diff options
Diffstat (limited to 'slides/basic_python/io_files_parsing.tex')
| -rw-r--r-- | slides/basic_python/io_files_parsing.tex | 69 |
1 files changed, 35 insertions, 34 deletions
diff --git a/slides/basic_python/io_files_parsing.tex b/slides/basic_python/io_files_parsing.tex index cb46cbe..f766f1c 100644 --- a/slides/basic_python/io_files_parsing.tex +++ b/slides/basic_python/io_files_parsing.tex @@ -3,9 +3,9 @@ \begin{frame}[fragile] \frametitle{Printing} \begin{lstlisting} - In[]: a = "This is a string" - In[]: a - In[]: print a + In[]: a = "This is a string" + In[]: a + In[]: print a \end{lstlisting} \begin{itemize} \item Both \texttt{a}, and \texttt{print a} are showing the value @@ -15,19 +15,20 @@ \item In a script, it has no effect. \end{itemize} \begin{lstlisting} - In[]: b = "A line \n New line" - In[]: b - In[]: print b + In[]: b = "A line \n New line" + In[]: b + In[]: print b \end{lstlisting} \end{frame} \begin{frame}[fragile] \frametitle{String formatting} + \small \begin{lstlisting} In[]: x = 1.5 - In[]: y = 2 - In[]: z = "zed" - In[]: print "x is %2.1f y is %d z is %s" %(x, y, z) + In[]: y = 2 + In[]: z = "zed" + In[]: print "x is %2.1f y is %d z is %s" %(x, y, z) \end{lstlisting} \end{frame} @@ -42,7 +43,7 @@ In[]: print "Hello" In[]: print "World" - In[]: print "Hello", + In[]: print "Hello", In[]: print "World" \end{lstlisting} \begin{itemize} @@ -55,7 +56,7 @@ \begin{frame}[fragile] \frametitle{\texttt{raw\_input}} \begin{lstlisting} - In[]: ip = raw_input() + In[]: ip = raw_input() \end{lstlisting} \begin{itemize} \item The cursor is blinking; waiting for input @@ -69,17 +70,17 @@ \begin{frame}[fragile] \frametitle{\texttt{raw\_input} \ldots} \begin{lstlisting} - In[]: c = raw_input() - In[]: 5.6 + In[]: c = raw_input() + 5.6 In[]: c - In[]: type(c) + In[]: type(c) \end{lstlisting} \begin{itemize} \item \alert{\texttt{raw\_input} always takes a string} \end{itemize} \begin{lstlisting} - In[]: name = raw_input("Please enter your name: ") - George + In[]: name = raw_input("Enter your name: ") + Enter your name: George \end{lstlisting} \begin{itemize} \item \texttt{raw\_input} can display a prompt string for the user @@ -126,7 +127,7 @@ \item Close the file, when done; Also, if you want to read again \end{itemize} \begin{lstlisting} - In[]: f.close() + In[]: f.close() In[]: f \end{lstlisting} \end{frame} @@ -157,7 +158,7 @@ \end{lstlisting} \begin{itemize} \item File with records like the one above is given - \item Each record has fields separated by ; + \item Each record has fields separated by \verb+;+ \item region code; roll number; name; \item marks --- $1^{st}$ L; $2^{nd}$ L; math; science; social; total \item pass/fail indicated by P/F; W if withheld and else empty @@ -171,8 +172,8 @@ \begin{frame}[fragile] \frametitle{Tokenization} \begin{lstlisting} - In[]: line = "parse this string" - In[]: line.split() + In[]: line = "parse this string" + In[]: line.split() \end{lstlisting} \begin{itemize} \item Original string is split on white-space (if no argument) @@ -180,7 +181,7 @@ \item It can be given an argument to split on that argrument \end{itemize} \begin{lstlisting} - In[]: record = "A;015163;JOSEPH RAJ S;083;042;47;AA;72;244;;;" + In[]: record = "A;015163;JOSEPH RAJ S;083;042;47;AA;72;244;;;" In[]: record.split(';') \end{lstlisting} \end{frame} @@ -207,9 +208,9 @@ \item We need numbers to perform math operations \end{itemize} \begin{lstlisting} - In[]: mark_str = "1.25" - In[]: mark = int(mark_str) - In[]: type(mark_str) + In[]: mark_str = "1.25" + In[]: mark = int(mark_str) + In[]: type(mark_str) In[]: type(mark) \end{lstlisting} \begin{itemize} @@ -220,20 +221,20 @@ \begin{frame}[fragile] \frametitle{File parsing -- Solution} \begin{lstlisting} - In[]: math_B = [] # empty list to store marks + In[]: math_B = [] # empty list to store marks In[]: for line in open("sslc1.txt"): - ....: fields = line.split(";") + ....: fields = line.split(";") - ....: reg_code = fields[0] - ....: reg_code_clean = reg_code.strip() + ....: reg_code = fields[0] + ....: reg_code_clean = reg_code.strip() - ....: math_mark_str = fields[5] - ....: math_mark = float(math_mark_str) + ....: math_mark_str = fields[5] + ....: math_mark = float(math_mark_str) - ....: if reg_code == "B": - ....: math_B.append(math_mark) + ....: if reg_code == "B": + ....: math_B.append(math_mark) - In[]: math_B_mean = sum(math_B) / len(math_B) - In[]: math_B_mean + In[]: math_B_mean = sum(math_B) / len(math_B) + In[]: math_B_mean \end{lstlisting} \end{frame} |