diff -r 7206fe0c03c5 -r b595f90016c5 getting-started-ipython.rst --- a/getting-started-ipython.rst Wed Oct 06 15:08:52 2010 +0530 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,174 +0,0 @@ -======== - Script -======== - -Welcome to so and so.. - - -This tutorial will cover the basic usage of the ``ipython`` -interpreter. The following topics would be covered. - -{{{ Show slide with outline of the session. }}} - -IPython is an enhanced Python interpreter that provides features like -tabcompletion, easier access to help and many other functionalities -which are not available in the vannila 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. - -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 to the required one. 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, the 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. - -%% %% Pause the video here and type ``ab`` and hit tab to see what -happens. Next, jut type ``a`` and hit tab to see what happens. - -``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. - -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. - -%% %% Pause the video here, and look-up the documentation of ``round`` -and see how to use it. - -:: - - 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. - -%% %% Pause the video here and check the output of -round(2.48) -round(2.48, 1) -round(2.48, 2) -and then resume the video. - -:: - round(2.484) - round(2.484, 1) - round(2.484, 2) - -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 when 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. - -%% %% Pause the video here. -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. - -:: - - round(2.484 - ^C - - round(2.484, 2) - -This brings us to the end of the tutorial on getting started with -``ipython``. - -In this tutorial we have seen -{{{ show the outline/summary slide. }}} - -Thank you! - - -