Python/C2/Additional-features-of-IPython/English-timed

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".
0:24	Let us start ipython with pylab loaded, by typing ipython space hyphen pylab on the terminal.
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 cosx and hit enter
1:00	We got an error saying "xsinx is not defined".
1:04	This is because xsin(x) is actually x star sin(x), for that we have to type on the terminal plot within bracket x comma x star sin(x) plot x, sin(x) xlabel within bracket in double quotes x then ylabel within bracket in double quotes dollar sign f(x) again a dollar sign then title within bracket in double quotes x and xsin(x) then again title within bracket in double quotes dollar sign x and xsin(x) and again a dollar sign
2:15	We now have the plot.
2:18	Let us look at the commands that we have typed in.
2:21	The history can be retrieved by using modulo hist command.
2:28	Type modulo that is percentage sign then hist and hit enter
2:37	As you can see, it displays a list of recent commands that we typed.
2:41	Every command has a number in front, to specify in which order and when it was typed.
2:48	So, Please note that there is a percentage sign before the hist command.
2:52	This implies that percentage hist is a command that is specific to IPython only and not to any other version of python.
3:00	These other type of commands are called as magic commands.
3:04	Also note that, the =%hist= itself is a command and is displayed as the most recent command.
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.
3:27	If we want only the recent 5 commands to be displayed, we pass the number as an argument to =percentage hist= command.
3:35	Hence percentage hist 5 displays the recent 5 commands, inclusive of the =percentage hist= command.
3:46	The default number is 40.
3:48	So to try this we can type in the terminal percentage hist space 5 and hit enter.
3:58	Pause the video here, try out the following exercise and resume the video.
4:02	Read through the documentation of %hist and find out how to list all the commands between 5 and 10.
4:11	As we can see from =percentage hist= documentation,percentage hist 5 10 displays the commands from 5 to 10
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.
4:35	we would like to save the required line of code from history.
4:39	This is possible by using the =percentage save= command.
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.
4:58	The first command is linspace.
5:00	But second command is a command that gave us an error.
5:06	Hence we do not need second command.
5:09	The commands from third to sixth are required.
5:12	The seventh command although is correct, we do not need it since we are setting the title correctly in the eighth command.
5:20	So we need first third to sixth and the eighth command for our program.
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
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.
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.
6:08	Pause the video here, try out the following exercise and resume the video.
6:11	Change the label on y-axis to "y" and save the lines of code accordingly.
6:17	we use the command =ylabel= on interpreter
6:21	ylabel within brackets in double quotes y and hit enter
6:29	and then you can do percentage save command
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
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.
6:58	We use the IPython magic command =percentage run= to do this.
7:03	Type percentage run space hyphen i space slash home slash fossee slash plot underscore script dot py
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.
7:27	Hence to view the plot type show then brackets on your terminal
7:38	So now Pause the video here, try out the following exercise and resume the video.
7:41	Use percentage hist and percentage save and create a script that has the function show() in it.
7:49	Run the script to produce the plot and display the name.
7:56	So you can type percentage hist space 20 on the terminal
8:06	We first look at the history using this command only,
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 , 14 and 17
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 get the plot.
9:03	We get the desired plot now.
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.
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.
9:32	Pause the video here, try out the following exercise and resume the video.
9:36	Run the script without using the hyphen i option.
9:42	Do you find any difference?
9:47	So you can type percentage run slash home slash fossee slash included hypen included dot py
10:04	We see that it raises Name Error saying that the name linspace is not found.
10:12	This brings us to the end of this tutorial.
10:14	In this tutorial,we have learnt to, Retrieve the history using =percentage hist= command.
10:21	then View only a part of history by passing an argument to 'percentage hist' command.
10:25	then Save the required lines of code in required order using 'percentage save' command.
10:30	then Use 'percentage run hyphen i' command to run the saved script.
10;39	Here are some self assessment questions for you to solve
10:43	5. How do you retrieve the recent 5 commands
10:46	And there are four options percentage hist,percentage hist minus 5,percentage hist 5,percentage hist 5 to 10
10:57	How do you save the lines 2 3 4 5 7 9 10 11 and the options are percentage save filepath 2 hyphen 5 7 9 hyphen 11,percentage save filepath 2 hyphen 11,percentage save filepath percentage save 2 hyphen 5 7 9 10 11
11:24	And the final question is What will the command percentage hist 5 10 display.
11:30	The recently typed commands from 5 to 10 inclusive of the history command
11:34	The recently typed commands from 5 to 10 excluding the history command
11:38	So now the answers,
11:41	In order to retrieve the recently typed 5 commands,we say percentage hist 5 for the first question.
11:49	So second question answer is percentage save file path 2 hyphen 5 space 7 space 9 hyphen 11 is the correct option to the specified lines of codes.
12:02	Then third answer is percentage hist 5 space 10 will display the recently typed commands from 5 to 10 inclusive of the history command.
12:14	This brings us to the end of this tutorial
12:17	So we Hope you have enjoyed and found it useful.Thank you.

Contributors and Content Editors

Gaurav, Kavita salve, Krupali, Minal, PoojaMoolya, Sneha