--- a/manipulating-strings.rst Wed Oct 06 15:08:52 2010 +0530
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,179 +0,0 @@
-========
- Script
-========
-
-{{{ show the welcome slide }}}
-
-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
-
-#[punch: reversed returns an iterator. should we still teach it?]
-
-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. We 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 string 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]``.
-
-%%1%% Pause the video here and obtain the sub-string excluding the
-first and last characters from the string.
-
-::
-
- s[1:-1]
-
-gives the a substring of s, without the first and the last
-characters.
-
-::
-
- 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
-
- s.lower()
-
- s.lower() == s.lower()[::-1]
-
-Note that these methods, do not change the original string, but return
-a new string.
-
-a%% %% Pause the video here, and finish the problem of checking if
-``s`` is a valid name of a day of the week and then resume the
-video. Change the solution to this problem, to include forms like,
-SAT, SATURDAY, Saturday and Sat.
-
-::
-
- s.lower()[:3] in week
-
-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
-
-%%1%% Pause the video here and replace the ``[dot]`` with ``.`` and then
-resume the video.
-
-::
-
- email = email.replace("[dot]", ".")
- print email
-
-
-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 and replace.
-
-Thank You!