--- a/day2/session2.tex Fri Nov 06 17:56:22 2009 +0530
+++ b/day2/session2.tex Fri Nov 06 18:33:08 2009 +0530
@@ -1,8 +1,8 @@
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%Tutorial slides on Python.
%
-% Author: Prabhu Ramachandran <prabhu at aero.iitb.ac.in>
-% Copyright (c) 2005-2009, Prabhu Ramachandran
+% Author: FOSSEE
+% Copyright (c) 2009, FOSSEE, IIT Bombay
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\documentclass[14pt,compress]{beamer}
@@ -78,7 +78,7 @@
\author[FOSSEE Team] {The FOSSEE Group}
\institute[IIT Bombay] {Department of Aerospace Engineering\\IIT Bombay}
-\date[] {1, November 2009\\Day 2, Session 2}
+\date[] {8 November, 2009\\Day 2, Session 2}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%\pgfdeclareimage[height=0.75cm]{iitmlogo}{iitmlogo}
@@ -123,13 +123,113 @@
% You might wish to add the option [pausesections]
\end{frame}
+\section{Control flow}
+\subsection{Basic Looping}
+\begin{frame}[fragile]
+ \frametitle{\typ{while}}
+Example: Fibonacci series
+ \begin{lstlisting}
+# the sum of two elements
+# defines the next
+In []: a, b = 0, 1
+In []: while b < 10:
+ ...: print b,
+ ...: a, b = b, a + b
+ ...:
+ ...:
+\end{lstlisting}
+\typ{1 1 2 3 5 8}\\
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\typ{range()}}
+\kwrd{range([start,] stop[, step])}\\
+\begin{itemize}
+ \item range() returns a list of integers
+ \item The \emph{start} and the \emph{step} arguments are optional
+ \item \emph{stop} argument is not included in the list
+\end{itemize}
+\vspace*{.5in}
+\begin{itemize}
+ \item \alert{Anything within \typ{[]} is optional}
+ \begin{itemize}
+ \item Nothing to do with Python.
+ \end{itemize}
+\end{itemize}
+
+\end{frame}
+
+\begin{frame}[fragile]
+ \frametitle{\typ{for} \ldots \typ{range()}}
+Example: print squares of first \typ{n} numbers
+ \begin{lstlisting}
+In []: for i in range(5):
+ ....: print i, i * i
+ ....:
+ ....:
+0 0
+1 1
+2 4
+3 9
+4 16
+\end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile]
+ \frametitle{\typ{for} \ldots \typ{range()}}
+Example: print squares of odd numbers from 3 to 9
+ \begin{lstlisting}
+In []: for i in range(3, 10, 2):
+ ....: print i, i * i
+ ....:
+ ....:
+3 9
+5 25
+7 49
+9 81
+\end{lstlisting}
+\inctime{5}
+\end{frame}
+
+\subsection{Exercises}
+
+\begin{frame}{Problem set 1: Problem 1.1}
+ Write a program that displays all three digit numbers that are equal to the sum of the cubes of their digits. That is, print numbers $abc$ that have the property $abc = a^3 + b^3 + c^3$\\
+\vspace*{0.2in}
+\emphbar{These are called $Armstrong$ numbers.}
+\end{frame}
+
+\begin{frame}{Problem 1.2 - Collatz sequence}
+\begin{enumerate}
+ \item Start with an arbitrary (positive) integer.
+ \item If the number is even, divide by 2; if the number is odd, multiply by 3 and add 1.
+ \item Repeat the procedure with the new number.
+ \item It appears that for all starting values there is a cycle of 4, 2, 1 at which the procedure loops.
+\end{enumerate}
+ Write a program that accepts the starting value and prints out the Collatz sequence.
+\end{frame}
+
+\begin{frame}[fragile]{Problem 1.3}
+ Write a program that prints the following pyramid on the screen.
