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Revision as of 15:24, 7 March 2017

Additional-features-of-IPython - English


Title: Additional-features-of-IPython – English

Author: Usha Viswanathan, Thirumalesh H S

Keywords: Video tutorial, IPython, running script, saving script,


Visual Cue
Narration
Show Slide

containing title, name of the production team along with the logo of MHRD

Hello friends and welcome to the Spoken Tutorial on Additional Features of IPython.
Show Slide

Objectives

At the end of this tutorial, you will be able to,
  1. Retrieve your IPython history.
  2. View a part of the history.
  3. Save a part of a history to a file.
  4. Run a script from within IPython.


Show Slide

System Specifications

To record this tutorial, I am using
  • Ubuntu Linux 14.04 operating system
  • Python 3.4.3
  • IPython 5.1.0


Show Slide

Pre-requisites

To practice this tutorial, you should know how to
  • use Plots interactively
  • and embellish a plot

If not, see the pre-requisite Python tutorials on this website.

[Terminal]

ipython3


Let us now open the Terminal by pressing Ctrl+Alt+T keys simultaneously.


Now, type ipython3 and press Enter.

[IPython console]

%pylab and press Enter.

Let us initialise the pylab package.


Type percentage pylab and press Enter

[IPython Terminal]


x = linspace(-2*pi, 2*pi, 100)

press Enter

To start plotting, type x equals to linspace inside the brackets minus 2*pi comma 2*pi comma 100 then press Enter.
[IPython Terminal]


plot(x, xsin(x))

press Enter

Next type plot inside the brackets x comma xsin(x) and then press Enter



Highlight the message “xsin is not defined” on the terminal. We got an error saying "xsin is not defined".


This is because xsin(x) is actually x multiplied by sin(x)

[IPython Terminal]


plot(x, x*sin(x))

Press Enter


Here, multiplication sign is missing. So let us type

plot inside the brackets x comma x multiplied by sin(x) and press Enter.

[IPython Terminal]


Type


xlabel("$x$")


ylabel("$f(x)$")


title("$x and xsin(x)$")


Next let us add title and the labels for both x and y axes.


Type

xlabel inside the brackets inside inverted commas inside dollar sign x press Enter.


Ylabel inside the brackets inside inverted commas inside dollar sign f(x) press Enter.


Title inside the brackets inside inverted commas inside dollar sign x and xsin(x) press Enter.


We can now see the labelled plot.

[IPython Terminal]

Type

%history

and press Enter

The history of typed commands can be retrieved by %history command.


Type %history and press Enter.

%history itself is a command and is displayed as the most recent command.


Whatever we executed in the terminal is stored as history.

[IPython Terminal]


Type

%history 5

press Enter

If we want to see what was the fifth command, pass 5 as an argument to %history command.


Type %history space 5 and press Enter. This displays the fifth command which we typed.

Show Slide

Assignment 1

Now pause the video here, try out the following exercise and resume the video.


Find out how to list the recent commands between 5 and 10.

Switch back to terminal.
[IPython terminal]


In examples of history doc, highlight

Example >> %history -n 4-6

Now quit history doc and type

%history 5-10 and press Enter

Let us look at the solution.


Type clf()


Type %history?


Read through the information of %history command.


We can see, %history hypen n 4 hypen 6 displays the commands from 4 to 6.

Here hypen n is optional argument which prints line numbers.


Type q to quit the documentation


Now type %history space 5hypen 10 and press Enter.

To save the history, we use %save command.
[IPython Terminal]

Type %history and press Enter

Before we do that, let us first look at the history and identify which lines of code we require.


Type %history and press Enter.

[IPython Terminal]

Highlight the commands on the terminal.

The second command is linspace. But the third command is a command that gave us an error.


Hence we do not need it. The commands from fourth to seventh are required.

[IPython Terminal]

Type

%save plot_script.py 2 4-7

and press Enter

So we need the second command and then the fourth to seventh commands for our program.


Let us save it in the present working directory. Hence the syntax will be

%save space plot_script.py 2 space 4 hypen 7. press Enter

[IPython Terminal]

Highlight the typed command on the terminal.

The first argument in %save command is the name of the file in which the commands are saved.

The second argument gives the numbers of the commands that are being saved separated by spaces.

[File Browser]


Goto file plot_script.py. open and show it

Let us now open the file plot_script.py and see the contents.
[IPython Terminal]

Type

%run -i plot_script.py

and press Enter

Let us learn how to run the file as a python script.


We use the command %run to do this.


Type %run space hypen i space plot_script.py and press Enter.


Here, hypen i parameter runs the code written in a text editor.


The code is run within the current ipython session.


It uses the variables defined interactively in the ipython session.

[IPython Terminal]

Type

show()

and press Enter


The script runs but we do not see the plot.


This is because when we are running a script,

we are not in the interactive mode.


To view the plot, type show() on your terminal. Press Enter.

Show Slide

Assignment 2


Pause the video here, try out the following exercise and resume the video.


Use %history and %save to create a script that has the function show() in it.


Run the script to produce the plot and display the same.

[IPython Terminal]

%history -n

press Enter


Let us look at the solution.


We first look at the history using %history hypen n command.

Type %history hypen n and press Enter.

[IPython Terminal]


Type clf()

press Enter

Let us clear the plot window


Type clf() and press Enter

[IPython Terminal]

Type

%save show_included.py 1 3-7 12 15

Press Enter


Now let us save the script using the command %save

We need lines 2, 4 to 7 and 16

Type

%save show_included.py 2 space 4 hypen 7 space 16 and press Enter

[IPython Terminal]

Type


%run -i show_included.py

Press Enter

To run the script type


%run hypen i show_included.py


Then press Enter

We get the desired plot.
[IPython Terminal]

Go to the previous command. Modify it by removing ‘-i’ in the command to, %run show_included.py


and Press Enter

Go to the previous command. Modify it by removing ‘hypen i’ in the command to,

%run show_included.py


We see that it raises a NameError saying that the name linspace is not found


This happens because we did not run the script interactively.



Show Slide

Summary

This brings us to the end of this tutorial. In this tutorial,we have learnt to,
  1. Retrieve the history using %history command.
  1. View only a part of history by passing argument to %history command.


Show Slide

Summary

# Save the required lines of code in required order using '%save' command.
  1. Use '%run -i' command to run a saved script.


Show Slide

Self assessment 1

* How do you save the command lines 2 3 4 5 7 9 10 11
    • %save <filename> 2-5 7 9-11
    • %save <filename> 2-11
    • %save <filename>
    • %save 2-5 7 9-11


Show Slide

Self assessment 2

* Which is the command to run the script?
    • %execute <script name>
    • %run -i <script name>
    • %run <script name>
    • %execute -i <script name>


Show Slide

Solution for the self assessment questions

And the answers,
  1. To save the commands 2 3 4 5 7 9 10 11, we issue the command %save <filename> 2-5 7 9-11
  1. To run the script we use %run -i <scriptname>


Show Slide

Forum

Please post your timed queries in this forum.
Show Slide

Fossee Forum

Please post your general queries on Python in this forum.
Show Slide

Textbook Companion

FOSSEE team coordinates the TBC project.
Show Slide

Acknowledgment

http://spoken-tutorial.org

Spoken Tutorial Project is funded by NMEICT, MHRD, Govt. of India.

For more details, visit this website.

Previous slide This is _________ from IIT Bombay (or FOSSEE, if you wish) signing off.

Thank you.

Contributors and Content Editors

Nancyvarkey, Nirmala Venkat, Vineeta

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