5 % Copyright (c) 2005-2008, Prabhu Ramachandran

     5 % Copyright (c) 2005-2009, Prabhu Ramachandran

    36     basicstyle=\ttfamily,

    36     basicstyle=\ttfamily\bfseries,

    81 \date[] {25, July 2009}

    81 \date[] {10, October 2009}

   253 \subsection{Getting Started}

   115 \subsection{Exercises on Control flow}

   254 

   255 \begin{frame}[fragile]{At the prompt, type the following}

   256    \begin{lstlisting}

   257 >>> print 'Hello Python' 

   258 >>> print 3124 * 126789

   259 >>> 1786 % 12

   260 >>> 3124 * 126789

   261 >>> a = 3124 * 126789

   262 >>> big = 12345678901234567890 ** 3

   263 >>> verybig = big * big * big * big 

   264 >>> 12345**6, 12345**67, 12345**678

   265   \end{lstlisting}

   266 \end{frame}

   267 

   268 \begin{frame}[fragile]{At the prompt, type the following}

   269    \begin{lstlisting}

   270 >>> s = 'Hello '

   271 >>> p = 'World'

   272 >>> s + p 

   273 >>> s * 12 

   274 >>> s * s

   275 >>> s + p * 12, (s + p)* 12

   276 >>> s * 12 + p * 12

   277 >>> 12 * s 

   278     \end{lstlisting}

   279 \end{frame}

   280 

   281 \begin{frame}[fragile]{At the prompt, type the following}

   282   \begin{lstlisting}

   283 >>> 17/2

   284 >>> 17/2.0

   285 >>> 17.0/2

   286 >>> 17.0/8.5

   287 >>> int(17/2.0)

   288 >>> float(17/2)

   289 >>> str(17/2.0)

   290 >>> round( 7.5 )

   291   \end{lstlisting}

   292   \begin{block}{Mini exercise}

   293 	Round a float to the nearest integer, using \texttt{int()}?

   294   \end{block}

   295 \end{frame}

   296 

   297 \begin{frame}{Midi exercises}

   298   \begin{center}

   299     \begin{itemize}

   300       \item What does this do?

   301       \item \texttt{round(amount * 10) /10.0 }

   302     \end{itemize}

   303   \end{center}

   304 \end{frame}

   305 

   306 \begin{frame}{More exercises?}

   307   \begin{center}

   308     \begin{block}{Round sums}

   309       How to round a number to the nearest  5 paise?\\

   310       \begin{description}

   311         \item[Remember] 17.23 $\rightarrow$ 17.25,\\ while 17.22 $\rightarrow$ 17.20\\

   312       \end{description}

   313       How to round a number to the nearest 20 paise?

   314     \end{block}

   315   \end{center}

   316 \end{frame}

   317 

   318 \begin{frame}[fragile] {A question of good style}

   319   \begin{lstlisting}

   320     amount = 12.68

   321     denom = 0.05

   322     nCoins = round(amount/denom)

   323     rAmount = nCoins * denom

   324   \end{lstlisting}

   325   \pause

   326   \begin{block}{Style Rule \#1}

   327     Naming is 80\% of programming

   328   \end{block}

   329 \end{frame}

   330 

   331 

   332 \begin{frame}[fragile]

   333   \frametitle{Odds and ends}

   334   \begin{itemize}

   335     \item Case sensitive

   336     \item Dynamically typed $\Rightarrow$ need not specify a type

   337       \begin{lstlisting}

   338 a = 1

   339 a = 1.1

   340 a = "Now I am a string!"

   341       \end{lstlisting}

   342     \item Comments:

   343       \begin{lstlisting}

   344 a = 1  # In-line comments

   345 # Comment in a line to itself.

   346 a = "# This is not a comment!"

