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+.. Objectives
+.. ----------
+
+.. At the end of this tutorial, you will be able to
+
+.. 1. Assign default values to arguments, when defining functions
+.. 2. Define and call functions with keyword arguments.
+.. 3. Also, you will get a glimpse of the plethora of functions
+.. available, in Python standard library and the scientific computing
+.. libraries.
+
+
+.. Prerequisites
+.. -------------
+
+.. 1. getting started with ipython
+.. #. getting started with functions
+
+.. Author : Puneeth
+ Internal Reviewer : Anoop Jacob Thomas<anoop@fossee.in>
+ External Reviewer :
+ Language Reviewer : Bhanukiran
+ Checklist OK? : <put date stamp here, if OK> [2010-10-05]
+
+Script
+------
+
+{{{ Show the slide containing title }}}
+
+Welcome to the tutorial on advanced feature of functions.
+
+{{{ Show the outline slide }}}
+
+In this tutorial we shall be looking at specifying default arguments
+to functions when defining them and calling functions using keyword
+arguments. We shall also, look at some of the built-in functions
+available in the standard library of Python and the scientific
+computing libraries.
+
+{{{ switch to terminal }}}
+
+We have an ``ipython`` terminal open, which we shall be using through
+out this session.
+
+Let's use the ``round`` function as an example to understand what a
+default value of an argument means. Let's type the following
+expressions in the terminal.
+
+::
+
+ round(2.484)
+
+ round(2.484, 2)
+
+Both the first expression and the second are calls to the ``round``
+function, but the first calls it with only one argument and the second
+calls it with two arguments. By observing the output, we can guess
+that the first one is equivalent to call with the second argument
+being 0. 0 is the default value of the argument.
+
+.. #[[Anoop: It will be good if we show ``round??`` and tell them the
+ optional argument ndigits, or it could be given as an
+ exercise(solved) asking them to find the name of the argument in
+ the function round]]
+
+{{{ show a slide with examples of functions showing default values }}}
+
+.. #[[Anoop: I think the slide is not there]]
+
+::
+
+ s.strip() # strips on spaces.
+ s.strip('@') # strips the string of '@' symbols.
+
+ plot(x, y) # plots with x vs. y using default line style.
+ plot(x, y, 'o') # plots x vs. y with circle markers.
+
+ linspace(0, 2*pi, 100) # returns 100 points between 0 and 2pi
+ linspace(0, 2*pi) # returns 50 points between 0 and 2pi
+
+.. #[punch: all above content goes on to a slide]
+
+{{{ switch back to ipython }}}
+
+Let's now define a simple function that uses default arguments. We
+define a simple function that prints a welcome message to a person,
+given a greeting and his/her name.
+
+::
+
+ def welcome(greet, name="World"):
+ print greet, name
+
+Let us first call the function with two arguments, one for ``greet``
+and other for ``name``.
+
+::
+
+ welcome("Hi", "Guido")
+
+We get the expected welcome message, "Hi Guido".
+
+Now let us call the function with just one argument "Hello".
+::
+
+ welcome("Hello")
+
+"Hello" is treated as the ``greet`` and we get "Hello World" as
+the output. "World" is the default value for the argument ``name``.
+
+Following is an (are) exercise(s) that you must do.
+
+{{{ switch to next slide, containing problem statement of
+ question 1 }}}
+
+%%1%% Redefine the function ``welcome``, by interchanging it's
+arguments. Place the ``name`` argument with it's default value of
+"World" before the ``greet`` argument.
+
+Please, pause the video here. Do the exercise and then continue.
+
+{{{ switch to next slide, containing the solution to problem 1 }}}
+
+::
+
+ def welcome(name="World", greet):
+ print greet, name
+
+We get an error that reads ``SyntaxError: non-default argument follows
+default argument``. When defining a function all the argument with
+default values should come at the end.
