Nirmala Venkat at 07:38, 24 October 2018

2018-10-24T07:38:21Z

Nancyvarkey at 03:09, 23 October 2018

2018-10-23T03:09:05Z

Priyacst: Created page with "'''Title of script''': '''Writing Python scripts ''' '''Author: Aditya Palaparthy, Arun KP''' '''Keywords: Python, Ipython, python script, import module, name variable, vide..."

2018-10-09T11:20:19Z

Created page with "'''Title of script''': '''Writing Python scripts ''' '''Author: Aditya Palaparthy, Arun KP''' '''Keywords: Python, Ipython, python script, import module, name variable, vide..."

New page

'''Title of script''': '''Writing Python scripts '''

'''Author: Aditya Palaparthy, Arun KP'''

'''Keywords: Python, Ipython, python script, import module, name variable, video tutorial'''

{| style="border-spacing:0;"
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| <center>'''Visual Cue'''</center>
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| <center>'''Narration'''</center>

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Show Slide title
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Welcome to the spoken tutorial on '''Writing Python scripts'''.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Show Slide

Objectives

| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| In this tutorial we will learn,

* What is importing
* Write your own Python modules and
* Understand the ''double underscore '''''name''' ''double underscore double equal to within double quotes'' ''double underscore '''''main ''double underscore '''''idiom

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Show Slide

System Specifications
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| To record this tutorial, I am using

* '''Ubuntu Linux 16.04''' operating system
* '''Python 3.4.3'''
* '''IPython 5.1.0''' and
* '''Gedit text editor'''

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Show Slide

Prerequisite slide
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| To practise this tutorial, you should know how to

* run basic '''Python '''commands on the '''IPython console '''and
* use''' python modules.'''

If not, see the relevant '''Python '''tutorials on this website.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Show Slide

Python Modules

| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| We can write '''Python modules''' to bundle functions.

We can then make use of these '''functions''' by importing '''modules''' to other '''scripts.'''

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"|
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Let us first write a function and save it in a script.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Open an editor and type the following code

'''def gcd(a, b):'''

'''while b:'''

'''a, b = b, a%b'''

'''return a'''

'''if gcd(40, 12) == 4:'''

'''print ("Everything is OK")'''

'''else:'''

'''print ("The GCD function is wrong")'''
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Open any text editor and type the below code.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Highlight '''def gcd(a, b):'''

'''while b:'''

'''a, b = b, a%b'''

'''return a'''

Highlight '''if gcd(40, 12) == 4:'''

'''print ("Everything is OK")'''

'''else:'''

'''print ("The GCD function is wrong")'''
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| This Python module has a function to compute '''gcd''' of two numbers.

Please take care of the indentation.

We have included a test case in the script.

This '''test case''' will check the '''gcd''' '''function''' every time the script is run.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Save the script as gcd_script.py

| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Let us save the file as '''gcd''''' underscore '''''script.py''' in''' '''the''' '''current working directory'''.'''

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Type

'''ipython3'''
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Open a new terminal.

Type,

'''ipython3''' and press''' Enter.'''

From here onwards remember to press the Enter key after typing every command on the terminal.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Type,

'''%run gcd_script.py'''

Highlight the output

“'''Everything is OK'''”
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Now we will run the script.

Type,

''percentage '''''run gcd '''''underscore''''' script.py'''

We get an output which says “'''Everything is OK'''”.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Switch to the gcd_script.py
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| It means that the test case checking '''gcd '''''inside brackets '''''40 '''''comma''''' 12 '''''equals to''''' 4 '''is passed.

What if we want to use the '''gcd''' '''function''' in some other '''scripts'''.

This is possible since every '''python''' file can be used as a '''module'''.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Type,

'''import sys'''

| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| But first, we will understand what happens when we '''import''' a '''module'''.

Type,

'''import sys'''

|-
| style="background-color:#ffffff;border-top:none;border-bottom:0.5pt solid #000001;border-left:0.5pt solid #000001;border-right:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Type, '''sys.path'''
| style="background-color:#ffffff;border-top:none;border-bottom:0.5pt solid #000001;border-left:0.5pt solid #000001;border-right:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Now type '''sys.path'''

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Highlight the output

Highlight the empty string

| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| We can see a list of locations.

This indicates that python searches for a module when it encounters an '''import''' statement.

The standard modules are built into python itself.

Otherwise it is found in system locations like ''slash '''''usr '''''slash '''''lib '''''slash '''''python3.4 '''''slash ''

The first item in the '''list''' is an empty '''string.'''

It means the '''current working directory''' is also searched.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Type,

'''import gcd_script'''

Highlight '''Everything is OK'''

Type,

'''print("gcd of 187 and 391 is", gcd_script.gcd(187, 391))'''

Highlight '''gcd of 187 and 391 is 17'''
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| We can '''import''' a module present in the '''current working directory.'''

Type,

'''import gcd '''''underscore''''' script'''

Since '''gcd '''''underscore''''' script.py '''is in the '''current working directory''', import will work directly.

Type the '''print''' statement as shown here.

We get the gcd of 187 and 391 as output, which is 17

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Highlight Everything is OK

| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| We can also see the output “'''Everything is OK'''” that we added as''' test code.'''

This is also executed when we imported '''gcd '''''underscore''''' script.'''