   347       \end{lstlisting}

   348   \end{itemize}

   349   \inctime{15}

   350 \end{frame}

   351 

   352 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   353 % TIME: 15 m, running 30m

   354 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   355 

   356 \subsection{Data types}

   357 \begin{frame}

   358   \frametitle{Basic types}

   359   \begin{itemize}

   360     \item numbers: float, int, long, complex

   361     \item strings

   362     \item boolean

   363   \end{itemize}

   364   \begin{block}{Also to be discussed later}

   365     tuples, lists, dictionaries, functions, objects\ldots

   366   \end{block}

   367 \end{frame}

   368 

   369 \begin{frame}[fragile]

   370   \frametitle{Numbers}

   371   \vspace*{-0.25in}

   372   \begin{lstlisting}

   373 >>> a = 1 # Int.

   374 >>> l = 1000000L # Long

   375 >>> e = 1.01325e5 # float

   376 >>> f = 3.14159 # float

   377 >>> c = 1+1j # Complex!

   378 >>> print f*c/a

   379 (3.14159+3.14159j)

   380 >>> print c.real, c.imag

   381 1.0 1.0

   382 >>> abs(c)

   383 1.4142135623730951

   384 >>> abs( 8 - 9.5 )

   385 1.5

   386   \end{lstlisting}

   387 \end{frame}

   388 

   389 \begin{frame}[fragile]

   390   \frametitle{Boolean}

   391   \begin{lstlisting}

   392 >>> t = True

   393 >>> f = not t

   394 False

   395 >>> f or t

   396 True

   397 >>> f and t

   398 False

   399   \end{lstlisting}

   400   \begin{block}{Try:}

   401   NOT True\\

   402   not TRUE

   403   \end{block}

   404 \end{frame}

   405 

   406 \begin{frame}[fragile]

   407   \frametitle{Relational and logical operators}

   408   \begin{lstlisting}

   409 >>> a, b, c = -1, 0, 1

   410 >>> a == b

   411 False

   412 >>> a <= b 

   413 True

   414 >>> a + b != c

   415 True

   416 >>> a < b < c

   417 True

   418 >>> c >= a + b

   419 True

   420   \end{lstlisting}

   421 \end{frame}

   422 

   423 \begin{frame}[fragile]

   424   \frametitle{Strings}

   425   \begin{lstlisting}

   426 s = 'this is a string'

   427 s = 'This one has "quotes" inside!'

   428 s = "I have 'single-quotes' inside!"

   429 l = "A string spanning many lines\

   430 one more line\

   431 yet another"

   432 t = """A triple quoted string does

   433 not need to be escaped at the end and 

   434 "can have nested quotes" etc."""

   435   \end{lstlisting}

   436 \end{frame}

   437 

   438 \begin{frame}[fragile]

   439   \frametitle{More Strings}

   440   \vspace*{-0.2in}

   441   \begin{lstlisting}

   442 >>> w = "hello"    

   443 >>> print w[0] + w[2] + w[-1]

   444 hlo

   445 >>> len(w) # guess what

   446 5

   447 >>> s = u'Unicode strings!'

   448 >>> # Raw strings (note the leading 'r')

   449 ... r_s = r'A string $\alpha \nu$'

   450   \end{lstlisting}

   451 \pause

   452   \begin{lstlisting}

   453 >>> w[0] = 'H' # Can't do that!

   454 Traceback (most recent call last):

   455   File "<stdin>", line 1, in ?

   456 TypeError: object does not support item assignment

   457   \end{lstlisting}

   458 \end{frame}

   459 

   460 \begin{frame}

   461   \frametitle{Let us switch to IPython}

   462   Why?

   463   \begin{block}

   464     {Better help (and a lot more)}

   465     Tab completion\\

   466     ?\\

   467     .?\\

   468     object.function?

