Difference between revisions of "Python-3.4.3/C2/Using-plot-command-interactively/English-timed"

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|-
 
|-
 
| 00:01
 
| 00:01
−
| Hello friends. Welcome to the tutorial on using '''plot '''command interactively in '''IPython'''
+
| Hello friends! Welcome to the tutorial on using '''plot '''command interactively in '''IPython'''.
  
 
|-
 
|-
 
| 00:08
 
| 00:08
−
|At the end of this tutorial, you will be able to,
+
|At the end of this tutorial, you will be able to:
  
−
Create simple '''plots''' of '''mathematical''' '''functions'''.
+
create simple '''plots''' of mathematical '''functions''',
  
−
Use the '''Plot''' '''window''' to study '''plots '''better.
+
use the '''Plot window''' to study '''plots '''better.
  
 
|-
 
|-
 
| 00:20
 
| 00:20
−
| To record this tutorial, I am using  
+
| To record this tutorial, I am using:
  
−
'''Ubuntu Linux 14.04''' operating system
+
'''Ubuntu Linux 14.04''' operating system,
  
−
'''Python 3.4.3'''
+
'''Python 3.4.3''' and
  
 
'''IPython 5.1.0'''
 
'''IPython 5.1.0'''
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|Pre-requisites to practise this tutorial are -
 
|Pre-requisites to practise this tutorial are -
  
−
You should know how to run basic '''Python '''commands on the '''ipython console.'''
+
you should know how to '''run''' basic '''Python '''commands on the '''ipython console.'''
  
 
|-
 
|-
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|-
 
|-
 
| 01:05
 
| 01:05
−
| Let us initialise the '''pylab package'''. Type '''percentage''' '''pylab '''and press''' Enter'''
+
| Let us initialise the '''pylab package'''. Type: percentage '''pylab '''and press''' Enter'''.
  
 
|-
 
|-
 
| 01:16
 
| 01:16
−
| Let's first understand what is '''Pylab'''
+
| Let's first understand what is '''Pylab'''.
  
 
|-
 
|-
 
| 01:20
 
| 01:20
−
|'''Pylab''' is a convenient '''Python''' '''module''' -
+
|'''Pylab''' is a convenient '''Python''' '''module'''  
−
 
+
which provides-
−
which provides '''plotting''' functionality and has '''mathematical''' and '''scientific''' '''functions'''.  
+
'''plotting''' functionality and  
 +
has mathematical and scientific '''functions'''.  
  
 
|-
 
|-
 
| 01:32
 
| 01:32
−
| After running '''percentage pylab '''in the i'''Python console''' you will see a message-
+
| After running '''percentage pylab '''in the '''iPython console''', you will see a message-
  
 
“'''Using matplotlib backend: TkAgg ”.'''
 
“'''Using matplotlib backend: TkAgg ”.'''
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|-
 
|-
 
|01:45
 
|01:45
−
| But sometimes you may get an error that says  
+
| But sometimes you may get an error that says-
 
'''“ImportError: No module named matplotlib”.'''
 
'''“ImportError: No module named matplotlib”.'''
  
 
|-
 
|-
 
|01:55
 
|01:55
−
| In such cases, you have to install '''matplotlib''' and run this '''command''' again.
+
| In such cases, you have to install '''matplotlib''' and '''run''' this '''command''' again.
  
 
|-
 
|-
 
|02:02  
 
|02:02  
−
| Let's come back to the '''ipython console'''. Type ''''linspace'''' followed by a question mark in '''ipython console. ''' Press '''Enter'''
+
| Let's come back to the '''ipython console'''. Type ''''linspace'''' followed by a question mark in '''ipython console. ''' Press '''Enter'''.
  
 
|-
 
|-
 
|02:14
 
|02:14
−
| Please note that the '''command '''is''' linspace '''and''' '''not''' linespace.'''
+
| Please note that the '''command '''is''' linspace '''and not''' linespace.'''
  
 
|-
 
|-
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| The displayed information says that
 
| The displayed information says that
  
−
'''linspace''' returns evenly spaced '''numbers''',
+
'''linspace''' returns evenly spaced numbers  
 
which are calculated over the interval '''start''' and '''stop'''.  
 
which are calculated over the interval '''start''' and '''stop'''.  
  
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|-
 
|-
 
|02:41
 
|02:41
−
| Let's try to generate 100 points from 1 to 100. Type '''linspace brackets 1 comma 100 comma 100'''  
+
| Let's try to generate 100 points from 1 to 100. Type: '''linspace brackets 1 comma 100 comma 100'''  
  
 
|-
 
|-
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|-
 
|-
 
|03:21
 
|03:21
−
| We do that by typing '''linspace brackets 0 comma 1 comma 200 '''and press enter.  
+
| We do that by typing '''linspace brackets 0 comma 1 comma 200 '''and press '''Enter'''.  
  
 
|-
 
|-
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|-
 
|-
 
| 03:40
 
| 03:40
−
| In '''linspace,''' the '''start''' and '''stop''' points can be '''integers''', '''decimals''', or '''constants'''.  
+
| In '''linspace,''' the '''start''' and '''stop''' points can be integers, decimals or '''constants'''.  
  
 
|-
 
|-
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|-
 
|-
 
|03:58
 
|03:58
−
| So type '''linspace brackets minus pi comma pi comma 100 '''and''' '''press '''Enter'''.
+
| So, type: '''linspace brackets minus pi comma pi comma 100 '''and press '''Enter'''.
  
 
|-
 
|-
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|-
 
|-
 
|04:15  
 
|04:15  
−
| Now, let us save this to a variable, say '''t'''.  Press '''Enter'''.
+
| Now, let us '''save''' this to a variable, say '''t'''.  Press '''Enter'''.
  
 
|-
 
|-
 
| 04:22
 
| 04:22
−
| If we now type '''len bracket t '''and press '''Enter''', we will get the number of points between '''minus''' '''pi''' and '''pi.  
+
| If we now type: '''len bracket t '''and press '''Enter''', we will get the number of points between '''minus pi''' and '''pi'''.  
  
 
|-
 
|-
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|-
 
|-
 
| 04:37
 
| 04:37
−
| Next, let's try and plot a '''cosine''' '''curve''' between '''minus''' '''pi''' and''' pi.'''
+
| Next, let's try and plot a '''cosine''' curve between '''minus pi''' and''' pi.'''
  
 
|-
 
|-
 
|04:43
 
|04:43
−
| For this, we use the '''plot''' command. Type '''plot brackets t comma cos(t) '''and press '''Enter.'''
+
| For this, we use the '''plot''' command. Type: '''plot brackets t comma cos(t) '''and press '''Enter.'''
  
 
|-
 
|-
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|-
 
|-
 
|05:21
 
|05:21
−
| And then '''plot''' by typing '''plot(t comma cosine) '''and press '''Enter'''
+
| And then plot by typing '''plot(t comma cosine) '''and press '''Enter'''.
  
 
|-
 
|-
 
| 05:31
 
| 05:31
−
| To clear the '''plot''', we have to use the '''clf()''' function. This avoids overlapping of new '''plot'''s over older '''plots'''.
+
| To clear the '''plot''', we have to use the '''clf()''' function. This avoids overlapping of new plots over older plots.
  
 
|-
 
|-
 
| 05:42
 
| 05:42
−
| In the '''console''', type '''clf() '''and press '''Enter. '''The previous '''plot''' is cleared and a blank '''plot window''' is displayed.
+
| In the '''console''', type: '''clf() '''and press '''Enter. '''The previous '''plot''' is cleared and a blank '''plot window''' is displayed.
  
 
|-
 
|-
 
| 05:56
 
| 05:56
−
| Now, let's try to plot a '''sine''' '''plot'''.  
+
| Now, let's try to plot a '''sine''' plot.  
  
 
|-
 
|-
 
|06:00
 
|06:00
−
| Type '''plot brackets t comma sin(t) '''and press '''Enter.''' A '''sine plot '''is displayed.
+
| Type: '''plot brackets t comma sin(t) '''and press '''Enter.''' A '''sine plot '''is displayed.
  
 
|-
 
|-
 
| 06:14
 
| 06:14
−
| To study the '''plot''' better on the''' plot window,''' we can use various options that are available on it.
+
| To study the plot better on the''' plot window,''' we can use various options that are available on it.
 
Let us have a look at these options.  
 