The test code is added to check the '''gcd''' function.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| '''Slide:'''

'''__name__ variable'''.

Highlight '''__name__'''
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Test code should only be executed when we '''run''' the python '''script''' independently.

To execute the test code when the module is imported to other scripts, we can use ''double underscore '''''name '''''double underscore '''''variable'''.

Hereafter I will call this as '''name''' variable.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Switch to '''gcd_script.py'''

Add '''if __name__ == "__main__":'''

after the line '''return a'''
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| First, we shall look at how to use the variable and then understand how it works.

Now we will add this variable in the script '''gcd '''''underscore''''' script.py'''

Type the following after '''return a''' statement,

'''if '''''double underscore '''''name '''''double underscore double equal to inside double quotes double underscore '''''main '''''double underscore colon''

Indent the code properly.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Save the file
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Save the file.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Type

'''%run''' '''gcd_script.py'''

Highlight

'''Everything is OK'''
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Let us run the code.

Type,

''percentage '''''run''' '''gcd '''''underscore''''' script.py'''

We can see that the test is executed successfully and we get output as '''Everything is OK'''

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Type, '''import gcd_script'''

Type,

'''exit'''
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Now we will check the changes by importing the module.

We didn’t see any changes.

Note that, once a module is imported, it cannot be imported again in an existing '''IPython console. '''

So we will exit the existing '''IPython console''' by typing '''exit.'''

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Open terminal and type '''ipython3'''
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Open another terminal. Type '''ipython3'''.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Type

'''import gcd_script'''
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Now we will import '''gcd '''''underscore''''' script.py.'''

Type,

'''import gcd '''''underscore''''' script'''

We can see that now the test code is not executed.

'''Everything is OK''' is not displayed as output.''' '''

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Open '''gcd_script.py '''and highlight the if __name__ == "__main__":

block in the file '''gcd_script.py'''
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| The '''name variable''' is local to every '''module'''.

It is equal to''' main''' only when the file is run as a script.

Hence, all the code under the block, '''if name '''''double equal to within double quotes''''' main '''is executed only when the file is run as a '''python''' '''script'''.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Switch terminal
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Switch back to the terminal.

|-
| style="background-color:#ffffff;border-top:none;border-bottom:0.5pt solid #000001;border-left:0.5pt solid #000001;border-right:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Type,

'''from gcd_script import gcd'''

'''def check_relative_prime(a,b):'''

'''if gcd(a,b)==1:'''

'''print("Yes, %d and %d are relatively prime" %(a,b))'''

'''else:'''

'''print("No, %d and %d are not relatively prime" %(a,b))'''

'''check_relative_prime(11,3)'''

Highlight '''Yes, 11 and 3 are relatively prime'''
| style="background-color:#ffffff;border-top:none;border-bottom:0.5pt solid #000001;border-left:0.5pt solid #000001;border-right:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Type the following code which checks whether two numbers are relatively prime.

We have''' imported gcd function '''from''' gcd '''''underscore''''' script.'''

And use it in our calculations without the test code being executed.

Two numbers are relatively prime when their gcd is equal to one.

So we get output as '''Yes, 11 and 3 are relatively prime.'''

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Slide
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Every Python file can be run in two ways:

* As an independent stand-alone script or
* As a Python module which can be imported by other Python scripts or modules.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Show Slide

Summary slide

| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| This brings us to the end of this tutorial. Let us summarize.

In this tutorial, we have learnt to,''' '''

* Import a module
* Use a script as a module
* Write test condition using the name variable
* Restart IPython3 if a changed module is to be imported again.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Show Slide

Evaluation
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Here are some self assessment questions for you to solve

# Which of the following variables contains the locations to search for''' '''python modules
# A module should contain only one function. True or False

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Show Slide

Solutions

| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| And the answers,''' '''

# '''sys.path''' contains the locations to search for python modules.
# '''False'''. A module can contain a wide range of functions.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Show Slide Forum
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Please post your timed queries in this forum.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Show Slide Fossee Forum
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Please post your general queries on Python in this forum.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Slide Textbook Companion
| style="background-color:#ffffff;border:0.5pt solid #000001;padding:0.106cm;"| FOSSEE team coordinates the TBC project.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Show Slide

Acknowledgement
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Spoken Tutorial Project is funded by NMEICT, MHRD, Govt. of India.

For more details, visit this website.

|-
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| Show Slide Thank You
| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"| This is Priya from IIT Bombay signing off. Thanks for watching.

|}

← Older revision		Revision as of 07:38, 24 October 2018
Line 322:		Line 322:
	\| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"\| Now we will check the changes by '''importing''' the '''module'''.		\| style="background-color:#ffffff;border:0.5pt solid #000001;padding-top:0cm;padding-bottom:0cm;padding-left:0.097cm;padding-right:0.191cm;"\| Now we will check the changes by '''importing''' the '''module'''.

		+	Type,'''import gcd_script'''

	We didn’t see any changes.		We didn’t see any changes.

Python-3.4.3/C4/Writing-Python-Scripts/English - Revision history

Nirmala Venkat at 07:38, 24 October 2018

Nancyvarkey at 03:09, 23 October 2018

Priyacst: Created page with "'''Title of script''': '''Writing Python scripts ''' '''Author: Aditya Palaparthy, Arun KP''' '''Keywords: Python, Ipython, python script, import module, name variable, vide..."