   469   \end{block}

   470 \end{frame}

   471 

   472 \begin{frame}[fragile]

   473   \frametitle{More on strings}

   474   \begin{lstlisting}

   475 In [1]: a = 'hello world'

   476 In [2]: a.startswith('hell')

   477 Out[2]: True

   478 In [3]: a.endswith('ld')

   479 Out[3]: True

   480 In [4]: a.upper()

   481 Out[4]: 'HELLO WORLD'

   482 In [5]: a.upper().lower()

   483 Out[5]: 'hello world'

   484   \end{lstlisting}

   485 \end{frame}

   486 

   487 \begin{frame}[fragile]{Still with strings}

   488   \begin{lstlisting}

   489 In [6]: a.split()

   490 Out[6]: ['hello', 'world']

   491 In [7]: ''.join(['a', 'b', 'c'])

   492 Out[7]: 'abc'

   493 In [8] 'd' in ''.join( 'a', 'b', 'c')

   494 Out[8]: False

   495   \end{lstlisting}

   496   \begin{block}{Try:}

   497     \texttt{a.split( 'o' )}\\

   498     \texttt{'x'.join( a.split( 'o' ) )}

   499   \end{block}

   500 \end{frame}

   501 

   502 \begin{frame}[fragile]{Surprise! strings!!}

   503   \begin{lstlisting}

   504 In [11]: x, y = 1, 1.2

   505 In [12]: 'x is %s, y is %s' %(x, y)

   506 Out[12]: 'x is 1, y is 1.234'

   507   \end{lstlisting}

   508   \begin{block}{Try:}

   509     \texttt{'x is \%d, y is \%f' \%(x, y) }\\

   510     \texttt{'x is \%3d, y is \%4.2f' \%(x, y) }

   511   \end{block}

   512   \small

   513 \url{docs.python.org/lib/typesseq-strings.html}\\

   514 \end{frame}

   515 

   516 \begin{frame}

   517   {Interlude}

   518   \begin{block}

   519     {A classic problem}

   520     How to interchange values of two variables? Please note that the type of either variable is unknown and it is not necessary that both be of the same type even!

   521   \end{block}

   522   \inctime{30}

   523 \end{frame}

   524 

   525 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   526 % TIME: 25 m+ Interlude break 5 mins, running 60m 

   527 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   528 

   529 \subsection{Control flow}

   530 \begin{frame}

   531   \frametitle{Control flow constructs}  

   532   \begin{itemize}

   533   \item \kwrd{if/elif/else}: branching

   534   \item \kwrd{while}: looping

   535   \item \kwrd{for}: iterating 

   536   \item \kwrd{break, continue}: modify loop 

   537   \item \kwrd{pass}: syntactic filler

   538   \end{itemize}

   539 \end{frame}

   540 

   541 \begin{frame}[fragile]

   542   \frametitle{Basic conditional flow}

   543   \begin{lstlisting}

   544 In [21]: a = 7

   545 In [22]: b = 8

   546 In [23]: if a > b:

   547    ....:    print 'Hello'

   548    ....: else:

   549    ....:     print 'World'

   550    ....:

   551    ....:

   552 World

   553   \end{lstlisting}

   554   Let us switch to creating a file

   555 \end{frame}

   556 

   557 \begin{frame}

   558   {Creating python files}

   559   \begin{itemize}

   560     \item aka scripts

   561     \item use your editor

   562     \item Note that white space is the way to specify blocks!

   563     \item extension \typ{.py}

   564     \item run with \texttt{python hello.py} at the command line

   565     \item in IPython\ldots

   566   \end{itemize}

   567 \end{frame}

   568 

   569 \begin{frame}[fragile]

   570   \frametitle{\typ{If...elif...else} example}

   571 \begin{lstlisting}

   572 x = int(raw_input("Enter an integer:"))

   573 if x < 0:

   574      print 'Be positive!'

   575 elif x == 0:

   576      print 'Zero'

   577 elif x == 1:

   578      print 'Single'

   579 else:

   580      print 'More'

   581 \end{lstlisting}

   582 \end{frame}

   583 

   584 \begin{frame}{Simple IO}

   585   \begin{block}

   586     {Console Input}

   587     \texttt{raw\_input(}) waits for user input.\\Prompt string is optional.\\

   588     All keystrokes are Strings!\\\texttt{int()} converts string to int.

   589   \end{block}

   590   \begin{block}

   591     {Console output}

   592     \texttt{print} is straight forward. Major point to remember is the distinction between \texttt{print x} and \texttt{print x,}

   593   \end{block}

   594 \end{frame}

   595 

   596 \begin{frame}[fragile]

