View source for Python/C2/Additional-features-of-IPython/English-timed

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!Timing
!Narration
|-
| 0:00
| Hello friends and welcome to the tutorial on "Additional Features of IPython".

|-
| 0:06
| At the end of this tutorial, you will be able to,

# Retrieve your ipython history.
# View a part of the history.
# Save a part of your history to a file.
# Run a script from within ipython.



|-
| 0:19
| Before beginning this tutorial,we would suggest you to complete the tutorial on "Embellishing a plot".

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|0:24
|Let us start ipython with pylab loaded, by typing ipython  hyphen pylab on the terminal.

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| 0:33
| We shall first make a plot and then view the history and save it, for that we can type x = linspace within brackets minus 2 into pi comma 2 into pi comma 100

plot within bracket x comma  xsinx within bracket x and hit enter


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|1:00
| We got an error saying "xsinx is not defined".

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|1:04
|This is because xsin(x) is actually x star sin(x), for that we have type in the terminal
plot within bracket x comma x star sin(x)

plot within bracket x, sin(x)
xlabel within bracket in double quotes x
ylabel within bracket in double quotes  dollar sign f(x) dollar sign
title within bracket in double quotes x and xsin(x)
title within bracket in double quotes dollar sign x and xsin(x) dollar sign


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|  2:15
| We now have the plot. 

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|2:18
|Let us look at the commands that we have typed in.

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|2:21
| The history can be retrieved by using =modulo hist= command.

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|2:28
| Type  modulo that is percentage sign hist in your terminal and hit enter

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| 2:37
| As you can see, it displays a list of recent commands that we typed.

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|2:41
| Every command has a number in front, to specify in which order and when it was typed.

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|2:48
|Please note that there is a percentage sign before the hist command.

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|2:52
| This implies that percentage hist is a command that is specific to IPython only and not to any other version of python.

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|3:00
| These type of commands are called as magic commands.

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|3:04
|Also note that, the =%hist= itself is a command and is displayed as the most recent command.

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|3:15
| We should note that anything we type in is stored as history, irrespective of whether it is command or an error or IPython magic command.

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| 3:27
| If we want only the recent 5 commands to be displayed, we pass the number as an argument to =percentage hist= command.

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|3:35
| Hence percentage hist 5 displays the recent 5 commands, inclusive of the =percentage hist= command. 

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|3:46
|The default number is 40.

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|3:48
|So to try this we can type in the terminal percentage hist space 5 and hit enter.

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| 3:58
| Pause the video here, try out the following exercise and resume the video.

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|4:02
|Read through the documentation of %hist and find out how to list all the commands between 5 and 10.

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| 4:11
| As we can see from =percentage hist= documentation,percentage hist 5 10 displays the commands from 5 to 10

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|4:22
|Now that we have the history, we will try it on the command prompt so type percentage hist 5 space 10 and hit enter.

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|4:35
| we would like to save the required line of code from history.

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|4:39
| This is possible by using the =percentage save= command.

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|4:47
| Before we do that, let us first look at history and identify what lines of code we require. So type percentage hist and hit enter.

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| 4:58
| The first command is linspace.

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| 5:00
| But second command is a command that gave us an error.

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|5:06
| Hence we do not need second command.

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|5:09
| The commands from third to sixth are required. 

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|5:12
|The seventh command although is correct, we do not need it since we are setting the title correctly in the eighth command.

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| 5:20
| So we need first third to sixth and the eighth command for our program.

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|5:26
| Hence you can type in the syntax of percentage save slash home slash fossee slash plot underscore script dot py space 1 space 3 hyphen 6 space 8

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|  5:46
| The command saves the first line of code and then third to sixth followed by the eighth lines of code into the specified file.

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|5:55
|The first argument to percentage save is the path of file to save the commands and the arguments there after are the commands to be saved in the given order.

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| 6:08
| Pause the video here, try out the following exercise and resume the video.

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|6:11
|Change the label on y-axis to "y" and save the lines of code accordingly.

