Merged heads manually.

2 files changed, 99 insertions, 32 deletions

diff --git a/day1/cheatsheet6.tex b/day1/cheatsheet6.tex
index ee988f6..c4919b0 100755
--- a/day1/cheatsheet6.tex
+++ b/day1/cheatsheet6.tex
@@ -127,4 +127,9 @@ To solve the ODE, we call the \typ{odeint} function with three arguments - the f
 In []: y = odeint(f, y0, t)
 \end{lstlisting}
 Note: To solve a system of ODEs, we need to change the function to return the right hand side of all the equations and the system and the pass the required number of initial conditions to the \typ{odeint} function.
+\section{Links and References}
+\begin{itemize}
+\item Documentation for Numpy and Scipy is available at: \url{http://docs.scipy.org/doc/}
+  \item For "recipes" or worked examples of commonly-done tasks in SciPy explore: \url{http://www.scipy.org/Cookbook/}
+\end{itemize}
 \end{document}
diff --git a/day2/cheatsheet1.tex b/day2/cheatsheet1.tex
index c883ebe..a0d100b 100755
--- a/day2/cheatsheet1.tex
+++ b/day2/cheatsheet1.tex
@@ -26,95 +26,151 @@ showstringspaces=false
 \large{FOSSEE}
 \end{center}
 \section{Data types}
-Complex Numbers
+\subsection{int and float}
+A whole number is a \typ{int} variable.
 \begin{lstlisting}
-In []: c = 3+4j
-In []: abs(c)
+In []: a = 13
+In []: type(a)
+Out[]: <type 'int'>
+In []: b = -2
+In []: type(b)
+Out[]: <type 'int'>
+In []: c = 500000000
+In []: type(c)
+Out[]: <type 'int'>
+\end{lstlisting}
+A number with decimal is a \typ{float}.
+\begin{lstlisting}
+In []: p = 3.141592
+In []: type(p)
+Out[]: <type 'float'>
+\end{lstlisting}
+\subsection{Complex Numbers}
+\begin{lstlisting}
+In []: c = 3+4j  #coeff of j specifies imaginary part
+In []: abs(c) #absolute value of complex number
 Out[]: 5.0
-In []: c.imag
+In []: c.imag #accessing imaginary part of c
 Out[]: 4.0
-In []: c.real
+In []: c.real #accessing real part of c
 Out[]: 3.0
 \end{lstlisting}
-Boolean
+\newpage
+\subsection{Boolean}
 \begin{lstlisting}     
 In []: a = False
 In []: b = True
 In []: c = True
-In []: (a and b) or c
+In []: (a and b) or c #Boolean operations
 Out[]: True
 \end{lstlisting}
-Strings
+\textbf{Note:} Python is case sensitive language, \typ{True} is \typ{bool} type, but \typ{true} would be a variable. and hence following assignment fails:\\
+\typ{In []: a = true}\\
+\subsection{Strings}
   \begin{lstlisting}
-In []: w = "hello"
-In []: print w[0] + w[2] + w[-1]
-Out[]: hlo
-In []: len(w)
+In []: w = "hello" #w is string variable
+In []: print w[1]
+Out[]: e
+In []: print w[-1] #last character of string
+Out[]: o
+  \end{lstlisting}
+\textbf{Note:} For a string variable, individual elements can be accessed using indices.
+  \begin{lstlisting}
+In []: len(w) #function to calculate length of string
 Out[]: 5
 In []: w[0] = 'H' # ERROR: Strings are immutable 
   \end{lstlisting}
-String methods
+\subsection{String methods}
   \begin{lstlisting}
 In []: a = 'Hello World' 
 In []: a.startswith('Hell') # 'a' starts with 'Hell'
+Out[]: True
 In []: a.endswith('ld') # 'a' ends with 'ld'
+Out[]: True
 In []: a.upper() # all characters to upper case
+Out[]: 'HELLO WORLD'
 In []: a.lower() # all characters to lower case
+Out[]: 'hello world'
 In []: ''.join(['a', 'b', 'c'])
 Out[]: 'abc'
   \end{lstlisting}
-String formatting
+\typ{join} function joins all the list member passed as argument with the string it is called upon. In above case it is \typ{empty string}.
