diff options
Diffstat (limited to 'day2/session1.tex')
| -rw-r--r-- | day2/session1.tex | 384 |
1 files changed, 242 insertions, 142 deletions
diff --git a/day2/session1.tex b/day2/session1.tex index 18feb02..5fb42e0 100644 --- a/day2/session1.tex +++ b/day2/session1.tex @@ -140,13 +140,13 @@ \begin{itemize} \item \kwrd{int}\\ Any whole number is an \kwrd{int}, no matter what the size! \begin{lstlisting} -In []: a = 13 +In [1]: a = 13 -In []: a = 99999999999999999999 +In [2]: b = 99999999999999999999 \end{lstlisting} \item \kwrd{float} \begin{lstlisting} -In []: fl = 3.141592 +In [3]: fl = 3.141592 \end{lstlisting} \end{itemize} \end{frame} @@ -154,101 +154,254 @@ In []: fl = 3.141592 \begin{frame}[fragile] \frametitle{Complex numbers} \begin{lstlisting} -In []: cplx = 3+4j +In [1]: cplx = 3+4j -In []: abs(cplx) -Out[]: 5.0 +In [2]: abs(cplx) +Out[2]: 5.0 -In []: cplx.imag -Out[]: 4.0 +In [3]: cplx.imag +Out[3]: 4.0 -In []: cplx.real -Out[]: 3.0 +In [4]: cplx.real +Out[4]: 3.0 \end{lstlisting} \end{frame} \subsection{Boolean} -\begin{frame}{Boolean} - \begin{itemize} - \item \kwrd{True} - \item \kwrd{False} - \item \kwrd{not} - \item \kwrd{and} - \item \kwrd{or} - \end{itemize} +\begin{frame}[fragile] + \frametitle{Boolean} + \begin{lstlisting} +In [1]: t = True + +In [2]: f = not t +Out[2]: False + +In [3]: f or t +Out[3]: True + +In [4]: f and t +Out[4]: False + \end{lstlisting} \end{frame} \subsection{Strings} + \begin{frame}[fragile] - \frametitle{String methods} + \frametitle{Strings} Strings were introduced previously, let us now look at them in a little more detail. \begin{lstlisting} -In []: a = 'hello world' +In [1]: w = "hello" + +In [2]: print w[0] + w[2] + w[-1] +Out[2]: hlo + +In [3]: len(w) # guess what +Out[3]: 5 + \end{lstlisting} +\end{frame} + +\begin{frame}[fragile] + \frametitle{Strings \ldots} + \begin{lstlisting} +In [1]: w[0] = 'H' # Can't do that! +-------------------------------------------- +TypeError Traceback (most recent call last) -In []: a.startswith('hell') -Out[]: True +/<ipython console> in <module>() -In []: a.endswith('ld') -Out[]: True +TypeError: 'str' object does not + support item assignment + \end{lstlisting} +\end{frame} + +\begin{frame}[fragile] + \frametitle{String methods} + \begin{lstlisting} +In [1]: a = 'Hello World' +In [2]: a.startswith('Hell') +Out[2]: True + +In [3]: a.endswith('ld') +Out[3]: True + +In [4]: a.upper() +Out[4]: 'HELLO WORLD' + +In [5]: a.lower() +Out[5]: 'hello world' \end{lstlisting} \end{frame} \begin{frame}[fragile] \frametitle{Still with strings} -We saw split() previously. join() is the opposite of split() + \begin{itemize} + \item We saw split() yesterday + \item join() is the opposite of split() + \end{itemize} \begin{lstlisting} -In []: ''.join(['a', 'b', 'c']) -Out[]: 'abc' +In [1]: ''.join(['a', 'b', 'c']) +Out[1]: 'abc' \end{lstlisting} - \begin{block}{Note:} -Strings are immutable.