+ \begin{lstlisting}
+1
+2 2
+3 3 3
+4 4 4 4
+ \end{lstlisting}
+The number of lines must be obtained from the user.\\
+\pause
+\emphbar{When can your code fail?}
+\inctime{5}
+\end{frame}
+
\section{Data structures}
\subsection{Lists}
\begin{frame}[fragile]
\frametitle{Lists}
\begin{block}{We already know that}
\begin{lstlisting}
-num = [1, 2, 3, 4, 5, 6, 7, 8]
+num = [1, 2, 3, 4]
\end{lstlisting}
\centerline{is a list}
\end{block}
@@ -138,29 +238,76 @@
\begin{frame}[fragile]
\frametitle{Lists: methods}
\begin{lstlisting}
+In []: num = [1, 2, 3, 4]
+
+In []: num.append([9, 10, 11])
+
+In []: num
+Out[]: [1, 2, 3, 4, [9, 10, 11]]
+ \end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile]
+ \frametitle{Lists: methods}
+ \begin{lstlisting}
+In []: num = [1, 2, 3, 4]
+
+In []: num.extend([5, 6, 7])
+In []: num
+Out[]: [1, 2, 3, 4, 5, 6, 7]
+
In []: num.reverse()
In []: num
-Out[]: [8, 7, 6, 5, 4, 3, 2, 1]
+Out[]: [7, 6, 5, 4, 3, 2, 1]
-In []: num.extend([0, -1, -2])
+In []: num.remove(6)
In []: num
-Out[]: [8, 7, 6, 5, 4, 3, 2, 1, 0, -1]
+ \end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile]
+ \frametitle{Lists: slicing}
+ \begin{itemize}
+ \item \typ{list[initial:final]}
+ \end{itemize}
+\begin{lstlisting}
+In []: a = [1, 2, 3, 4, 5]
+
+In []: a[1:3]
+Out[]: [2, 3]
+
+In []: a[1:-1]
+Out[]: [2, 3, 4]
-In []: num.remove(0)
-In []: num
-Out[]: [8, 7, 6, 5, 4, 3, 2, 1, -1]
- \end{lstlisting}
+In []: a[:3]
+Out[]: [1, 2, 3]
+\end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile]
+ \frametitle{Lists: slicing}
+ \begin{itemize}
+ \item \typ{list[initial:final:step]}
+ \end{itemize}
+\begin{lstlisting}
+In []: a[1:-1:2]
+Out[]: [2, 4]
+
+In []: a[::2]
+Out[]: [1, 3, 5]
+
+In []: a[-1::-1]
+Out[]: [5, 4, 3, 2, 1]
+\end{lstlisting}
\end{frame}
\begin{frame}[fragile]
\frametitle{List containership}
\begin{lstlisting}
-In []: a = 8
-
-In []: a in num
+In []: 4 in num
Out[]: True
-In []: b = 10
+In []: b = 15
In []: b in num
Out[]: False
@@ -174,9 +321,14 @@
\frametitle{Tuples: Immutable lists}
\begin{lstlisting}
In []: t = (1, 2, 3, 4, 5, 6, 7, 8)
+
In []: t[0] + t[3] + t[-1]
Out[]: 13
+
+# Try the following!
+In []: t[4] = 7
\end{lstlisting}
+\pause
\begin{block}{Note:}
\begin{itemize}
\item Tuples are immutable - cannot be changed
@@ -200,7 +352,7 @@
\subsection{Dictionaries}
\begin{frame}[fragile]
- \frametitle{Dictionaries: Recall}
+ \frametitle{Dictionaries: recall}
\begin{lstlisting}
In []: player = {'Mat': 134,'Inn': 233,
'Runs': 10823, 'Avg': 52.53}
@@ -214,6 +366,28 @@
\end{block}
\end{frame}
+\begin{frame}[fragile]
+ \frametitle{Dictionaries: containership}
+ \begin{lstlisting}
+In []: 'Inn' in player
+Out[]: True
+
+In []: 'Econ' in player
+Out[]: False
+ \end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile]
+ \frametitle{Dictionaries: methods}
+ \begin{lstlisting}
+In []: player.keys()
+Out[]: ['Runs', 'Inn', 'Avg', 'Mat']
+
+In []: player.values()
+Out[]: [10823, 233, 52.530000000000001, 134]
+ \end{lstlisting}
+\end{frame}
+
\begin{frame} {Problem Set 2.1: Problem 2.1.1}
You are given date strings of the form ``29, Jul 2009'', or ``4 January 2008''. In other words a number, a string and another number, with a comma sometimes separating the items.\\Write a function that takes such a string and returns a tuple (yyyy, mm, dd) where all three elements are ints.
