“Hello”)
def say_this(phrase):
print(phrase)

DEFAULT ARGUMENT
 Default Arguments are used if no argument is supplied
 Default arguments are assigned when creating the parameter list
def say_this(phrase = "Hi"):
print(phrase)
say_this()
say_this("Hello")
Hi
Hello
Hi Hello

TASK
Define shout_this()and call with variable argument
 define variable words_to_shout as a string gathered from user
input()
 Call shout_this() with words_to_shout as argument
 get user input()for the string words_to_shout
Hi Hello

FUNCTION WITH RETURNVALUE
type()returns an object type
type()can be called with a float the return value can be
stored in a variable
Hi Hello
object_type = type(2.33)

FUNCTION WITH RETURNVALUE
return keyword in a function returns a value after exiting
the function
Hi Hello
def msg_double(phrase):
double = phrase + " " + phrase
return double

TASK
Define function print_doctor() that takes a parameter
name
get user input for variable full_name
call the function using full_name as argument
print the return value
Hi Hello

FUNCTION WITH MULTIPLE PARAMETERS
Functions can have multiple parameters separated by
commas
Hi Hello
def make_schedule(period1, period2):
schedule = ("[1st] " + period1.title() + ", [2nd] " + period2.title())
return schedule
student_schedule = make_schedule("mathematics", "history")
print("SCHEDULE:", student_schedule)

TASK
Define make_schedule()adding a 3rd period to
 Start with the above example code
 add a parameter period_3
 update function code to add period_3 to the schedule
 call student_schedule()with an additional argument such as
'science'
 print the schedule
Hi Hello

SEQUENCE/FLOW OF EXECUTION
In programming, sequence refers to the order that code is
processed
Objects in Python, such as variables and functions, are not
available until they have been processed
Processing sequence flows from the top of a page of code to
the bottom
This often means that function definitions are placed at the
beginning of a page of code
Hi Hello

SEQUENCE/FLOW OF EXECUTION
Hi Hello
have_hat = hat_available('green')
print('hat available is', have_hat)
def hat_available(color):
hat_colors = 'black, red, blue,
green, white, grey, brown, pink'
return(color.lower() in
hat_colors)
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-1-95ed6a786fca> in <module>()
----> 1 have_hat = hat_available('green')
2 print('hat available is', have_hat)
3 def hat_available(color):
NameError: name 'hat_available' is not defined
In the statement have_hat = hat_available('green')the function
hat_available()needs to be called after the function has been defined
In the statement have_hat = hat_available('green') the function hat_available() needs to be called after the function has been defined

TASK
Change the Sequence to fix the NameError
Hi Hello
have_hat = hat_available('green')
print('hat available is', have_hat)
def hat_available(color):
hat_colors = 'black, red, blue, green, white, grey, brown, pink'
return(color.lower() in hat_colors)

TASK
Create and test market()
 market()takes 2 string arguments: commodity & price
 market returns a string in sentence form
 gather input for commodity_entry and price_entry to use in
calling market()
 print the return value of market()
Example of output: CommodityType: Basket costs Rs. 100/-
Hi Hello

TRAINING WORKBOOK
https://notebooks.azure.com/adrijovin/libraries/functions-
ge8151
Hi Hello
Disclaimer:
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Python is a registered trademark of the Python Software Foundation, USA
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Python - Functions - Azure Jupyter Notebooks

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