--- a/day2/cheatsheet2.tex Tue Nov 24 11:00:52 2009 +0530
+++ b/day2/cheatsheet2.tex Wed Nov 25 12:11:03 2009 +0530
@@ -201,7 +201,57 @@
\end{lstlisting}
\textbf{Note:} elements cant be changed!
\section{Dictionaries}
-statistics section?
+Dictionaries are data structures that provide key-value mappings. They are similar to lists except that instead of the values having integer indexes, they have keys or strings as indexes.\\
+A simple dictionary can be created by:
+\begin{lstlisting}
+In []: player = {'Mat': 134,'Inn': 233,
+ 'Runs': 10823, 'Avg': 52.53}
+\end{lstlisting}
+For above case, value on left of ':' is key and value on right is corresponding value. To retrieve value related to key 'Avg'
+\begin{lstlisting}
+In []: player['Avg']
+Out[]: 52.530000000000001
+\end{lstlisting}
+\subsection{Element operations}
+\begin{lstlisting}
+In []: player['Name'] = 'Rahul Dravid' #Adds new key-value pair.
+In []: player
+Out[]:
+{'Avg': 52.530000000000001,
+ 'Inn': 233,
+ 'Mat': 134,
+ 'Name': 'Rahul Dravid',
+ 'Runs': 10823}
+In []: player.pop('Mat') # removing particular key-value pair
+Out[]: 134
+In [21]: player
+Out[21]: {'Avg': 52.530000000000001, 'Inn': 233,
+ 'Name': 'Rahul Dravid', 'Runs': 10823}
+\end{lstlisting}
+\textbf{Note:} Duplicate keys are overwritten!\\
+\begin{lstlisting}
+In []: player['Name'] = 'Dravid'
+In []: player
+Out[23]: {'Avg': 52.530000000000001, 'Inn': 233,
+ 'Name': 'Dravid', 'Runs': 10823}
+\end{lstlisting}
+\subsection{containership}
+\begin{lstlisting}
+In []: 'Inn' in player
+Out[]: True
+In []: 'Econ' in player
+Out[]: False
+\end{lstlisting}
+\textbf{Note:} Containership is always checked on 'keys' of dictionary but not 'values'.\\
+\subsection{Methods}
+\begin{lstlisting}
+In []: player.keys() # returns list of all keys
+Out[]: ['Runs', 'Inn', 'Avg', 'Mat']
+
+In []: player.values() # returns list of all values.
+Out[]: [10823, 233,
+ 52.530000000000001, 134]
+\end{lstlisting}
\section{Sets}
are an unordered collection of unique elements.\\
Creation: