Difference between revisions of "Python/C2/Additional-features-of-IPython/English"

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Learning objectives

1. Retrieve your ipython history.
2. View a part of the history.
3. Save a part of your history to a file.
4. Run a script from within ipython.

Pre-requisite

Shift to terminal and type ipython -pylab

ipython -pylab

Let us start ipython with pylab loaded, by typing ipython -pylab on the terminal.

plot(x, xsinx(x))

plot(x, sin(x))
xlabel("x")
ylabel("$f(x)$")
title("x and xsin(x)")
title("$x and xsin(x)$")

Please note that there is a % sign before the hist command. This implies that %hist is a command that is specific to IPython only and not to any other version of python. These type of commands are called as magic commands.

Also note that, the =%hist= itself is a command and is displayed as the most ecent command. 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.

Assignment 1

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

%hist 5 10

Now that we have the history, we would like to save the required line of code from history. This is possible by using the =%save= command.

%save /home/fossee/plot_script.py 1 3-6 8

The first argument to %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.

Assignment 2

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

ylabel("y")

%save /home/fossee/example_plot.py 1 3-6 10

We use the IPython magic command =%run= to do this. Type

Hence to view the plot type show() on your terminal

Assignment 3

%hist 20

Use %hist and %save and create a script that has the function show() in it. Run the script to produce the plot and display the same.

<Pause>

We first look at the history using

%save /home/fossee/show_included.py 1 3-6 8 14 17
%run -i /home/fossee/show_included.py

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

Assignment 4

Run the script without using the -i option. Do you find any difference?

<Pause>

Summary slide

1. Retrieve the history using =%hist= command.
2. View only a part of history by passing an argument to '%hist' command.
3. Save the required lines of code in required order using '%save' command.
4. Use '%run -i' command to run the saved script.

Self assessment questions slide

1. How do you retrieve the recent 5 commands

• • %hist
  • %hist -5
  • %hist 5
  • %hist 5-10

1. How do you save the lines 2 3 4 5 7 9 10 11

• • %save filepath 2-5 7 9-11
  • %save filepath 2-11
  • %save filepath
  • %save 2-5 7 9 10 11

1. What will the command %hist 5 10 display.

• • The recently typed commands from 5 to 10 inclusive of the history command
  • The recently typed commands from 5 to 10 excluding the history command

Solution of self assessment questions on slide

1. In order to retrieve the recently typed 5 commands,we say %hist 5.
2. %save filepath 2-5 7 9-11 is the correct option to the specified lines of codes.
3. %hist 5 10 will display the recently typed commands from 5 to 10 inclusive of the history command.

Acknowledgment slide