227 \begin{frame}{So what did we learn here??}

   227 \begin{frame}{New Concepts}

   230     \item \alert{\kwrd{for}}

   230     \item \typ{for}

   286 \section{File Handling}

   286 \begin{frame}[fragile]

   287 \begin{frame}[fragile]

   287 \frametitle{Reading pendulum.txt}

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

   288 \begin{itemize}

   289 \begin{lstlisting}

   289   \item We now wish to repeat the plot using the values from a file

   290 In []: f = open('dummyfile')

   290   \item Given a file containing L vs. T values 

   291 

   291   \item Column1 - L; Column2 - T  

   292 In []: for line in f:

   292   \item Read the file

   293     ...:     print line

   293   \item Plot points for L vs. $T^2$ 

   294     ...:  

   294 \end{itemize}

   295 \end{lstlisting}

   295 \end{frame}

   296 \inctime{5}

   296 

   297 \end{frame}

   297 \begin{frame}[fragile]

   298 

   298 \frametitle{Reading pendulum.txt}

   299 \section{Strings}

   299 \begin{lstlisting}

   300 \begin{frame}{Strings}

   300 In []: L = []

   301 In []: T = []

   302 In []: for line in open('pendulum.txt'):

   303   ....     points = line.split()

   304   ....     L.append(float(points[0]))

   305   ....     T.append(float(points[1]))

   306 \end{lstlisting}

   307 \begin{itemize}

   308 \item We now have two lists L and T

   309 \item Now, Repeat previous steps for plotting

   310 \end{itemize}

   311 \end{frame}

   312 

   313 \begin{frame}[fragile]

   314 \frametitle{Plotting from pendulum.txt}

   315 \begin{lstlisting}

   316 In []: TSq = []

   317 

   318 In []: for t in T:

   319  ....:     TSq.append(t*t)

   320 

   321 In []: plot(L, TSq, '.')

   322 \end{lstlisting}

   323 \end{frame}

   324 

   325 \begin{frame}{New Concepts}

   326   \begin{itemize}

   327     \item File handling

   328     \item Strings

   329     \item Data-type conversion

   330   \end{itemize}

   331 \end{frame}

   332 

   333 \begin{frame}[fragile]

   334   \frametitle{Reading files \ldots}

   335 \typ{In []: for line in open('pendulum.txt'):}

   336 \begin{itemize}

   337 \item opening file `pendulum.txt'

   338 \item iterating through file using variable \typ{line}

   339 \item \typ{line} is a \kwrd{string} variable

   340 \end{itemize}

   341 \end{frame}

   342 

   343 \begin{frame}[fragile]

   344 \frametitle{Strings}

   302 \end{frame}

   346 \begin{lstlisting}

   303 

   347 ' This is a string '  

   304 \begin{frame}[fragile]\frametitle{Strings and \typ{split()}}

   348 " This too! "

   349 """ This one too! """

   350 ''' And one more! '''

   351 \end{lstlisting}

   352 \end{frame}

   353 

   354 \begin{frame}[fragile]

   355 \frametitle{Strings and \typ{split()}}

   306 In []: a = 'hello world'

   357 In []: line = 'hello world'

   311 Now try this:

   362 This is what happens with \typ{line}

   313 In []: b = 'KD, MCS, PC, SC, SV'

   364 In []: line = '1.2000e-01 7.4252e-01'

   314 

   365 

   315 In []: b.split(',')

   366 In []: line.split()

   316 Out[]: ['KD', 'MCS', 'PC', 'SC', 'SV']

   367 Out[]: ['1.2000e-01', '7.4252e-01']

   318 \inctime{5}

   369 \end{frame}

   319 \end{frame}

   370 

   371 \begin{frame}[fragile]

   372 \frametitle{Getting floats from strings}

   373   \begin{lstlisting}

   374 In []: type(points[0])

   375 Out[]: <type 'str'>

   376   \end{lstlisting}

   377 But, we need floating point numbers

   378   \begin{lstlisting}

   379 In []: t = float(point[0])

   380 

   381 In []: type(t)

   382 Out[]: <type 'float'>

   383   \end{lstlisting}

   384 \end{frame}

   385 

   386 \begin{frame}[fragile]

   387 \begin{figure}

   388 \includegraphics[width=3.5in]{data/L-Tsq.png}

   389 \end{figure}

   390 \vspace{-0.2in}

   391 Coming up - \alert{Least Square Fit \ldots}

   392 \end{frame}

   393 

   394 

   395