+
+.. #[[Anoop: In the slide, "when defining a function all the default
+ arguments must be defined at the end" has to be emphasized"]]
+
+Following is an exercise that you must do.
+
+{{{ switch to next slide, containing the problem statement of
+ question 2 }}}
+
+%%2%% See the definition of linspace using ``?`` and observe how all
+the arguments with default values are towards the end.
+
+Please, pause the video here. Do the exercise and then continue.
+
+{{{ switch to next slide, containing solution to problem 2 }}}
+
+::
+
+ linspace?
+
+Following is an exercise that you must do.
+
+{{{ switch to next slide, problem statement }}}
+
+%%3%% Redefine the function ``welcome`` with a default value of
+"Hello" to the ``greet`` argument. Then, call the function without any
+arguments.
+
+Please, pause the video here. Do the exercise and then continue.
+
+{{{ switch to next slide, solution }}}
+
+::
+
+ def welcome(greet="Hello", name="World"):
+ print greet, name
+
+
+ welcome()
+
+
+Let us now learn what keyword arguments or named arguments are. We
+shall refer to them as keyword arguments, henceforth.
+
+{{{ show a slide with examples using keyword arguments. }}}
+
+.. #[[Anoop: slide is missing]]
+
+::
+
+ legend(['sin(2y)'], loc = 'center')
+
+ plot(y, sin(y), 'g', linewidth = 2)
+
+ annotate('local max', xy = (1.5, 1))
+
+ pie(science.values(), labels = science.keys())
+
+When you are calling functions in Python, you don't need to remember
+the order in which to pass the arguments. Instead, you can use the
+name of the argument to pass it a value. This slide shows a few
+function calls that use keyword arguments. ``loc``, ``linewidth``,
+``xy`` and ``labels`` are being called with keyword arguments.
+
+{{{ switch to ipython terminal }}}
+
+Let us try and understand this better using the ``welcome`` function
+that we have been using all along. Let us call it in different ways
+and observe the output to see how keyword arguments work.
+
+::
+
+ welcome()
+
+ welcome("Hello", "James")
+
+ welcome("Hi", name="Guido")
+
+When no keyword is specified, the arguments are allotted based on
+their position. So, "Hi" is the value of the argument ``greet`` and
+name is passed the value "Guido".
+::
+
+ welcome(name="Guido", greet="Hey! ")
+
+When keyword arguments are used, the arguments can be called in any
+order.
+
+::
+
+ welcome(name="Guido", "Hey")
+
+This call returns an error that reads, ``non keyword arg after keyword
+arg``. Python expects all the keyword to be present towards the end.
+
+That brings us to the end of what we wanted to learn about ``keyword``
+arguments.
+
+{{{ switch to a slide showing variety of functions with uses }}}
+
+.. #[[Anoop: slide missing]]
+
+Before defining a function of your own, make sure that you check the
+standard library, for a similar function. Python is popularly called a
+"Batteries included" language, for the huge library that comes along
+with it.
+
+::
+
+ Math functions - abs, sin, ....
+
+.. #[punch: Need to decide, exactly what to put here. Reviewer comments
+.. welcome.]
+
+{{{ switch to slide showing classes of functions in pylab, scipy }}}
+
+.. #[[Anoop: slide missing]]
+
+Apart from the standard library there are other libraries like ``pylab``,
+``scipy``, etc which have a huge collection of functions for scientific
+purposes.
+::
+
+ pylab
+ plot, bar, contour, boxplot, errorbar, log, polar, quiver, semilog
+
+ scipy (modules)
+ fftpack, stats, linalg, ndimage, signal, optimize, integrate
+
+{{{ Show summary slide }}}
+
+.. #[[Anoop: add range of functions available in python standard
+ library]]
+
+That brings us to the end of this tutorial. In this tutorial we have
+learnt how to use functions with default values and keyword
+arguments. We also looked at the range of functions available in the
+Python standard library and the Scientific Computing related
+packages.
+
+{{{ 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!