   597   \frametitle{Basic looping}

   598   \begin{lstlisting}

   599 # Fibonacci series:

   600 # the sum of two elements

   601 # defines the next

   602 a, b = 0, 1

   603 while b < 10:

   604     print b,

   605     a, b = b, a + b

   606  

   607 \end{lstlisting}

   608 \typ{1 1 2 3 5 8}\\  

   609 \alert{Recall it is easy to write infinite loops with \kwrd{while}}

   610   \inctime{20}

   611 \end{frame}

   612 

   613 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   614 % TIME: 20 m, running 80m 

   615 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   616 

   633   \item If the number is even, divide by 2; if the number is odd multiply by 3 and add 1.

   132   \item If the number is even, divide by 2; if the number is odd, multiply by 3 and add 1.

   663 \only<2->{\inctime{25}}

   162 \only<2->{\inctime{20}}

   664 \end{frame}

   163 \end{frame}

   665 

   164 

   666 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   165 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   667 % TIME: 25 m, running 105m 

   166 % TIME: 20 m, running 20m 

   753   \inctime{15} 

   252   \inctime{10} 

   754 \end{frame}

   253 \end{frame}

   755 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   254 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   756 % TIME: 15 m, running 120m 

   255 % TIME: 10 m, running 30m 

   785   \inctime{30}

   284   \inctime{25}

   786 \end{frame}

   285 \end{frame}

   787 

   286 

   788 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   287 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   789 % TIME: 30 m, running 150m 

   288 % TIME: 25 m, running 55m 

   821 [2, 3, 4]

   320 [2, 3]

   846 [1, 3]

   345 [1, 2]

   874 \end{frame}

   373 \inctime{10}

   374 \end{frame}

   375 

   376 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   377 % TIME: 10 m, running 65m 

   378 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   883 >>> a.append(['x', 1]) 

   387 >>> a.append(['x', 1])

   906 \end{frame}

   410   \inctime{5}

   411 \end{frame}

   412 

   413 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   414 % TIME: 5 m, running 70m 

   415 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   917 TypeError: object does not support item

   426 TypeError: object does not support item assignment

   918            assignment

   924 

   432 \inctime{5}

   925 \end{frame}

   433 \end{frame}

   434 

   435 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   436 % TIME: 5 m, running 75m 

   437 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   986 \inctime{20}

   498 \inctime{10}

   987 \end{frame}

   499 \end{frame}

   988 

   500 

   989 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   501 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   990 % TIME: 20 m, running 170m 

   502 % TIME: 10 m, running 85m 

   991 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   992 

   993 \begin{frame}

   994   {Problem set 3}

   995   As you can guess, idea is to use \kwrd{for}!

   996 \end{frame}

   997 

   998 \begin{frame}{Problem 3.1}

   999   Which of the earlier problems is simpler when we use \kwrd{for} instead of \kwrd{while}? 

  1000 \end{frame}

  1001 

  1002 \begin{frame}{Problem 3.2}

  1003   Given an empty chessboard and one Bishop placed in any square, say (r, c), generate the list of all squares the Bishop could move to.

  1004 \end{frame}

  1005 

  1006 \begin{frame}[fragile]

  1007   \frametitle{Problem 3.3}

  1008 

  1009   Given two real numbers \typ{a, b}, and an integer \typ{N}, write a

  1010   function named \typ{linspace( a, b, N)} that returns an ordered list

  1011   of \typ{N} points starting with \typ{a} and ending in \typ{b} and

  1012   equally spaced.\\

  1013 

  1014   For example, \typ{linspace(0, 5, 11)}, should return, \\

  1015 \begin{lstlisting}

  1016 [ 0.0 ,  0.5,  1.0 ,  1.5,  2.0 ,  2.5,  

  1017   3.0 ,  3.5,  4.0 ,  4.5,  5.0 ]

  1018 \end{lstlisting}

  1019 \end{frame}

  1020 

  1021 \begin{frame}[fragile]

  1022   \frametitle{Problem 3.4a (optional)}

  1023 

  1024 Use the \typ{linspace} function and generate a list of N tuples of the form\\

  1025 \typ{[($x_1$,f($x_1$)),($x_2$,f($x_2$)),\ldots,($x_N$,f($x_N$))]}\\for the following functions,\begin{itemize}

  1026   \item \typ{f(x) = sin(x)}

  1027   \item \typ{f(x) = sin(x) + sin(10*x)}.