\\ That is string variables cannot be changed. - \end{block} \end{frame} \begin{frame}[fragile] \frametitle{String formatting} \begin{lstlisting} -In []: x, y = 1, 1.234 -In []: 'x is %s, y is %s' %(x, y) -Out[]: 'x is 1, y is 1.234' +In [1]: x, y = 1, 1.234 + +In [2]: 'x is %s, y is %s' %(x, y) +Out[2]: 'x is 1, y is 1.234' \end{lstlisting} - \small -\url{docs.python.org/lib/typesseq-strings.html}\\ +\emphbar{ +\url{http://docs.python.org/library/stdtypes.html}\\ +} \inctime{10} \end{frame} -\section{Relational and logical operators} +\section{Operators} +\begin{frame}[fragile] + \frametitle{Arithematic operators} + \begin{lstlisting} +In [1]: 1786 % 12 +Out[1]: 10 + +In [2]: 3124 * 126789 +Out[2]: 396088836 + +In [3]: a = 3124 * 126789 + +In [4]: big = 1234567891234567890 ** 3 + +In [5]: verybig = big * big * big * big + \end{lstlisting} +\end{frame} + +\begin{frame}[fragile] + \frametitle{Arithematic operators \ldots} + \begin{lstlisting} +In [1]: 17/2 +Out[1]: 8 + +In [2]: 17/2.0 +Out[2]: 8.5 + +In [3]: 17.0/2 +Out[3]: 8.5 + +In [4]: 17.0/8.5 +Out[4]: 2.0 + \end{lstlisting} +\end{frame} + +\begin{frame}[fragile] + \frametitle{String operations} + \begin{lstlisting} +In [1]: s = 'Hello ' + +In [2]: p = 'World' + +In [3]: s + p +Out[3]: 'Hello World' + +In [4]: s * 12 +Out[4]: 'Hello Hello Hello Hello ...' + \end{lstlisting} +\end{frame} + +\begin{frame}[fragile] + \frametitle{String operations \ldots} + \begin{lstlisting} +In [1]: s * s +-------------------------------------------- +TypeError Traceback (most recent call last) + +/<ipython console> in <module>() + +TypeError: can't multiply sequence by + non-int of type 'str' + \end{lstlisting} +\end{frame} + \begin{frame}[fragile] \frametitle{Relational and logical operators} \begin{lstlisting} -In []: pos, zer, neg = 1, 0, -1 -In []: pos == neg -Out[]: False +In [1]: pos, zer, neg = 1, 0, -1 +In [2]: pos == neg +Out[2]: False -In []: pos >= neg -Out[]: True +In [3]: pos >= neg +Out[3]: True -In []: neg < zer < pos -Out[]: True +In [4]: neg < zer < pos +Out[4]: True -In []: pos + neg != zer -Out[]: False +In [5]: pos + neg != zer +Out[5]: False \end{lstlisting} \inctime{5} \end{frame} -\begin{frame} - {A classic problem} +\begin{frame}[fragile] + \frametitle{Built-ins} + \begin{lstlisting} +In [1]: int(17/2.0) +Out[1]: 8 + +In [2]: float(17/2) # Recall +Out[2]: 8.0 + +In [3]: str(17/2.0) +Out[3]: '8.5' + +In [4]: round( 7.5 ) +Out[4]: 8.0 + \end{lstlisting} +\end{frame} + +\begin{frame}[fragile] + \frametitle{Odds and ends} + \begin{itemize} + \item Case sensitive + \item Dynamically typed $\Rightarrow$ need not specify a type + \begin{lstlisting} +In [1]: a = 1 +In [2]: a = 1.1 +In [3]: a = "Now I am a string!" + \end{lstlisting} + \item Comments: + \begin{lstlisting} +In [4]: a = 1 # In-line comments +In [5]: # Comment in a line to itself. +In [6]: a = "# This is not a comment!" + \end{lstlisting} + \end{itemize} + \inctime{15} +\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} + +\section{Simple IO} +\begin{frame}{Simple IO} \begin{block} - {Interchange values} - How to interchange values of two variables? + {Console Input} + \texttt{raw\_input()} waits for user input.\\Prompt string is optional.\\ + All keystrokes are Strings!\\\texttt{int()} converts string to int. \end{block} - \pause - \begin{block}{Note:} - This Python idiom works for all types of variables.\\ -They need not be of the same type! + \begin{block} + {Console output} + \texttt{print} is straight forward. Note the distinction between \texttt{print x} and \texttt{print x,} \end{block} - \inctime{10} \end{frame} \section{Control flow} @@ -279,21 +432,9 @@ else: \end{lstlisting} \end{frame} -\begin{frame}{Simple IO} - \begin{block} - {Console Input} - \texttt{raw\_input()} waits for user input.