Pratik kamble: Created page with "{| border=1 | '''Time''' |'''Narration''' |- | 00:01 | Welcome to the spoken tutorial on '''Using Python Modules'''. |- |00:06 |In this tutorial, you will learn to- Exec..."

2019-06-10T10:13:18Z

Created page with "{| border=1 | '''Time''' |'''Narration''' |- | 00:01 | Welcome to the spoken tutorial on '''Using Python Modules'''. |- |00:06 |In this tutorial, you will learn to- Exec..."

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{| border=1
| '''Time'''
|'''Narration'''

|-
| 00:01
| Welcome to the spoken tutorial on '''Using Python Modules'''.

|-
|00:06
|In this tutorial, you will learn to-

Execute '''Python scripts''' from '''command line'''

Use '''import''' in '''scripts '''and

Import '''numpy '''and''' matplotlib.pyplot modules'''

|-
| 00:22
|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'''

|-
|00:40
|To practise this tutorial, you should know how to

Use '''plot''' interactively

Embellish and save a '''plot'''

|-
|00:50
|If not, see the relevant '''Python''' tutorials on this website.

|-
| 00:55
| First we will learn what is a '''module'''.

|-
| 00:58
| A '''module''' is a file containing '''Python definitions''' and '''statements'''.

|-
| 01:04
|'''Modules''' are used to break down large programs into small manageable and organized files.

|-
| 01:12
| '''Definitions''' from a '''module''' can be '''imported''' into other '''modules''' or to the '''main module'''.

|-
|01:19
|Now let us see how to run a '''Python script''' from '''command line'''.

|-
| 01:24
| Open any '''text editor''' and type, '''print''''' inside brackets inside double quotes '''''Hello World'''

|-
|01:33
| We have created a simple '''Python script''' to print '''Hello World'''.

|-
|01:38
|Save this '''script''' as '''hello.py''' in the current '''working directory'''.

|-
|01:44
|Now let us open the '''terminal.'''

Then navigate to the '''directory''' where '''hello.py''' is saved.

|-
| 01:52
| Now type, '''python3 hello.py''' and press '''Enter'''.
It executes the '''script''' and gives the output as '''Hello World.'''

|-
| 02:04
| From here onwards, remember to press the '''Enter''' key after typing every '''command''' on the '''terminal'''.

|-
| 02:11
| Next we will see how to '''import modules''' and use them in '''Python scripts.'''

|-
| 02:17
|Let me open the file''' four''''' underscore '''''plot.py''' in the '''text editor.'''

|-
|02:23
|This file is available in the '''Code files '''link of this tutorial. You can download and use it.

|-
|02:31
| This '''code''' will '''plot''' for '''x, -x, sin of x '''and''' xsin of x'''

|-
|02:38
| When we '''run''' this '''code''', we will see the final '''plot''' as shown here.

|-
| 02:43
| Now let us '''run''' the file '''four '''''underscore''''' plot.py''' as a '''Python script'''.

|-
|02:49
| Type, '''python3''' '''four '''''underscore''''' plot.py'''

|-
| 02:55
|It gives an error '''linspace()''' is not defined.

|-
| 02:59
| It means that, '''function linspace()''' is not available in the current '''namespace'''.

|-
| 03:05
| A '''namespace''' is a system for making all the names in a program to be unique.

|-
|03:11
| Let us go back to the file''' four '''''underscore''''' plot.py.'''

|-
| 03:16
| Add this line as the first line in the '''script''', '''from numpy import '''''asterisk''

|-
|03:24
| When we use''' asterisk''' in '''imports, '''all the '''functions''' and '''constants''' are imported from '''numpy module'''.

|-
| 03:32
| '''linspace''' is a '''function''' available in '''numpy.'''

|-
| 03:36
| Press '''Ctrl + S''' to save the file.

|-
|03:40
| Now let us run the '''script''' again. Now it gave another '''NameError: name ‘plot’ is not defined.'''

|-
|03:49
| Let us edit the '''four '''''underscore''''' plot.py '''file''' '''again.

|-
|03:54
| Add the following as the second line in our '''script'''. '''from matplotlib.pyplot import *'''

|-
|04:04
| Now save the file.

|-
| 04:06
| '''plot''' is a '''function''' which is available in the '''matplotlib.pyplot. '''

|-
|04:12
|We will run the '''script''' again. We get the output now.

|-
|04:19
| We '''imported''' all the required '''modules''' using the '''keyword import'''.

|-
| 04:24
| Let me close this window.

|-
|04:28
| We can import only '''functions''' which are required from a '''module''' as, '''from numpy import linspace, pi, sin'''

|-
|04:37
| instead of, '''from numpy import *'''

|-
| 04:44
| In the same way we can import only required '''functions''' from '''matplotlib.pyplot'''
instead of, '''from matplotlib.pyplot import *'''

|-
| 04:59
| It is always good to use '''function''' names instead of '''asterisk'''.

|-
| 05:03
|If we use '''asterisk''' to '''import''' from a particular '''module,''' all the '''functions '''will be imported.

|-
| 05:11
|It replaces some existing '''functions''' with the same name in the '''namespace'''.