  1028 \end{itemize}

  1029 \end{frame}

  1030 

  1031 \begin{frame}[fragile]

  1032   \frametitle{Problem 3.4b (optional)}

  1033 

  1034   Using the tuples generated earlier, determine the intervals where the roots of the functions lie.

  1035 

  1036   \inctime{15}

  1037 \end{frame}

  1038 

  1039 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  1040 % TIME: 15 m, running 185m 

  1041 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  1042 

  1043 \subsection{IO}

  1044 

  1045 \begin{frame}[fragile]

  1046   \frametitle{Simple tokenizing and parsing}

  1047   \begin{lstlisting}

  1048 s = """The quick brown fox jumped

  1049        over the lazy dog"""

  1050 for word in s.split():

  1051     print word.capitalize()

  1052   \end{lstlisting}

  1053 \end{frame}

  1054 

  1055 \begin{frame}[fragile]

  1056   \frametitle{Problem 4.1}

  1057   Given a string like, ``1, 3-7, 12, 15, 18-21'', produce the list \\

  1058   \begin{lstlisting}

  1059     [1,3,4,5,6,7,12,15,18,19,20,21]

  1060   \end{lstlisting}

  1061 \end{frame}

  1062 

  1063 \begin{frame}[fragile]

  1064   \frametitle{File handling}

  1065 \begin{lstlisting}

  1066 >>> f = open('/path/to/file_name')

  1067 >>> data = f.read() # Read entire file.

  1068 >>> line = f.readline() # Read one line.

  1069 >>> f.close() # close the file.

  1070 \end{lstlisting}

  1071 Writing files

  1072 \begin{lstlisting}

  1073 >>> f = open('/path/to/file_name', 'w')

  1074 >>> f.write('hello world\n')

  1075 >>> f.close()

  1076 \end{lstlisting}

  1077 \begin{itemize}

  1078     \item Everything read or written is a string

  1079 \end{itemize}

  1080 \emphbar{Try \typ{file?} for more help}

  1081 \end{frame}

  1082 

  1083 \begin{frame}[fragile]

  1084     \frametitle{File and \kwrd{for}}

  1085 \begin{lstlisting}

  1086 >>> f = open('/path/to/file_name')

  1087 >>> for line in f:

  1088 ...     print line

  1089 ...

  1090 \end{lstlisting}

  1091 \end{frame}

  1092 

  1093 \begin{frame}{Problem 4.2}

  1094     The given file has lakhs of records in the form:\\

  1095     \typ{RGN;ID;NAME;MARK1;\ldots;MARK5;TOTAL;PFW}\\

  1096     Some entries may be empty.  Read the data from this file and print the

  1097     name of the student with the maximum total marks.

  1098 \end{frame}

  1099 

  1100 \begin{frame}{Problem 4.3}

  1101     For the same data file compute the average marks in different

  1102     subjects, the student with the maximum mark in each subject and also

  1103     the standard deviation of the marks.  Do this efficiently.

  1104 

  1105     \inctime{20}

  1106 \end{frame}

  1107 

  1108 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  1109 % TIME: 20 m, running 205m 

  1110 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  1111 

  1112 \subsection{Modules}

  1113 

  1114 \begin{frame}[fragile]

  1115     {Modules}

  1116 \begin{lstlisting}

  1117 >>> sqrt(2)

  1118 Traceback (most recent call last):

  1119   File "<stdin>", line 1, in <module>

  1120 NameError: name 'sqrt' is not defined

  1121 >>> import math        

  1122 >>> math.sqrt(2)

  1123 1.4142135623730951

  1124 \end{lstlisting}

  1125 \end{frame}

  1126 

  1127 \begin{frame}[fragile]

  1128     {Modules}

  1129   \begin{itemize}

  1130     \item The \kwrd{import} keyword ``loads'' a module

  1131     \item One can also use:

  1132       \begin{lstlisting}

  1133 >>> from math import sqrt

  1134 >>> from math import *

  1135       \end{lstlisting}    

  1136     \item What is the difference?

