Workshop materials: comparison day2/session4.tex

equal deleted inserted replaced

-:9664eddee075
+:8a4a1e5aec85
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 % Title page
-\title[]{Debugging and \\Test Driven Approach}
+\title[Python Development]{Python Development}
 \author[FOSSEE] {FOSSEE}
 \institute[IIT Bombay] {Department of Aerospace Engineering\\IIT Bombay}
-\date[] {11, October 2009}
+\date[] {1 November, 2009\\Day 2, Session 3}
-\date[] % (optional)
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %\pgfdeclareimage[height=0.75cm]{iitblogo}{iitblogo}
 %\logo{\pgfuseimage{iitblogo}}
 \begin{frame}
 \maketitle
 \end{frame}
+\section{Tests: Getting started}
+\begin{frame}[fragile]
+\frametitle{gcd revisited!}
+\begin{itemize}
+\item Open gcd.py
+\end{itemize}
+\begin{lstlisting}
+def gcd(a, b):
+if a % b == 0:
+return b
+return gcd(b, a%b)
+print gcd(15, 65)
+print gcd(16, 76)
+\end{lstlisting}
+\begin{itemize}
+\item python gcd.py
+\end{itemize}
+\end{frame}
+\begin{frame}[fragile]
+\frametitle{Find lcm using our gcd module}
+\begin{itemize}
+\item Open lcm.py
+\item $lcm = \frac{a*b}{gcd(a,b)}$
+\end{itemize}
+\begin{lstlisting}
+from gcd import gcd
+def lcm(a, b):
+return (a * b) / gcd(a, b)
+print lcm(14, 56)
+\end{lstlisting}
+\begin{itemize}
+\item python lcm.py
+\end{itemize}
+\begin{lstlisting}
+5
+4
+56
+\end{lstlisting}
+\end{frame}
+\begin{frame}[fragile]
+\frametitle{Writing stand-alone module}
+Edit gcd.py file to:
+\begin{lstlisting}
+def gcd(a, b):
+if a % b == 0:
+return b
+return gcd(b, a%b)
+if __name__ == "__main__":
+print gcd(15, 65)
+print gcd(16, 76)
+\end{lstlisting}
+\begin{itemize}
+\item python gcd.py
+\item python lcm.py
+\end{itemize}
+\end{frame}
+\begin{frame}[fragile]
+\frametitle{More use of main}
+For automating tests.
+\begin{lstlisting}
+if __name__ == '__main__':
+for line in open('numbers.txt'):
+numbers = line.split()
+x = int(numbers[0])
+y = int(numbers[1])
+result = (int(numbers[2]))
+assert gcd(x, y) == result
+\end{lstlisting}
+\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{Debugging}
 \subsection{Errors and Exceptions}
 \begin{frame}[fragile]
 \frametitle{Errors}
 \begin{lstlisting}
->>> while True print 'Hello world'
+In []: while True print 'Hello world'
 \end{lstlisting}
 \pause
 \begin{lstlisting}
 File "<stdin>", line 1, in ?
 while True print 'Hello world'
 \end{frame}
 \begin{frame}[fragile]
 \frametitle{Exceptions}
 \begin{lstlisting}
->>> print spam
+In []: print spam
 \end{lstlisting}
 \pause
 \begin{lstlisting}
 Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 \end{frame}
 \begin{frame}[fragile]
 \frametitle{Exceptions}
 \begin{lstlisting}
->>> 1 / 0
+In []: 1 / 0
 \end{lstlisting}
 \pause
 \begin{lstlisting}
 Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 ZeroDivisionError: integer division
 or modulo by zero
 \end{lstlisting}
 \end{frame}
+\begin{frame}[fragile]
+\frametitle{Handling Exceptions}
+Python uses \typ{try} and \typ{except} clause.
+%%Revisiting the raw\_input
+\begin{lstlisting}
+a = raw_input('Enter number(Q to quit):')
+try:
+num = int(a)
+print num
+except:
+if a == 'Q':
+print 'Exiting...'
+else:
+print 'Wrong input!'
+\end{lstlisting}
+\end{frame}
+%% \begin{frame}[fragile]
+%%   \frametitle{Solving it with \typ{try} and \typ{except}}
+%% \vspace{-0.2in}
+%%   \begin{lstlisting}
+%% highest = 0
+%% for record in open('sslc1.txt'):
+%%     fields = record.split(';')
+%%     try:
+%%         total = 0
+%%         for score_str in fields[3:8]:
+%%             score = int(score_str)
+%%             total += score
+%%         if total > highest:
+%%             highest = total
+%%     except:
+%%         pass
+%% print highest
+%%   \end{lstlisting}
+%% \end{frame}
 \subsection{Strategy}
 \begin{frame}[fragile]
 \frametitle{Debugging effectively}
 \begin{itemize}
 \item \typ{print} based strategy