Let us have a look at these options.  
  
 
|-
 
|-
 
| 06:25
 
| 06:25
−
| Moving the mouse pointer along the '''plot''' gives us the location of each '''point''' on the '''plot.'''
+
| Moving the '''mouse''' pointer along the '''plot''' gives us the location of each point on the plot.
  
 
|-
 
|-
 
| 06:33
 
| 06:33
−
| Notice here. At the bottom left of the window, there are a few buttons.
+
| Notice here, at the bottom left of the window, there are a few buttons.
  
 
|-
 
|-
 
|06:39
 
|06:39
−
| The right-most among them is for saving the file. Just click on it and type the '''file name'''.  
+
| The right-most among them is for saving the file. Just click on it and type the file name.  
  
 
|-
 
|-
 
|06:47
 
|06:47
−
| Let us save the '''plot''' by the name '''sin underscore curve''' in '''pdf format'''.  
+
| Let us '''save''' the '''plot''' by the name '''sin underscore curve''' in '''pdf format'''.  
  
 
|-
 
|-
 
| 06:54
 
| 06:54
−
| Click on the dropdown here.As you can see, there are many formats in which to save the '''file.
+
| Click on the dropdown here. As you can see, there are many formats in which to save the file.
 
Formats like '''png, eps, pdf''', and '''ps''' are available.  
 
Formats like '''png, eps, pdf''', and '''ps''' are available.  
  
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|-
 
|-
 
| 07:14
 
| 07:14
−
| To the left of the '''save '''button, is the '''slider button.''' Using this '''button''', we can specify the margins of the''' plot window'''.  
+
| To the left of the '''save '''button, is the '''slider''' button. Using this button, we can specify the margins of the''' plot window'''.  
  
 
|-
 
|-
 
| 07:24
 
| 07:24
−
| To the left of the '''slider button '''is the '''zoom''' '''button'''. It is used to '''zoom''' into the '''plot'''.
+
| To the left of the '''slider''' button is the '''zoom''' button . It is used to '''zoom''' into the '''plot'''. Just specify the region to '''zoom''' into.  
−
Just specify the region to '''zoom''' into.  
+
  
 
|-
 
|-
 
| 07:37
 
| 07:37
−
| The button to the left of '''zoom '''can be used to move the '''axes '''of the '''plot'''.  
+
| The button to the left of '''zoom, '''can be used to move the '''axes '''of the '''plot'''.  
  
 
|-
 
|-
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|-
 
|-
 
| 07:57
 
| 07:57
−
| The last one is ''''home'''' referring to the initial '''plot. '''
+
| The last one is ''''home'''', referring to the initial '''plot. '''
  
 
|-
 
|-
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| Plot '''(sin(x) multiplied by sin(x)) divided by x'''.  
 
| Plot '''(sin(x) multiplied by sin(x)) divided by x'''.  
  
−
1. Save the '''plot''' as '''sinsquarebyx dot pdf'''
+
1. '''Save''' the '''plot''' as '''sinsquarebyx dot pdf'''.
  
 
2. '''Zoom''' and find the '''maxima'''.
 
2. '''Zoom''' and find the '''maxima'''.
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|-
 
|-
 
| 08:26
 
| 08:26
−
|This brings us to the end of this tutorial. In this tutorial, we have learnt to,
+
|This brings us to the end of this tutorial. In this tutorial, we have learnt to:
  
−
Start '''IPython''' with '''pylab'''.
+
start '''IPython''' with '''pylab''',
  
−
Use the '''linspace''' function to create equally spaced points in a region.
+
use the '''linspace''' function to create equally spaced points in a region,
 
   
 
   
 
|-
 
|-
 
|08:42
 
|08:42
−
|Find the length of sequences using '''len''' '''function'''.
+
|find the length of sequences using '''len''' '''function''',
  
−
Plot mathematical functions using '''plot'''.
+
plot mathematical functions using '''plot''',
 
   
 
   
−
Clear drawing area using '''clf'''.  
+
clear drawing area using '''clf'''.  
  
 
|-
 
|-
 
|08:53
 
|08:53
−
| . Usage of buttons in the '''UI''' of the plot window such as -<br/> '''save''', '''zoom,''' '''move''' '''axis''', '''back''' and '''forward '''and '''Home '''
+
|usage of buttons in the '''UI''' of the plot window such as -<br/> '''save''', '''zoom,''' '''move axis''', '''back and forward, ''' '''Home. '''
  
 
|-
 
|-
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| Here are some self assessment questions for you to solve -
 
| Here are some self assessment questions for you to solve -
  
−
1. Create 100 equally spaced points between '''minus pi by 2''' and '''pi by 2'''
+
1. Create 100 equally spaced points between '''minus pi by 2''' and '''pi by 2'''.
  
 
|-
 
|-
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|-
 
|-
 
| 09:26
 
| 09:26
−
| And the answers,
+
| And the answers are-
  
 
We use the command '''linspace(minus pi by 2 comma pi by 2 comma 100)''' to create 100 equally spaced lines between the points '''minus pi by 2''' and '''pi by 2'''.
 
