Workshop materials: comparison day2/session1.tex

equal deleted inserted replaced

-:ab9192cfe870
+:523f788d2147
 \begin{frame}[fragile]
 \frametitle{Examples of \num}
 \begin{lstlisting}
 # Simple array math example
->>> from numpy import *
+>>> import numpy as np
->>> a = array([1,2,3,4])
+>>> a = np.array([1,2,3,4])
->>> b = array([2,3,4,5])
+>>> b = np.arange(2,6)
+>>> b
+array([2,3,4,5])
 >>> a*2 + b + 1 # Basic math!
 array([5, 8, 11, 14])
+\end{lstlisting}
+\end{frame}
+\begin{frame}[fragile]
+\frametitle{Examples of \num}
+\begin{lstlisting}
 # Pi and e are defined.
->>> x = linspace(0.0, 10.0, 1000)
+>>> x = np.linspace(0.0, 10.0, 1000)
->>> x *= 2*pi/10 # inplace.
+>>> x *= 2*np.pi/10 # inplace.
 # apply functions to array.
->>> y = sin(x)
+>>> y = np.sin(x)
+>>> z = np.exp(y)
 \end{lstlisting}
 \inctime{5}
 \end{frame}
 \begin{frame}
 \begin{frame}[fragile]
 \frametitle{More examples of \num}
 \vspace*{-8pt}
 \begin{lstlisting}
->>> x = array([1., 2, 3, 4])
+>>> x = np.array([1., 2, 3, 4])
->>> size(x)
+>>> np.size(x)
 4
 >>> x.dtype # What is a.dtype?
 dtype('float64')
 >>> x.shape
 (4,)
->>> print rank(x), x.itemsize
+>>> print np.rank(x), x.itemsize
 1 8
 >>> x[0] = 10
 >>> print x[0], x[-1]
 10.0 4.0
 \end{lstlisting}
 \end{frame}
 \begin{frame}[fragile]
 \frametitle{Multi-dimensional arrays}
 \begin{lstlisting}
->>> a = array([[ 0, 1, 2, 3],
+>>> a = np.array([[ 0, 1, 2, 3],
 ...            [10,11,12,13]])
 >>> a.shape # (rows, columns)
 (2, 4)
 # Accessing and setting values
 >>> a[1,3]
 13
 >>> a[1,3] = -1
 >>> a[1] # The second row
 array([10,11,12,-1])
+\end{lstlisting}
-\end{lstlisting}
+\end{frame}
-\end{frame}
 \begin{frame}[fragile]
 \frametitle{Array math}
 \begin{itemize}
 \item Basic \alert{elementwise} math (given two arrays \typ{a, b}):
 \typ{+, -, *, /, \%}
-\item Inplace operators: \typ{a += b}, or \typ{add(a, b, a)} etc.
+\item Inplace operators: \typ{a += b}, or \typ{np.add(a, b, a)} etc.
-\item \typ{sum(x, axis=0)},
+\item \typ{np.sum(x, axis=0)},
-\typ{product(x, axis=0)},
+\typ{np.product(x, axis=0)},
-\typ{dot(a, bp)}
+\typ{np.dot(a, bp)}
 \end{itemize}
+\begin{lstlisting}
+>>> b=np.array([[0,2,4,2],[1,2,3,4]])
+>>> np.add(a,b,a)
+>>> np.sum(x,axis=1)
+\end{lstlisting}
 \end{frame}
 \begin{frame}[fragile]
 \frametitle{Array math cont.}
 \begin{itemize}
-\item Logical operations: \typ{equal (==)}, \typ{not\_equal (!=)},
+\item Logical operations: \typ{np.equal (==)}, \typ{np.not\_equal (!=)},
-\typ{less (<)}, \typ{greater (>)} etc.
+\typ{np.less (<)}, \typ{np.greater (>)} etc.
-\item Trig and other functions: \typ{sin(x),}
+\item Trig and other functions: \typ{np.sin(x),}
-\typ{arcsin(x), sinh(x),}
+\typ{np.arcsin(x), np.sinh(x),}
-\typ{exp(x), sqrt(x)} etc.
+\typ{np.exp(x), np.sqrt(x)} etc.