\end{frame}
@@ -228,32 +402,47 @@
\item >, >=, <, <=, in, \ldots
\end{itemize}
\begin{lstlisting}
->>> f10 = set([1,2,3,5,8])
->>> p10 = set([2,3,5,7])
->>> f10|p10
-set([1, 2, 3, 5, 7, 8])
->>> f10&p10
-set([2, 3, 5])
->>> f10-p10
-set([8, 1])
+
+In []: f10 = set([1,2,3,5,8])
+
+In []: p10 = set([2,3,5,7])
+
+In []: f10 | p10
+Out[]: set([1, 2, 3, 5, 7, 8])
\end{lstlisting}
\end{frame}
\begin{frame}[fragile]
- \frametitle{Set}
+ \frametitle{Set \ldots}
\begin{lstlisting}
->>> p10-f10, f10^p10
-set([7]), set([1, 7, 8])
->>> set([2,3]) < p10
-True
->>> set([2,3]) <= p10
-True
->>> 2 in p10
-True
->>> 4 in p10
-False
->>> len(f10)
-5
+In []: f10 & p10
+Out[]: set([2, 3, 5])
+
+In []: f10 - p10
+Out[]: set([1, 8])
+
+In []: p10 - f10, f10 ^ p10
+Out[]: (set([7]), set([1, 7, 8]))
+
+In []: set([2,3]) < p10
+Out[]: True
+\end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile]
+ \frametitle{Set \ldots}
+ \begin{lstlisting}
+In []: set([2,3]) <= p10
+Out[]: True
+
+In []: 2 in p10
+Out[]: True
+
+In []: 4 in p10
+Out[]: False
+
+In []: len(f10)
+Out[]: 5
\end{lstlisting}
\end{frame}
@@ -261,7 +450,14 @@
\frametitle{Problem set 2.2}
\begin{description}
\item[2.2.1] Given a dictionary of the names of students and their marks, identify how many duplicate marks are there? and what are these?
- \item[2.2.2] Given a string of the form ``4-7, 9, 12, 15'' find the missing numbers in the given range.
+\end{description}
+\inctime{15}
+\end{frame}
+
+\begin{frame}
+ \frametitle{Problem set 2.2}
+ \begin{description}
+ \item[2.2.2] Given a list of words, find all the anagrams in the list
\end{description}
\inctime{15}
\end{frame}
@@ -294,6 +490,19 @@
\end{frame}
\begin{frame}[fragile]
+ \frametitle {What does this function do?}
+ \begin{lstlisting}
+def what( n ):
+ if n < 0: n = -n
+ while n > 0:
+ if n % 2 == 1:
+ return False
+ n /= 10
+ return True
+ \end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile]
{What does this function do?}
\begin{lstlisting}
def what( n ):
@@ -304,219 +513,13 @@
\end{lstlisting}
\end{frame}
-\subsection{Default arguments}
-\begin{frame}[fragile]
- \frametitle{Functions: default arguments}
- \small
- \begin{lstlisting}
-def ask_ok(prompt, complaint='Yes or no!'):
- while True:
- ok = raw_input(prompt)
- if ok in ('y', 'ye', 'yes'):
- return True
- if ok in ('n', 'no', 'nop',
- 'nope'):
- return False
- print complaint
-
-ask_ok('?')
-ask_ok('?', '[Y/N]')
- \end{lstlisting}
-\end{frame}
-
-\subsection{Built-in functions}
\begin{frame}
- {Before writing a function}
- \begin{itemize}
- \item Variety of builtin functions are available
- \item \typ{abs, any, all, len, max, min}
- \item \typ{pow, range, sum, type}
- \item Refer here:
- \url{http://docs.python.org/library/functions.html}
- \end{itemize}
- \inctime{10}
-\end{frame}
-
-\subsection{Exercises}
-\begin{frame}{Problem set 3: Problem 3.1}
- Write a function to return the gcd of two numbers.
-\end{frame}
-
-\begin{frame}{Problem 3.2}
-Write a program to print all primitive pythagorean triads (a, b, c) where a, b are in the range 1---100 \\
-A pythagorean triad $(a,b,c)$ has the property $a^2 + b^2 = c^2$.\\By primitive we mean triads that do not `depend' on others. For example, (4,3,5) is a variant of (3,4,5) and hence is not primitive. And (10,24,26) is easily derived from (5,12,13) and is also not primitive.
-\end{frame}
-
-\begin{frame}{Problem 3.3}
- Write a program that generates a list of all four digit numbers that have all their digits even and are perfect squares.\newline\\\emph{For example, the output should include 6400 but not 8100 (one digit is odd) or 4248 (not a perfect square).}
-\inctime{15}
-\end{frame}
-
-\section{Modules}
-\begin{frame}[fragile]
- {Modules}
-\begin{lstlisting}
->>> sqrt(2)
-Traceback (most recent call last):
- File "<stdin>", line 1, in <module>
-NameError: name 'sqrt' is not defined
->>> import math
->>> math.sqrt(2)
-1.4142135623730951
-\end{lstlisting}
-\end{frame}
-
-\begin{frame}[fragile]
- {Modules}
- \begin{itemize}
- \item The \kwrd{import} keyword ``loads'' a module
- \item One can also use:
- \begin{lstlisting}
->>> from math import sqrt
->>> from math import *
- \end{lstlisting}
- \item What is the difference?
