Python/C4/Writing-python-scripts/English-timed - Revision history

PoojaMoolya at 07:26, 27 March 2017

2017-03-27T07:26:20Z

PoojaMoolya at 10:43, 20 February 2017

2017-02-20T10:43:26Z

Gaurav at 10:32, 3 September 2014

2014-09-03T10:32:13Z

Gaurav at 10:31, 10 July 2014

2014-07-10T10:31:46Z

Gaurav at 10:28, 10 July 2014

2014-07-10T10:28:19Z

Gaurav at 10:27, 10 July 2014

2014-07-10T10:27:40Z

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Sneha at 05:36, 5 April 2013

2013-04-05T05:36:42Z

Sneha at 11:19, 19 March 2013

2013-03-19T11:19:05Z

Sneha at 10:51, 19 March 2013

2013-03-19T10:51:02Z

Minal: Created page with '{| border=1 !Visual Cue !Narration |- | 0:01 | Hello friends and welcome to the tutorial on "Writing Python scripts". |- | 0:05 | At the end of this tutorial, you will be able t…'

2013-01-02T12:16:20Z

Created page with '{| border=1 !Visual Cue !Narration |- | 0:01 | Hello friends and welcome to the tutorial on "Writing Python scripts". |- | 0:05 | At the end of this tutorial, you will be able t…'

New page

{| border=1
!Visual Cue
!Narration
|-
| 0:01
| Hello friends and welcome to the tutorial on "Writing Python scripts".

|-
| 0:05
| At the end of this tutorial, you will be able to,

# Understand what is importing.
# Write your own Python modules.
# Understand the <tt> __name__ == in double quotes __main__ underscore </tt> idiom

|-
| 0:19
| Before beginning this tutorial,we would suggest you to complete the tutorial on "Using Python modules".

|-
| 0:25
| Often we will have to reuse the code that we have written.

|-
| 0:29
| We do that by writing functions.

|-
| 0:31
| Functions are bundled into packages and are imported as and when required in other scripts.

|-
| 0:37
| Let us first write a function that computes the gcd of two numbers and save it in a script.

|-
| 0:44
| Open an editor and type the code.

|-
| 0:47
| Please take care of the indentation.

|-
|0:51
|So type in terminal gcd underscore script.py then type def gcd within bracket a comma b colon

while b colon
a comma b = b comma a percentage b

return a

|-
| 1:49
| We shall write a test function in the script that tests the gcd function every time the script is run.

|-
|1:56
|So type
if gcd within bracket 40 comma 12 == 4 colon
print within double quotes Everything OK
else colon
print within double quotes The GCD function is wrong

|-
| 2:53
| Let us save the file as script.py in <tt> slash home slash fossee slash gcd script.py</tt>

|-
| 3:05
| We shall run the script by typing in the terminal

|-
|3:11
|python slash home slash fossee slash gcd underscore script.py

|-
| 3:25
| We can see that the script is executed and everything is fine.

|-
| 3:29
| What if we want to use the gcd function in some of our other scripts.

|-
| 3:35
| This is also possible since every python file can be used as a module.

|-
| 3:39
| But first, we shall understand what happens when you import a module.

|-
|3:43
|So type ipython in terminal.

|-
| 3:52
| Open IPython and type import sys (hit enter)
sys.path

|-
| 4:15
| This is a list of locations where python searches for a module when it encounters an import statement.

|-
| 4:20
| Hence, when we just did <tt>import sys</tt>, python searches for a file named sys.py or a folder named sys in all these locations one by one, until it finds one.

|-
| 4:34
| We can place our script in any one of these locations and can import it.

|-
| 4:38
| The first item in the list is an empty string which means the current working directory is also searched.

|-
| 4:45
| Alternatively, we can also import the module if we are working in same directory where the script exists.

|-
|4:53
| Since we are in slash home slash fossee, we can simply do

|-
|4:59
|By typing on the terminal import gcd underscore script.py and hit enter.

|-
| 5:12
| We can see that the gcd underscore script is imported.

|-
| 5:18
| But the test code that we added at the end of the file is also executed.

|-
| 5:23
| But we want the test code to be executed only when the file is run as a python script or not when it is imported.

|-
| 5:30
| This is possible by using <tt> underscore underscore name underscore underscore </tt> variable.

|-
| 5:34
| First, we shall look at how to use the idiom and then understand how it works.

|-
| 5:41
| Go to the file and add this line as the beginning of the code and indent the code accordingly.

|-
|5:47
|So type if underscore underscore name underscore underscore == within double quotes underscore underscore main underscore underscore colon

|-
| 6:30
| Let us first run the code.

|-
|6:33
|So type in terminal python gcd underscore script.py

|-
|6:45
|We can see that

|-
|6:48
|There is an error coming up, its showing indentation error.

|-
|6:57
|So we have to edit the file and make indentation correct.

|-
| 7:20
| We can see that the test runs successfully.

|-
| 7:24
| Now we shall import the file gcd underscore script

|-
|7:29
|So type import gcd underscore script

|-
| 7:39
| We see that now the test code is not executed.