We use the command '''linspace(minus pi by 2 comma pi by 2 comma 100)''' to create 100 equally spaced lines between the points '''minus pi by 2''' and '''pi by 2'''.
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|-
 
|-
 
| 10:06
 
| 10:06
−
| The video at the following link summarises the Spoken Tutorial project.  If you do not have good bandwidth, you can download and watch it.  
+
| The video at the following link summarises the '''Spoken Tutorial''' project.  If you do not have good bandwidth, you can download and watch it.  
  
 
|-
 
|-
 
| 10:16
 
| 10:16
−
| We conduct workshops using Spoken Tutorials and give Certificates. Please contact us.  
+
| We conduct workshops using Spoken Tutorials and give certificates. Please contact us.  
  
 
|-
 
|-
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|-
 
|-
 
| 10:39
 
| 10:39
−
| Do you have any general / technical questions? Please visit the forum given in the link.  
+
| Do you have any general / technical questions? Please visit the forum given in this link.  
  
 
|-
 
|-
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|-
 
|-
 
| 11:00
 
| 11:00
−
| The Spoken Tutorial project is funded by NMEICT, MHRD, Govt. of India  
+
| The Spoken Tutorial project is funded by '''NMEICT, MHRD,''' Govt. of India.
  
 
|-
 
|-
 
| 11:07
 
| 11:07
−
| This is Usha from IIT Bombay signing off. Thanks for watching.
+
| This is Usha from '''IIT Bombay''', signing off. Thanks for watching.
  
 
|}
 
|}

Latest revision as of 17:27, 11 June 2019

Time Narration
00:01 Hello friends! Welcome to the tutorial on using plot command interactively in IPython.
00:08 At the end of this tutorial, you will be able to:

create simple plots of mathematical functions,

use the Plot window to study plots better.

00:20 To record this tutorial, I am using:

Ubuntu Linux 14.04 operating system,

Python 3.4.3 and

IPython 5.1.0

00:34 Pre-requisites to practise this tutorial are -

you should know how to run basic Python commands on the ipython console.

00:44 If not, for relevant Python tutorials, please visit this website.
00:50 Let us first open the Terminal by pressing Ctrl+Alt+T keys simultaneously.
00:58 Now, type ipython3 and press Enter.
01:05 Let us initialise the pylab package. Type: percentage pylab and press Enter.
01:16 Let's first understand what is Pylab.
01:20 Pylab is a convenient Python module

which provides- plotting functionality and has mathematical and scientific functions.

01:32 After running percentage pylab in the iPython console, you will see a message-

“Using matplotlib backend: TkAgg ”.

01:41 This means matplotlib is running.
01:45 But sometimes you may get an error that says-

“ImportError: No module named matplotlib”.

01:55 In such cases, you have to install matplotlib and run this command again.
02:02 Let's come back to the ipython console. Type 'linspace' followed by a question mark in ipython console. Press Enter.
02:14 Please note that the command is linspace and not linespace.
02:20 The displayed information says that

linspace returns evenly spaced numbers which are calculated over the interval start and stop.