- \item \alert{Use the latter only in interactive mode}
- \end{itemize}
- \emphbar{Package hierarchies}
- \begin{lstlisting}
->>> from os.path import exists
- \end{lstlisting}
-\end{frame}
-
-\begin{frame}
- \frametitle{Modules: Standard library}
+ \frametitle{What did we learn?}
\begin{itemize}
- \item Very powerful, ``Batteries included''
- \item Some standard modules:
- \begin{itemize}
- \item Math: \typ{math}, \typ{random}
- \item Internet access: \typ{urllib2}, \typ{smtplib}
- \item System, Command line arguments: \typ{sys}
- \item Operating system interface: \typ{os}
- \item Regular expressions: \typ{re}
- \item Compression: \typ{gzip}, \typ{zipfile}, and \typ{tarfile}
- \item And a whole lot more!
- \end{itemize}
- \item Check out the Python Library reference:
- \url{http://docs.python.org/library/}
- \end{itemize}
-\inctime{5}
-\end{frame}
-
-\section{Coding Style}
-\begin{frame}{Readability and Consistency}
- \begin{itemize}
- \item Readability Counts!\\Code is read more often than its written.
- \item Consistency!
- \item Know when to be inconsistent.
- \end{itemize}
-\end{frame}
-
-\begin{frame}[fragile] \frametitle{A question of good style}
- \begin{lstlisting}
- amount = 12.68
- denom = 0.05
- nCoins = round(amount/denom)
- rAmount = nCoins * denom
- \end{lstlisting}
- \pause
- \begin{block}{Style Rule \#1}
- Naming is 80\% of programming
- \end{block}
-\end{frame}
-
-\begin{frame}[fragile]
- \frametitle{Code Layout}
- \begin{itemize}
- \item Indentation
- \item Tabs or Spaces??
- \item Maximum Line Length
- \item Blank Lines
- \item Encodings
- \end{itemize}
-\end{frame}
-
-\begin{frame}{Whitespaces in Expressions}
- \begin{itemize}
- \item When to use extraneous whitespaces??
- \item When to avoid extra whitespaces??
- \item Use one statement per line
- \end{itemize}
-\end{frame}
-
-\begin{frame}{Comments}
- \begin{itemize}
- \item No comments better than contradicting comments
- \item Block comments
- \item Inline comments
- \end{itemize}
-\end{frame}
-
-\begin{frame}{Docstrings}
- \begin{itemize}
- \item When to write docstrings?
- \item Ending the docstrings
- \item One liner docstrings
- \end{itemize}
-More information at PEP8: http://www.python.org/dev/peps/pep-0008/
-\inctime{5}
-\end{frame}
-
-\section{Objects}
-\begin{frame}{Objects in general}
- \begin{itemize}
- \item What is an Object? (Types and classes)
- \item identity
- \item type
- \item method
- \end{itemize}
-\end{frame}
-
-\begin{frame}{Almost everything is an Object!}
- \begin{itemize}
- \item \typ{list}
- \item \typ{tuple}
- \item \typ{string}
- \item \typ{dictionary}
- \item \typ{function}
- \item Of course, user defined class objects!
- \end{itemize}
-\end {frame}
-
-\begin{frame}{Using Objects}
- \begin{itemize}
- \item Creating Objects: Initialization
- \item Object Manipulation: Object methods and ``.'' operator
+ \item Loops: \kwrd{while}, \kwrd{for}
+ \item Advanced Data structures
+ \item Functions
\end{itemize}
\end{frame}
-\begin{frame}[fragile]
- \frametitle{Objects provide consistency}
- \small
- \begin{lstlisting}
-for element in (1, 2, 3):
- print element
-for key in {'one':1, 'two':2}:
- print key
-for char in "123":
- print char
-for line in open("myfile.txt"):
- print line
-for line in urllib2.urlopen('http://site.com'):
- print line
- \end{lstlisting}
-\inctime{10}
-\end{frame}
-
-\begin{frame}
- \frametitle{What did we learn?}
- \begin{itemize}
- \item Lists, Tuples, Dictionaries, Sets: creation and manipulation
- \item More about functions
- \item Coding style
- \item Objects: creation and manipulation
- \end{itemize}
-\end{frame}
-
-\end{document}
+\end{document}
\ No newline at end of file