The <tt> underscore underscore name underscore underscore </tt> variable is local to every module and it is equal to <tt> underscore underscore main underscore underscore </tt> only when the file is run as a script.

|-
| 7:54
| Hence, all the code that goes in to the if block, <tt>if name == within double quotes main colon</tt> is executed only when the file is run as a python script.

|-
|8:08
| This brings us to the end of the tutorial.

|-
| 8:11
| In this tutorial, we have learnt to, 1. Know what happens when we import a module.

|-
| 8:16
| 2.Use a script as a module.

|-
| 8:18
| 3. Write test functions using the <tt> name </tt> idiom.

|-
|8:22
| Here are some self assessment questions for you to solve

|-
| 8:26
| 1. '''Which of the following variables contains the locations to search for'''<br/> python modules
** sys.pythonpath
** sys.path
** os.pythonpath
** os.path

|-
| 8:38
| 2. A module should contain only functions. - True - False

|-
| 8:43
| 3. The script <tt>utils.py</tt> is in one of locations of PYTHONPATH and contains the following code and the code is given.

|-
| 9:00
| And now look at the answers,

|-
| 9:04
| 1. <tt>sys.path</tt> contains the locations to search for python modules.

|-
| 9:10
| 2. False is the answer.

|-
| 9:13
| A module which contain a range of functions.

|-
| 9:19
| 3. After doing <tt>import utils</tt>, we can use the function <tt>show()</tt> as,

utils.show within bracket double quotes hey

|-
| 9:32
| So we hope you have enjoyed this tutorial and found it useful.

|-
| 9:35
| Thank you!

|}

@@ Line 209: / Line 209: @@
 |-
 | 08:26
-| '''Which of the following variables contains the locations to search for'''  python modules
+| Which of the following variables contains the locations to search for'''  python modules
-sys.pythonpath, sys.path, os.pythonpath, os.path
+sys.pythonpath, sys.path, os.pythonpath, os.path'''
 |-

@@ Line 113: / Line 113: @@
 |-
-|0 4:38
+|04:38
 | The first item in the list is an empty string which means the current working directory is also searched.
@@ Line 137: / Line 137: @@
 |-
-| 005:23
+| 05:23
 | But we want the test code to be executed only when the file is run as a python script or not when it is imported.
 |-
-| 5:30
+| 05:30
 | This is possible by using  underscore  underscore name underscore  underscore  variable.

@@ Line 66: / Line 66: @@
 |-
 | 2:53
-| Let us save the file as script.py in   slash home slash fossee slash gcd script.py</tt>
+| Let us save the file as script.py in   slash home slash fossee slash gcd script.py
 |-

@@ Line 12: / Line 12: @@
 # Understand what is importing.
 # Write your own Python modules.
-# Understand the   __name__ == in double quotes  __main__  underscore </tt> idiom
+# Understand the   __name__ == in double quotes  __main__  underscore   idiom
 |-

@@ Line 10: / Line 10: @@
 | 00:05
 | At the end of this tutorial, you will be able to,
 Understand what is importing.
-# Understand what is importing.
+Write your own Python modules.
-# Write your own Python modules.
+Understand the   __name__ == in double quotes  __main__  underscore   idiom
-# Understand the   __name__ == in double quotes  __main__  underscore   idiom
 |-
@@ Line 45: / Line 44: @@
 |-
 |00:51
-|So type in terminal gcd underscore script.py then type def gcd within bracket  a comma  b colon
+|So type in terminal gcd underscore script.py then type def gcd within bracket  a comma  b colon while b colon  a comma  b = b comma  a percentage b  return a
-−
- while b colon
   a comma  b = b comma  a percentage b
-−
-    return a
 |-
@@ Line 59: / Line 53: @@
 |01:56
 |So type
-if gcd within bracket 40 comma  12 == 4 colon
+if gcd within bracket 40 comma  12 == 4 colon, print  within double quotes Everything OK else colon  print  within double quotes The GCD function is wrong
-    print  within double quotes Everything OK
 else colon
-    print  within double quotes The GCD function is wrong
 |-
@@ Line 98: / Line 89: @@
 |-
 | 03:52
-| Open IPython and type import sys (hit enter)
+| Open IPython and type import sys (hit enter). sys.path
-                        sys.path
 |-
@@ Line 191: / Line 181: @@
 |-
 | 07:39
-| We see that now the test code is not executed.
+| We see that now the test code is not executed.The  underscore   underscore name underscore   underscore   variable is local to every module and it is equal to   underscore   underscore main underscore   underscore   only when the file is run as a script.
-−
 The  underscore   underscore name underscore   underscore   variable is local to every module and it is equal to   underscore   underscore main underscore   underscore   only when the file is run as a script.
 |-
@@ Line 221: / Line 209: @@
 |-
 | 08:26
-| 1. '''Which of the following variables contains the locations to search for'''  python modules
+| '''Which of the following variables contains the locations to search for'''  python modules
-** sys.pythonpath
+sys.pythonpath, sys.path, os.pythonpath, os.path
-** sys.path
-** os.pythonpath
-** os.path
 |-
 | 08:38
-| 2. A module should contain only functions. - True - False
+| A module should contain only functions. - True - False
 |-
 | 08:43
-| 3. The script  utils.py  is in one of locations of PYTHONPATH and contains the following code and the code is given.
+| The script  utils.py  is in one of locations of PYTHONPATH and contains the following code and the code is given.
 |-
@@ Line 241: / Line 226: @@
 |-
 |09:04
-| 1.  sys.path  contains the locations to search for python modules.
+| sys.path  contains the locations to search for python modules.
 |-
 | 09:10
-| 2. False is the answer.
+| False is the answer.
 |-
@@ Line 253: / Line 238: @@
 |-
 | 09:19
-| 3. After doing  import utils , we can use the function  show()  as,
+| After doing  import utils , we can use the function  show()  as, utils.show within bracket double quotes hey
-−
- utils.show within bracket double quotes hey
 |-

