diff -r 88a01948450d -r d33698326409 getting_started_with_ipython/script.rst --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/getting_started_with_ipython/script.rst Wed Dec 01 16:51:35 2010 +0530 @@ -0,0 +1,235 @@ +.. Objectives +.. ---------- + +.. At the end of this tutorial, you will be able to + +.. 1. invoke the ``ipython`` interpreter. +.. #. quit the ``ipython`` interpreter. +.. #. navigate in the history of ``ipython``. +.. #. use tab-completion. +.. #. look-up documentation of functions. +.. #. interrupt incomplete or incorrect commands. + +.. Prerequisites +.. ------------- + +.. should have ``ipython`` and ``pylab`` installed. + +.. Author : Puneeth + Internal Reviewer : Anoop Jacob Thomas + Language Review : Bhanukiran + External Reviewer : + Checklist OK? : [2010-10-05] + + +Script +------ + +{{{ Show the slide containing title }}} + +Hello Friends and Welcome to the tutorial on getting started with +``ipython``. + +{{{ Show slide with outline }}} + +This tutorial will cover the basic usage of the ``ipython`` +interpreter. The following topics would be covered. + +IPython is an enhanced Python interpreter that provides features like +tabcompletion, easier access to help and lot of other functionality +which are not available in the vanilla Python interpreter. + +First let us see how to invoke the ``ipython`` interpreter. + +We type +:: + + ipython + +at the terminal prompt to invoke the ipython interpreter. + +We get a prompt with ``In [1]:`` after getting some information about +the version of Python installed and some help commands. + +If you get an error saying something like ``ipython is not +installed``, refer to the tutorial on how to install the packages +required for this course. + +Now, to quit the ipython interpreter, type Ctrl-D. You are prompted +asking if you really want to exit, type y to say yes and quit ipython. + +Start ipython again, as you did before. + +The prompt that you have says ``In [1]``. ``In`` stands for input and the +ipython interpreter is ready to accept input from you. + +Now let us see, how we can type some commands into the interpreter. + +Start with the simplest thing, addition. + +Let's type +:: + 1+2 + +at the prompt. IPython promptly gives back the output as 3. Notice +that the output is displayed with an ``Out[1]`` indication. + +.. #[[Anoop: I think we can illustrate In [] and Out[] in slides]] +.. #[[Puneeth: I think we can do that on the terminal?]] + +Let's try out few other mathematical operations. +:: + + 5 - 3 + 7 - 4 + 6 * 5 + +Now let's ``print 1+2``. Instead of typing the whole thing, we make +use of the fact that IPython remembers the history of the commands +that you have already used. We use the up arrow key to go back the +command ``1+2``. We then use the left-arrow key to navigate to the +beginning of the line and add the word ``print`` and a space. Then hit +enter and observe that the interpreter prints out the value as 3, +without the Out[] indication. + +Now, let's change the previous command ``print 1+2`` to ``print +10*2``. We use the up arrow again to navigate to the previous command +and use the left arrow key to move the cursor on to the + symbol and +then use the delete key to remove it and type 0 and * to change the +expression as required. We hit enter to see the output of +``print``. + +Now, let's say we want to use the function ``round``. We type ``ro`` +at the prompt and hit the tab key. As you can see, IPython +completes the command. This feature is called the tab-completion. + +Now, we remove all the characters and just type ``r`` and then hit +tab. IPython does not complete the command since there are many +possibilities. It just lists out all the possible completions. + +Following is an exercise that you must do. + +%%1%% Type ``ab`` and hit tab to see what happens. Next, just type +``a`` and hit tab to see what happens. + +Please, pause the video here. Do the exercise and then continue. + +``ab`` tab completes to ``abs`` and ``a`` gives us a list of all +the commands starting with a. + +Now, let's see what these functions are used for. We will use the +help features of ipython to find this out. + +.. #[[Anoop: Another slide which says about ? mark and round? etc, as + few people cannot just follow by listening (like me) :)]] + +.. #[Punch: These things are shown on the terminal. I feel we don't +.. need slide, here I guess.] + +To get the help of any function, we first type the function, ``abs`` +in our case and then add a ? at the end and hit enter. + +As the documentation says, ``abs`` accepts a number as an input and +returns it's absolute value. + +We say, +:: + + abs(-19) + + abs(19) + +We get 19, as expected, in both the cases. + +Does it work for decimals (or floats)? Let's try typing abs(-10.5) +and we do get back 10.5. + +Following is an exercise that you must do. + +%%2%% Look-up the documentation of ``round`` and see how to use it. + +Please, pause the video here. Do the exercise and then continue. + +:: + + round? + +If you notice, there are extra square brackets around the ``ndigits``. +This means that ``ndigits`` is optional and 0 is the default value. +Optional parameters are shown in square brackets anywhere in Python +documentation. + +The function ``round``, rounds a number to a given precision. + +Following are exercises that you must do. + +%%3%% Check the output of:: + + round(2.48) + round(2.48, 1) + round(2.48, 2) + + round(2.484) + round(2.484, 1) + round(2.484, 2) + +Please, pause the video here. Do the exercises and then continue. + +We get 2.0, 2.5 and 2.48, which are what we expect. + +Let's now see how to correct typing errors that we make while typing at +the terminal. As already shown, if we haven't hit the enter key +already, we could navigate using the arrow keys and make deletions +using delete or backspace key and correct the errors. + +Let's now type round(2.484 and hit enter, without closing the +parenthesis. We get a prompt with dots. This prompt is the +continuation prompt of ``ipython``. It appears, the previous line is +incomplete in some way. We now complete the command by typing, the +closing parenthesis and hitting enter. We get the expected output of +2.5. + +In other instances, if we commit a typing error with a longer and more +complex expression and end up with the continuation prompt, we can +type Ctrl-C to interrupt the command and get back the ``ipython`` input +prompt. + +Following is an exercise that you must do. + +%%4%% Try typing round(2.484, and hit enter. and then cancel the +command using Ctrl-C. Then, type the command, round(2.484, 2) and +resume the video. + +Please, pause the video here. Do the exercises and then continue. + +:: + + round(2.484 + ^C + + round(2.484, 2) + +This brings us to the end of the tutorial on getting started with +``ipython``. + +.. #[[Anoop: add slides for interrupts, navigating history, I feel + even a single point will also do]] + +.. #[Puneeth: I don't feel these things cannot be shown on a slide.] + +In this tutorial we have learnt, how to +{{{ show the outline/summary slide. }}} + + 1. invoke the ``ipython`` interpreter. + #. quit the ``ipython`` interpreter. + #. navigate in the history of ``ipython``. + #. use tab-completion. + #. look-up documentation of functions. + #. interrupt incomplete or incorrect commands. + +{{{ Show the "sponsored by FOSSEE" slide }}} + +This tutorial was created as a part of FOSSEE project, NME ICT, MHRD India + +Hope you have enjoyed and found it useful. +Thank you!