+\begin{lstlisting}
+In []: ' '.join(['a','b','c'])
+Out[]: 'a b c'  
+In []: ','.join(['a','b','c'])
+Out[]: 'a,b,c'
+\end{lstlisting}
+\subsection{String formatting}
   \begin{lstlisting}
-In []: x, y = 1, 1.234
+In []: x, y = 1, 1.234 #initializing two variables
 In []: 'x is %s, y is %s' %(x, y)
 Out[]: 'x is 1, y is 1.234'
   \end{lstlisting}
-Arithmetic Operators
+\textbf{Note:} \typ{\%s} used in above fomatting specifies \typ{'str'} representation of variables. One can also try:\\
+\typ{\%d} for \typ{int} representation\\
+\typ{\%f} for \typ{float} representation
+\begin{lstlisting}
+In []: 'x is %f, y is %f' %(x, y)
+Out[]: 'x is 1.000000, y is 1.234000'
+
+In []: 'x is %d, y is %d' %(x, y)
+Out[]: 'x is 1, y is 1'
+\end{lstlisting}
+\subsection{Arithmetic Operators}
   \begin{lstlisting}
 In []: 45 % 2 # Modulo operator
 Out[]: 1
-In []: 1234567891234567890 ** 3 # Power
+In []: 5 ** 3 # Power
+Out[]: 125
 In []: a = 5
-In []: a += 1
+In []: a += 1 #increment by 1, translates to a = a + 1
 In []: a *= 2
   \end{lstlisting}
-String Operations
+\subsection{String Operations}
 \begin{lstlisting}
 In []: s = 'Hello'
 In []: p = 'World'
-In []: s + p 
+In []: s + p  #concatenating two strings
 Out[]: 'HelloWorld'
-In []: s * 4
+In []: s * 4  #repeating string for given num of times
 Out[]: 'HelloHelloHelloHello'
 \end{lstlisting}
-Relational and Logical Operators
+\subsection{Relational and Logical Operators}
 \begin{lstlisting}
-In []: p, z, n = 1, 0, -1
-In []: p == n
+In []: p, z, n = 1, 0, -1 #initializing three variables
+In []: p == n  #equivalency check
 Out[]: False
-In []: p >= n
+In []: p >= n 
 Out[]: True
-In []: n < z < p
+In []: n < z < p #finding largest number among three
 Out[]: True
 In []: p + n != z
 Out[]: False
 \end{lstlisting}
-Built-ins
+\subsection{Built-ins}
 \begin{lstlisting}
-In []: int(17 / 2.0)
+In []: int(17 / 2.0) #converts arguments to integer
 Out[]: 8
-In []: float(17 / 2)
+In []: float(17 / 2) #argument is already integer(17 / 2 = 8)
 Out[]: 8.0
-In []: str(17 / 2.0)
+In []: str(17 / 2.0) #converts to string
 Out[]: '8.5'
-In []: round( 7.5 )
+In []: round( 7.5 ) 
 Out[]: 8.0
 \end{lstlisting}
-Console Input
+\subsection{Console Input}
 \begin{lstlisting}
 In []: a = raw_input('Enter a value: ')
 Enter a value: 5
 \end{lstlisting}
+\textbf{Note:} \typ{raw_input} always returns string representation of user input and hence:
+\begin{lstlisting}
+In []: type(a)
+Out[]: <type 'str'>
+\end{lstlisting}
+To get integer or floating point of this input, one has to perform type conversion:\\
+\typ{In []: b = int(a)}
 \section{Conditionals}
 \typ{if}
 \begin{lstlisting}
@@ -133,4 +189,10 @@ Ternary Operator
 In []: a = raw_input('Enter number(Q to quit):')
 In []: num = int(a) if a != 'Q' else 0
 \end{lstlisting}
+Above statement can be read as ``num is int of a, if a is not equal to 'Q', otherwise 0 ``
+\section{Links and References}
+\begin{itemize}
+  \item Reference manual to describe the standard libraries  that are distributed with Python is available at \url{http://docs.python.org/library/} 
+  \item To read more on strings refer to: \\ \url{http://docs.python.org/library/stdtypes.html#string-methods}
+\end{itemize}
 \end{document}