@@ Line 89: / Line 89: @@
 |-
-|0 3:39
+|03:39
 | But first, we shall understand what happens when you import a module.

@@ Line 1: / Line 1: @@
 {| border=1
-!Visual Cue
+|'''Time'''
-!Narration
+|'''Narration'''
 |-
 | 00:01

@@ Line 12: / Line 12: @@
 # Understand what is importing.
 # Write your own Python modules.
-# Understand the <tt> __name__ == in double quotes  __main__  underscore </tt> idiom
+# Understand the   __name__ == in double quotes  __main__  underscore </tt> idiom
 |-
@@ Line 66: / Line 66: @@
 |-
 | 2:53
-| Let us save the file as script.py in <tt> slash home slash fossee slash gcd script.py</tt>
+| Let us save the file as script.py in   slash home slash fossee slash gcd script.py</tt>
 |-
@@ Line 107: / Line 107: @@
 |-
 | 4:20
-| Hence, when we just did <tt>import sys</tt>, python searches for a file named sys.py or a folder named sys in all these locations one by one, until it finds one.
+| Hence, when we just did  import sys , python searches for a file named sys.py or a folder named sys in all these locations one by one, until it finds one.
 |-
@@ Line 143: / Line 143: @@
 |-
 | 5:30
-| This is possible by using <tt> underscore  underscore name underscore  underscore </tt> variable.
+| This is possible by using  underscore  underscore name underscore  underscore  variable.
 |-
@@ Line 193: / Line 193: @@
 | We see that now the test code is not executed.
-The <tt> underscore   underscore name underscore   underscore </tt> variable is local to every module and it is equal to <tt> underscore   underscore main underscore   underscore </tt> only when the file is run as a script.
+The  underscore   underscore name underscore   underscore   variable is local to every module and it is equal to   underscore   underscore main underscore   underscore   only when the file is run as a script.
 |-
 | 7:54
-| Hence, all the code that goes in to the if block, <tt>if name ==  within double quotes  main colon</tt> is executed only when the file is run as a python script.
+| Hence, all the code that goes in to the if block,  if name ==  within double quotes  main colon  is executed only when the file is run as a python script.
 |-
@@ Line 213: / Line 213: @@
 |-
 | 8:18
-| 3. Write test functions using the <tt> name </tt> idiom.
+| 3. Write test functions using the  name   idiom.
 |-
@@ Line 221: / Line 221: @@
 |-
 | 8:26
-| 1. '''Which of the following variables contains the locations to search for'''<br/> python modules
+| 1. '''Which of the following variables contains the locations to search for'''  python modules
 ** sys.pythonpath
 ** sys.path
@@ Line 233: / Line 233: @@
 |-
 | 8:43
-| 3. The script <tt>utils.py</tt> is in one of locations of PYTHONPATH and contains the following code and the code is given.
+| 3. The script  utils.py  is in one of locations of PYTHONPATH and contains the following code and the code is given.
 |-
@@ Line 241: / Line 241: @@
 |-
 | 9:04
-| 1. <tt>sys.path</tt> contains the locations to search for python modules.
+| 1.  sys.path  contains the locations to search for python modules.
 |-
@@ Line 253: / Line 253: @@
 |-
 | 9:19
-| 3. After doing <tt>import utils</tt>, we can use the function <tt>show()</tt> as,
+| 3. After doing  import utils , we can use the function  show()  as,
   utils.show within bracket double quotes hey