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+.. Objectives
+.. ----------
+
+.. By the end of this tutorial, you will be able to
+
+.. 1. Slice strings and get sub-strings out of them
+.. #. Reverse strings
+.. #. Replace characters in strings.
+.. #. Convert strings to upper or lower case
+.. #. joining a list of strings
+
+.. Prerequisites
+.. -------------
+
+.. 1. getting started with strings
+.. #. getting started with lists
+.. #. basic datatypes
+
+.. Author : Puneeth
+ Internal Reviewer : Amit
+ External Reviewer :
+ Language Reviewer : Bhanukiran
+ Checklist OK? : <08-11-2010, Anand, OK> [2010-10-05]
+
+Script
+------
+
+{{{ Show the slide containing title }}}
+
+Hello Friends. Welcome to this tutorial on manipulating strings.
+
+{{{ show the slide with outline }}}
+
+In this tutorial we shall learn to manipulate strings, specifically
+slicing and reversing them, or replacing characters, converting from
+upper to lower case and vice-versa and joining a list of strings.
+
+We have an ``ipython`` shell open, in which we are going to work,
+through out this session.
+
+Let us consider a simple problem, and learn how to slice strings and
+get sub-strings.
+
+Let's say the variable ``week`` has the list of the names of the days
+of the week.
+
+::
+
+ week = ["sun", "mon", "tue", "wed", "thu", "fri", "sat"]
+
+
+Now given a string ``s``, we should be able to check if the string is a
+valid name of a day of the week or not.
+
+::
+
+ s = saturday
+
+
+``s`` could be in any of the forms --- sat, saturday, Sat, Saturday,
+SAT, SATURDAY. For now, shall now be solving the problem only for the forms,
+sat and saturday. We shall solve it for the other forms, at the end of
+the tutorial.
+
+{{{ show these forms in a slide }}}
+
+So, we need to check if the first three characters of the given string
+exists in the variable ``week``.
+
+As, with any of the sequence data-types, strings can be sliced into
+sub-strings. To get the first three characters of s, we say,
+
+::
+
+ s[0:3]
+
+Note that, we are slicing the string from the index 0 to index 3, 3
+not included.
+
+As we already know, the last element of the string can be accessed
+using ``s[-1]``.
+
+Following is an exercise that you must do.
+
+%%1%% Obtain the sub-string excluding the first and last characters
+from the string s.
+
+Please, pause the video here. Do the exercise(s) and then continue.
+
+::
+
+ s[1:-1]
+
+gives the substring of s, without the first and the last
+characters of s.
+
+::
+
+ s = saturday
+ s[:3]
+
+Now, we just check if that substring is present in the variable
+``week``.
+
+::
+
+ s[:3] in week
+
+Let us now consider the problem of finding out if a given string is
+palindromic or not. First of all, a palindromic string is a string
+that remains same even when it has been reversed.
+
+Let the string given be ``malayalam``.
+
+::
+
+ s = "malayalam"
+
+Now, we need to compare this string with it's reverse.
+
+Again, we will use a technique common to all sequence data-types,
+[::-1]
+
+So, we obtain the reverse of s, by simply saying,
+
+::
+
+ s[::-1]
+
+Now, to check if the string is ``s`` is palindromic, we say
+::
+
+ s == s[::-1]
+
+As, expected, we get ``True``.
+
+Now, if the string we are given is ``Malayalam`` instead of
+``malayalam``, the above comparison would return a False. So, we will
+have to convert the string to all lower case or all upper case, before
+comparing. Python provides methods, ``s.lower`` and ``s.upper`` to
+achieve this.
+
+Let's try it out.
+::
+
+ s = "Malayalam"
+
+ s.upper()
+
+ s
+
+As you can see, s has not changed. It is because, ``upper`` returns a
+new string. It doesn't change the original string.
+
+::
+
+ s.lower()
+
+ s.lower() == s.lower()[::-1]
+
+Following is an exercise that you must do.
+
+%%2%% Check if ``s`` is a valid name of a day of the week. Change the
+solution to this problem, to include forms like, SAT, SATURDAY,
+Saturday and Sat.
+
+Please, pause the video here. Do the exercise and then continue.
+
+::
+
+ s in week
+
+ s.lower()[:3] in week
+
+
+So, as you can see, now we can check for presence of ``s`` in
+``week``, in whichever format it is present -- capitalized, or all
+caps, full name or short form.
+
+We just convert any input string to lower case and then check if it is
+present in the list ``week``.
+
+Now, let us consider another problem. We often encounter e-mail id's
+which have @ and periods replaced with text, something like
+info[at]fossee[dot]in. We now wish to get back proper e-mail
+addresses.
+
+Let's say the variable email has the email address.
+::
+
+ email = "info[at]fossee[dot]in"
+
+Now, we first replace the ``[at]`` with the ``@``, using the replace
+method of strings.
+::
+
+ email = email.replace("[at]", "@")
+ print email
+
+Following is an exercise that you must do.
+
+%%3%% Replace the ``[dot]`` with ``.`` in ``email``
+
+Please, pause the video here. Do the exercise and then continue.
+
+::
+
+ email = email.replace("[dot]", ".")
+ print email
+
+Now, let's look at another interesting problem where we have a list of
+e-mail addresses and we wish to obtain one long string of e-mail
+addresses separated by commas or semi-colons.
+
+::
+
+ email_list = ["info@fossee.in", "enquiries@fossee.in", "help@fossee.in"]
+
+
+Now, if we wish to obtain one long string, separating each of the
+email id by a comma, we use the join operator on ``,``.
+
+::
+
+ email_str = ", ".join(email_list)
+ print email_str
+
+Notice that the email ids are joined by a comma followed by a space.
+
+Following is an exercise that you must do.
+
+%%3%% From the email_str that we generated, change the separator to be
+a semicolon instead of a comma.
+
+Please, pause the video here. Do the exercise and then continue.
+
+::
+
+ email_str = email_str.replace(",", ";")
+
+That brings us to the end of the tutorial.
+
+{{{ show summary slide }}}
+
+In this tutorial, we have learnt how to get substrings, reverse
+strings and a few useful methods, namely upper, lower, replace and
+join.
+
+{{{ 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!
+