  1137     \item \alert{Use the later only in interactive mode}

  1138     \end{itemize}

  1139   \emphbar{Package hierarchies}

  1140       \begin{lstlisting}

  1141 >>> from os.path import exists

  1142       \end{lstlisting}

  1143 \end{frame}

  1144 

  1145 \begin{frame}

  1146   \frametitle{Modules: Standard library}

  1147   \begin{itemize}

  1148   \item Very powerful, ``Batteries included''

  1149   \item Some standard modules:

  1150     \begin{itemize}

  1151     \item Math: \typ{math}, \typ{random}

  1152     \item Internet access: \typ{urllib2}, \typ{smtplib}

  1153     \item System, Command line arguments: \typ{sys}

  1154     \item Operating system interface: \typ{os}

  1155     \item Regular expressions: \typ{re}

  1156     \item Compression: \typ{gzip}, \typ{zipfile}, and \typ{tarfile}

  1157     \item And a whole lot more!

  1158     \end{itemize}

  1159   \item Check out the Python Library reference:

  1160     \url{http://docs.python.org/library/}

  1161   \end{itemize}

  1162 \end{frame}

  1163 

  1164 \begin{frame}[fragile]

  1165     {Modules of special interest}

  1166     \begin{description}[matplotlibfor2d]

  1167 

  1168         \item[\typ{numpy}] Efficient, powerful numeric arrays

  1169 

  1170         \item[\typ{matplotlib}] Easy, interactive, 2D plotting

  1171 

  1172         \item[\typ{scipy}] statistics, optimization, integration, linear

  1173             algebra, Fourier transforms, signal and image processing,

  1174             genetic algorithms, ODE solvers, special functions, and more

  1175 

  1176         \item[Mayavi] Easy, interactive, 3D plotting

  1177 

  1178     \end{description}

  1179 \end{frame}

  1180 

  1181 \begin{frame}[fragile]

  1182     {Creating your own modules}

  1183   \begin{itemize}

  1184   \item Define variables, functions and classes in a file with a

  1185     \typ{.py} extension

  1186   \item This file becomes a module!

  1187   \item Accessible when in the current directory

  1188   \item Use \typ{cd} in IPython to change directory

  1189 

  1190   \item Naming your module

  1191       \end{itemize}

  1192 \end{frame}

  1193 

  1194 \begin{frame}[fragile]

  1195   \frametitle{Modules: example}

  1196   \begin{lstlisting}

  1197 # --- arith.py ---

  1198 def gcd(a, b):

  1199     if a%b == 0: return b

  1200     return gcd(b, a%b)

  1201 def lcm(a, b):

  1202     return a*b/gcd(a, b)

  1203 # ------------------

  1204 >>> import arith

  1205 >>> arith.gcd(26, 65)

  1206 13

  1207 >>> arith.lcm(26, 65)

  1208 130

  1209   \end{lstlisting}

  1210 \end{frame}

  1211 

  1212 \begin{frame}[fragile]

  1213   \frametitle{Problem 5.1}

  1214 

  1215   Put all the functions you have written so far as part of the problems

  1216   into one module called \typ{iitb.py} and use this module from IPython.

  1217 

  1218 \inctime{20}

  1219 \end{frame}

  1220 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  1221 % TIME: 20 m, running 225m 

  1228   \end{frame}

   509 \end{frame}

  1229 

   510 

  1230   \begin{frame}

  1231     {Tomorrow}

  1232     \begin{itemize}

  1233       \item Plotting: 2D, 3D

  1234       \item NumPy, SciPy

  1235       \item Dictionary, Set

  1236       \item Debugging

  1237       \item Testing

  1238       \item \ldots

  1239     \end{itemize}

  1240     11:30--13:00 Discussion of answers to problems OPTIONAL

  1241   \end{frame}