 \begin{frame}[fragile]
 \frametitle{Debugging in IPython}
 \small
 \begin{lstlisting}
-In [1]: import mymodule
+In []: import mymodule
-In [2]: mymodule.test()
+In []: mymodule.test()
 ---------------------------------------------
 NameError   Traceback (most recent call last)
 <ipython console> in <module>()
 mymodule.py in test()
 1 def test():
 ----> 2     print spam
 NameError: global name 'spam' is not defined
-In [3]: %debug
+In []: %debug
 > mymodule.py(2)test()
 0     print spam
 ipdb>
 \end{lstlisting}
 \inctime{15}
 \subsection{Exercise}
 \begin{frame}[fragile]
 \frametitle{Debugging: Exercise}
 \small
 \begin{lstlisting}
-import keyword
+science = {}
-f = open('/path/to/file')
+for record in open('sslc1.txt'):
-freq = {}
+fields = record.split(';')
-for line in f:
+region_code = fields[0].strip()
-words = line.split()
-for word in words:
+score_str = fields[6].strip()
-key = word.strip(',.!;?()[]: ')
+score = int(score_str) if score_str != 'AA'
-if keyword.iskeyword(key):
+else 0
-value = freq[key]
-freq[key] = value + 1
+if score > 90:
+science[region_code] += 1
-print freq
+pie(science.values(), labels=science.keys())
+savefig('science.png')
 \end{lstlisting}
 \inctime{10}
 \end{frame}
 %% \begin{frame}
 %%     \end{itemize}
 %% \end{frame}
 \section{Test Driven Approach}
 \begin{frame}
-\frametitle{Need of Testing!}
+\frametitle{Need for Testing!}
 \begin{itemize}
 \item Quality
 \item Regression
 \item Documentation
 \end{frame}
 \begin{frame}[fragile]
 \frametitle{Test for the palindrome: palindrome.py}
 \begin{lstlisting}
-from plaindrome import is_palindrome
 def test_function_normal_words():
 input = "noon"
 assert is_palindrome(input) == True
+if __name__ == "main'':
+test_function_normal_words()
 \end{lstlisting}
 \end{frame}
 \begin{frame}[fragile]
 \frametitle{Running the tests.}
 \begin{lstlisting}
-$ nosetests test.py
+$ nosetests palindrome.py
 .
 ----------------------------------------------
 Ran 1 test in 0.001s
 OK
 input = "Noon"
 assert is_palindrome(input) == True
 \end{lstlisting}
 \vspace*{0.25in}
 Check\\
-\PythonCode{$ nosetests test.py} \\
+\PythonCode{$ nosetests palindrome.py} \\
 \begin{block}{Task}
 Tweak the code to pass this test.
 \end{block}
 \end{frame}
 %
 %\inctime{15}
 %\end{frame}
 %
-\begin{frame}[fragile]
+%% \begin{frame}[fragile]
-\frametitle{Exercise}
+%%     \frametitle{Exercise}
-Based on Euclid's algorithm:
+%%     Based on Euclid's algorithm:
-\begin{center}
+%%     \begin{center}
-$gcd(a,b)=gcd(b,b\%a)$
+%%     $gcd(a,b)=gcd(b,b\%a)$
-\end{center}
+%%     \end{center}
-gcd function can be written as:
+%%     gcd function can be written as:
-\begin{lstlisting}
+%%     \begin{lstlisting}
-def gcd(a, b):
+%%     def gcd(a, b):
-if a%b == 0: return b
+%%       if a%b == 0: return b
-return gcd(b, a%b)
+%%       return gcd(b, a%b)
-\end{lstlisting}
+%%     \end{lstlisting}
-\vspace*{-0.15in}
+%%     \vspace*{-0.15in}
-\begin{block}{Task}
+%%     \begin{block}{Task}
-\begin{itemize}
+%%       \begin{itemize}
-\item Write at least
+%%       \item Write at least
-two tests for above mentioned function.
+%%         two tests for above mentioned function.
-\item Write a non recursive implementation
+%%       \item Write a non recursive implementation
-of gcd(), and test it using already
+%%       of gcd(), and test it using already
-written tests.
+%%       written tests.
-\end{itemize}
+%%       \end{itemize}
-\end{block}
+%%     \end{block}
-\inctime{15}
+%% \inctime{15}
-\end{frame}
+%% \end{frame}
 \begin{frame}
-\frametitle{We have learned}
+\frametitle{Summary}
+We have coverd:
 \begin{itemize}
 \item Following and Resolving Error Messages.
 \item Exceptions.
+\item Handling exceptions
 \item Approach for Debugging.
 \item Writting and running tests.
 \end{itemize}
 \end{frame}

changeset 263	8a4a1e5aec85
parent 256	a06196a05043
child 288	c4e25269a86c