\\Prompt string is optional.\\ - All keystrokes are Strings!\\\texttt{int()} converts string to int. - \end{block} - \begin{block} - {Console output} - \texttt{print} is straight forward. Note the distinction between \texttt{print x} and \texttt{print x,} - \end{block} -\end{frame} - \subsection{Basic Looping} \begin{frame}[fragile] - \frametitle{\kwrd{while}} + \frametitle{\typ{while}} Example: Fibonacci series \begin{lstlisting} # the sum of two elements @@ -307,7 +448,7 @@ while b < 10: \end{frame} \begin{frame}[fragile] -\frametitle{\kwrd{range()}} +\frametitle{\typ{range()}} \kwrd{range([start,] stop[, step])}\\ \begin{itemize} \item \alert {range() returns a list of integers} @@ -316,7 +457,7 @@ while b < 10: \end{frame} \begin{frame}[fragile] - \frametitle{\kwrd{for}} + \frametitle{\typ{for} \ldots \typ{range()}} Example: print squares of first \typ{n} numbers \begin{lstlisting} In []: for i in range(5): @@ -332,85 +473,44 @@ In []: for i in range(5): \inctime{15} \end{frame} -\section{Lists} -\begin{frame}[fragile] -\frametitle{More List methods} -\begin{lstlisting} -In []: lst = [1,2,3,4,5,6,7,8] -In []: lst.reverse() -In []: lst -Out[]: [8, 7, 6, 5, 4, 3, 2, 1] - -In []: lst.extend([0, -1, -2]) -In []: lst -Out[]: [8, 7, 6, 5, 4, 3, 2, 1, 0, -1] - -In []: lst.remove(0) -In []: lst -Out[]: [8, 7, 6, 5, 4, 3, 2, 1, -1] -\end{lstlisting} -\end{frame} - -\begin{frame}[fragile] -\frametitle{List containership} -\begin{lstlisting} -In []: a = 8 - -In []: a in lst -Out[]: True - -In []: b = 10 -In []: b in lst -Out[]: False - -In []: b not in lst -Out[]: True -\end{lstlisting} -\inctime{10} +\subsection{Exercises} +\begin{frame} + \frametitle{Problem set 1} + \begin{itemize} + \item All the problems can be\\ + solved using \kwrd{if} and \kwrd{while} + \end{itemize} \end{frame} -\section{Tuples} -\begin{frame}[fragile] -\frametitle{Tuples: Immutable lists} -\begin{lstlisting} -In []: tup = (1,2,3,4,5,6,7,8) -In []: tup[0]+tup[3]+tup[-1] -Out[]: 13 -\end{lstlisting} -\begin{block}{Note:} -\begin{itemize} -\item Tuples are immutable - cannot be changed -\item Multiple return values in a function are actually tuples -\item Tuples are working behind the scenes in exchanging values - Tuple Unpacking -\end{itemize} -\end{block} -\inctime{5} +\begin{frame}{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. -\section{Dictionaries} -\begin{frame}[fragile] -\frametitle{Dictionaries} - \alert {lists and tuples: integer indexes :: dictionaries: string indexes} -\begin{lstlisting} -In []: player = {'Mat': 134,'Inn': 233, - 'Runs': 10823, 'Avg': 52.53} - -In []: player['Avg'] -Out[]: 52.530000000000001 -In []: player.keys() -Out[]: ['Runs', 'Inn', 'Avg', 'Mat'] -In []: player.values() -Out[]: [10823, 233, - 52.530000000000001, 134] -\end{lstlisting} \end{frame} -\begin{frame}{Dictionaries} -\begin{itemize} -\item Duplicate keys are not allowed! -\item Dictionaries are iterable through keys. -\end{itemize} -\inctime{5} +\begin{frame}[fragile]{Problem 1.4} + 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 as input.\\ +\pause +\emphbar{When can your code fail?} +\only<2->{\inctime{20}} \end{frame} \end{document} |