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| 6:17
| we use the command =ylabel= on interpreter

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|6:21
|ylabel within brackets in double quotes y and hit enter

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| 6:29
| and then you can do percentage save command

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|6:36
| That is you can type percentage save slash home slash fossee slash example underscore plot dot py space 1 space 3 hyphen 6 space 10

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|6:51
| Now that we have the required lines of code in a file, let us learn how to run the file as a python script.

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|6:58
|We use the IPython magic command =percentage run= to do this. 

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|7:03
|Type percentage run spce hyphen i space slash home slash fossee slash plot underscore script dot py 

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|7:18
| The script runs but we do not see the plot. This happens because when we are running a script, we are not in the interactive mode anymore.

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|7:27
|Hence to view the plot type <tt>show then brackets</tt> on your terminal

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| 7:38
| Pause the video here, try out the following exercise and resume the video.

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|7:41
|Use percentage hist and percentage save and create a script that has the function show() in it.

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|7:49
| Run the script to produce the plot and display the same.

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|7:56
|So you can type percentage hist space 20 on the terminal

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|8:06
|We first look at the history using this command

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| 8:09
| Then save the script using the command percentage save space  slash home slash fossee slash show underscore included dot py space  1  space 3 hyphen 6  space 8  space 14 space 17

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|8:37
| then on the next line you can type
percentage run hyphen i slash home slash fossee slash show underscore included dot py, then type show function to gt the plot.

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| 9:03
| We get the desired plot now.

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|9:07
|The reason for including a hyphen i after run is to tell the interpreter that if any name is not found in script, search for it in the interpreter. 

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|9:17
|Hence all these sin, plot, pi and show which are not available in script, are taken from the interpreter and used to run the script.

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| 9:32
| Pause the video here, try out the following exercise and resume the video.

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|9:36
|Run the script without using the hyphen i option. 

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|9:42
|Do you find any difference?

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|9:47
|So you can type percentage run slash home slash fossee slash show underscore included dot py

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|  10:04
| We see that it raises NameError saying that the name linspace is not found.

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|10:12
| This brings us to the end of this tutorial. 

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|10:14
|In this tutorial,we have learnt to, Retrieve the history using =percentage hist= command.

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|10:21
|then View only a part of history by passing an argument to 'percentage hist' command.

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|10:25
|then Save the required lines of code in required order using 'percentage save' command.

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|10:30
|then Use 'percentage run hyphen i' command to run the saved script.



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| 10;39
| Here are some self assessment questions for you to solve

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|10:43
|5. How do you retrieve the recent 5 commands

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|10:46
| And there are four options <tt>percentage hist</tt>,  <tt>percentage hist  minus 5</tt>, <tt>percentage hist 5</tt>,  <tt>percentage hist 5 to 10</tt>

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|10:57
|How do you save the lines 2 3 4 5 7 9 10 11 and the options are <tt>percentage save filepath 2 hyphen 5 7 9 hyphen 11</tt>,  <tt>percentage save filepath 2 hyphen 11</tt>, <tt>percentage save filepath</tt>
 <tt>percentage save 2 hyphen 5 7 9 10 11</tt>

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|11:24
|And the final question is What will the command <tt>percentage hist 5 10</tt> display.

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|11:30
| The recently typed commands from 5 to 10 inclusive of the history command

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|11:34
|The recently typed commands from 5 to 10 excluding the history command

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| 11:38
| So now the answers,

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|11:41
| In order to retrieve the recently typed 5 commands,we say <tt>percentage hist 5</tt>.

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|11:49
|So second question answer is <tt>percentage save filepath 2 hyphen 5 space  7  space 9 hyphen 11</tt> is the correct option to the specified lines of codes.

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|12:02
| Then third answer is<tt>percentage hist 5 space 10</tt> will display the recently typed commands from 5 to 10 inclusive of the history command.

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| 12:14
| This brings us to the end of this tutorial

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| 12:17
|So we Hope you have enjoyed and found it useful.Thank you.