02:34 Press q to exit the documentation and return to the console.
02:41 Let's try to generate 100 points from 1 to 100. Type: linspace brackets 1 comma 100 comma 100
02:58 Here, 1 is the start , 100 is the stop and the next 100 is the number of points. Now, press Enter.
03:09 As you can see, a sequence of numbers from 1 to 100 is displayed.
03:15 Now let's try to generate 200 points between 0 and 1.
03:21 We do that by typing linspace brackets 0 comma 1 comma 200 and press Enter.
03:36 Here is the expected sequence of numbers.
03:40 In linspace, the start and stop points can be integers, decimals or constants.
03:48 Let us now learn about the len function.
03:52 First we will generate 100 points between minus pi and pi.
03:58 So, type: linspace brackets minus pi comma pi comma 100 and press Enter.
04:10 Here 'pi' is a constant defined by pylab.
04:15 Now, let us save this to a variable, say t. Press Enter.
04:22 If we now type: len bracket t and press Enter, we will get the number of points between minus pi and pi.
04:32 len function gives the no. of elements present in a given sequence.
04:37 Next, let's try and plot a cosine curve between minus pi and pi.
04:43 For this, we use the plot command. Type: plot brackets t comma cos(t) and press Enter.
04:59 As you can see from the cosine plot, cos(t) gets the cosine value at every point corresponding to point t.
05:09 We can also assign the value of cos(t) to a variable cosine by typing cosine equals to cos(t). Press Enter.
05:21 And then plot by typing plot(t comma cosine) and press Enter.
05:31 To clear the plot, we have to use the clf() function. This avoids overlapping of new plots over older plots.
05:42 In the console, type: clf() and press Enter. The previous plot is cleared and a blank plot window is displayed.
05:56 Now, let's try to plot a sine plot.
06:00 Type: plot brackets t comma sin(t) and press Enter. A sine plot is displayed.
06:14 To study the plot better on the plot window, we can use various options that are available on it.

Let us have a look at these options.

06:25 Moving the mouse pointer along the plot gives us the location of each point on the plot.
06:33 Notice here, at the bottom left of the window, there are a few buttons.
06:39 The right-most among them is for saving the file. Just click on it and type the file name.
06:47 Let us save the plot by the name sin underscore curve in pdf format.
06:54 Click on the dropdown here. As you can see, there are many formats in which to save the file.

Formats like png, eps, pdf, and ps are available.

07:08 We have to specify the format that we prefer at the time of saving.
07:14 To the left of the save button, is the slider button. Using this button, we can specify the margins of the plot window.
07:24 To the left of the slider button is the zoom button . It is used to zoom into the plot. Just specify the region to zoom into.
07:37 The button to the left of zoom, can be used to move the axes of the plot.
07:41 The next two buttons with left and right arrow icons, change the state of the plot.
07:48 It takes us to the previous or next state of the plot. It acts like the back and forward button in a browser.
07:57 The last one is 'home', referring to the initial plot.
08:03 Pause the video here, try out the following exercise and then resume the video.
08:09 Plot (sin(x) multiplied by sin(x)) divided by x.

1. Save the plot as sinsquarebyx dot pdf.

2. Zoom and find the maxima.

3. Bring it back to initial position.

08:26 This brings us to the end of this tutorial. In this tutorial, we have learnt to:

start IPython with pylab,

use the linspace function to create equally spaced points in a region,

08:42 find the length of sequences using len function,

plot mathematical functions using plot,

clear drawing area using clf.

08:53 usage of buttons in the UI of the plot window such as -
save, zoom, move axis, back and forward, Home.
09:04 Here are some self assessment questions for you to solve -

1. Create 100 equally spaced points between minus pi by 2 and pi by 2.

09:15 2. How can we find the length of a sequence ?
09:19 3. What will the command linspace(minus pi comma pi comma 100) do?
09:26 And the answers are-

We use the command linspace(minus pi by 2 comma pi by 2 comma 100) to create 100 equally spaced lines between the points minus pi by 2 and pi by 2.

09:43 len(sequence underscore name) is the function used to find out the length of a sequence.
09:50 The command linspace(minus pi comma pi comma 100) will return 100 evenly spaced samples from -pi to pi including both minus pi and pi.
10:06 The video at the following link summarises the Spoken Tutorial project. If you do not have good bandwidth, you can download and watch it.
10:16 We conduct workshops using Spoken Tutorials and give certificates. Please contact us.
10:24 Do you have questions in THIS Spoken Tutorial?
10:27 Choose the minute and second where you have the question. Explain your question briefly.

Someone from the FOSSEE team will answer them. Please visit this site.

10:39 Do you have any general / technical questions? Please visit the forum given in this link.
10:46 The FOSSEE team coordinates coding of solved examples of popular books.
10:51 We give honorarium and certificates for those who do this. For more details, please visit this site.
11:00 The Spoken Tutorial project is funded by NMEICT, MHRD, Govt. of India.
11:07 This is Usha from IIT Bombay, signing off. Thanks for watching.

Contributors and Content Editors

Pratik kamble, Sandhya.np14

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