|-
| 05:17
| Now we will add only required '''functions''' from '''numpy''' and '''matplotlib.pyplot'''

|-
| 05:25
| Let us save the file.

|-
| 05:27
| We will run the code again in the '''terminal'''.

|-
|05:32
| Here, we got the '''plots '''for''' x, -x, sin of x '''and''' xsin of x''' in a single '''figure'''.

|-
|05:40
| In this method we '''imported''' all the required '''functions''' to the current '''namespace'''.

|-
| 05:46
| There is another way of fixing errors. Let us see that.

|-
| 05:51
| Open the file '''another''''' underscore '''''fix.py'''

|-
|05:56
| This file is also available in the '''Code files''' link of this tutorial.

|-
|06:01
| Notice that we are going to use the name '''plt''' instead of '''matplotlib.pyplot'''.''' '''

|-
|06:08
| '''plt '''is used as alias to the '''module matplotlib.pyplot'''

|-
|06:14
| Now, we use '''numpy.pi '''instead of just''' pi '''as we did in four'' underscore ''plot.py.

|-
|06:22
| '''Plot functions '''are called as

'''plt.plot()'''

'''plt.legend()'''

'''plt.annotate() '''

'''plt.xlim'''

'''plt.ylim'''

and '''plt.show()'''

|-
|06:43
| The advantage is that '''function''' names in '''imported modules''' do not get added to the current '''namespace'''.

|-
|06:51
| In order to use a '''function''' in an '''imported module''', we need to mention '''module-name.function-name'''

|-
|06:59
| Pause the video here.Try this exercise and then resume the video.

|-
|07:05
| Write a '''python script''' to '''plot''' a '''sine wave''' from''' -2pi '''to''' 2pi'''.

|-
|07:12
| Open the file '''sine.py''' for the solution. This file is also available in the '''Code files''' link. In the first line we '''import''' the required '''functions.'''

|-
|07:27
| The '''functions linspace, sin '''and''' constant pi''' are imported from the''' module numpy'''.

|-
|07:34
| We '''import''' the '''functions plot, legend, show, title, xlabel '''and''' ylabel '''from''' matplotlib.pyplot.'''

|-
|07:44
| And the rest of the '''code''' is to generate the '''plot'''.

|-
| 07:48
| Let us run the '''code''' and see the output.

|-
|07:52
| In the '''terminal''', type '''python3''' '''sine.py'''

|-
|07:58
| Now we can see our '''sine plot'''. Close the '''terminal'''.Let us move further in our topic.

|-
| 08:08
| We can run '''Python scripts''' in '''IPython interpreter '''also.

|-
|08:13
| Open another '''terminal''' and start the '''ipython interpreter''' by typing '''ipython3'''

|-
| 08:22
| Navigate to the '''directory''' where '''four '''''underscore''''' plot.py''' is saved and type ''percentage''''' run four '''''underscore''''' plot.py'''

|-
|08:35
| As before we can see the output with 4 '''plots'''.

|-
| 08:40
| '''Python''' has a very rich '''standard library''' of '''modules'''.

|-
|08:45
|Some of the '''standard modules''' are,

for''' Math: math, random '''

for''' Internet access: urllib2, smtplib'''

for''' System and Command line arguments: sys '''

|-
| 09:01
| Few more '''libraries'''

for''' Operating system interface: os '''

for''' regular expression: re '''

for''' compression: gzip, zipfile, tarfile '''

For more information refer to the below link.

|-
|09:20
|This brings us to the end of this tutorial. Let us summarize.

|-
|09:26
|In this tutorial, we have learnt to,

Run '''scripts''' from '''command line'''

'''Import modules''' by specifying the '''module''' name followed by an '''asterisk'''

|-
|09:38
|'''Import''' only the required '''functions''' from '''modules''' by specifying the '''function''' name

Use '''Python standard library'''.

|-
|09:47
|Here are some self assessment questions for you to solve

1. Which among the below is the most correct?

2. How the functions '''xlim() '''and '''ylim'''() can be imported to the current '''namespace'''?

|-
|10:02
|And the answers,

1. The option '''from matplotlib.pyplot import plot''' is the most correct one.

Because '''plot''' is a '''function''' of '''matplotlib.pyplot''' '''module'''.

|-
|10:18
| 2. Functions '''xlim'''() and '''ylim'''() can be '''imported''' to the current '''namespace''' as, '''from matplotlib.pyplot import xlim, ylim'''

|-
| 10:32
| Please post your timed queries in this forum.

|-
| 10:36
| Please post your general queries on Python in this forum.

|-
| 10:41
| FOSSEE team coordinates the TBC project.

|-
| 10:45
| Spoken Tutorial Project is funded by NMEICT, MHRD, Govt. of India.For more details, visit this website.

|-
| 10:56
| This is Priya from IIT Bombay signing off. Thanks for watching.

|}

Python-3.4.3/C4/Using-Python-Modules/English-timed - Revision history

Pratik kamble: Created page with "{| border=1 | '''Time''' |'''Narration''' |- | 00:01 | Welcome to the spoken tutorial on '''Using Python Modules'''. |- |00:06 |In this tutorial, you will learn to- Exec..."