 \end{itemize}
+\begin{lstlisting}
+>>> np.greater(a,4)
+>>> np.sqrt(a)
+\end{lstlisting}
 \inctime{10}
 \end{frame}
 \subsection{Array Creation \& Slicing, Striding Arrays}
 \begin{frame}[fragile]
 \frametitle{Array creation functions}
-\begin {block}{\typ{array(object, dtype=None, ...)}}
-\begin{lstlisting}
->>> array( [2,3,4] )
-array([2, 3, 4])
-\end{lstlisting}
-\end {block}
-\begin{block}{\typ{linspace(start, stop, num=50, ...)}}
-\begin{lstlisting}
->>> linspace( 0, 2, 4 )
-array([0.,0.6666667,1.3333333,2.])
-\end{lstlisting}
-\end{block}
 \begin{itemize}
-\item also try \typ{arange} command
+\item {\typ{np.array(object,dtype=None,...)}
+\begin{lstlisting}
+>>> np.array([2,3,4])
+array([2, 3, 4])
+\end{lstlisting}
+\item \typ{np.linspace(start,stop,...)}
+\begin{lstlisting}
+>>> np.linspace(0, 2, 4)
+array([0.,0.6666667,1.3333333,2.])
+\end{lstlisting}
+\item Also try \typ{np.arange}
 \end{itemize}
 \end{frame}
 \begin{frame}[fragile]
 \frametitle{Array creation functions cont.}
 \begin{itemize}
-\item \typ{ones(shape, dtype=None, ...)}
+\item \typ{np.ones(shape, dtype=None, ...)}
 \begin{lstlisting}
->>>ones([2,2])
+>>>np.ones([2,2])
 array([[ 1.,  1.],
 [ 1.,  1.]])
 \end{lstlisting}
-\item \typ{identity(n)}
+\item \typ{np.identity(n)}
-\item \typ{ones\_like(x)}
+\item \typ{np.ones\_like(x)}
 \begin{lstlisting}
->>>a = array([[1,2,3],[4,5,6]])
+>>>a = np.array([[1,2,3],[4,5,6]])
->>>ones_like(a)
+>>>np.ones_like(a)
 array([[1, 1, 1],
 [1, 1, 1]])
 \end{lstlisting}
-\item check out \typ{zeros, zeros\_like, empty}
+\item Also try \typ{zeros, zeros\_like, empty}
 \end{itemize}
 \end{frame}
 \begin{frame}[fragile]
 \frametitle{Slicing arrays}
 \begin{lstlisting}
->>> a = array([[1,2,3], [4,5,6],
+>>> a = np.array([[1,2,3], [4,5,6],
 [7,8,9]])
 >>> a[0,1:3]
 array([2, 3])
 >>> a[1:,1:]
 array([[5, 6],
 \begin{enumerate}
 \item Convert an RGB image to Grayscale. $ Y = 0.5R + 0.25G + 0.25B $
 \item Scale the image to 50\%
 \item Introduce some random noise
 \item Smooth the image using a mean filter
-\\\small{Take the mean of all the neighbouring elements}
+\\\small{Each element in the array is replaced by mean of all the neighbouring elements}
-\\\small{How fast can you do it?}
+\\\small{How fast does your code run?}
 \end{enumerate}
 \inctime{15}
 \end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \end{frame}
 \begin{frame}[fragile]
 \frametitle{Legends}
 \begin{lstlisting}
->>> x = linspace(0, 2*pi, 1000)
+>>> x = linspace(0, 2*np.pi, 1000)
 >>> plot(x, cos(5*x), 'r--',
 label='cosine')
 >>> plot(x, sin(5*x), 'g--',
 label='sine')
 >>> legend()
 \end{frame}
 \begin{frame}[fragile]
-\frametitle{Note: \typ{pylab} in Python scripts}
+\frametitle{\typ{pylab} in Python scripts}
 \begin{lstlisting}
 import pylab
 x = pylab.linspace(0, 20, 1000)
 pylab.plot(x, pylab.sin(x))
 # Can also use:
 from pylab import linspace, sin, plot
 \end{lstlisting}
-\inctime{5}
+\inctime{10}
 \end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \subsection{Types of Plots}
 \begin{frame}[fragile]
 \includegraphics[height=2.3in, interpolate=true]{data/plotmap}
 \begin{center}
 \tiny
 For details see \url{http://matplotlib.sourceforge.net/screenshots/plotmap.py}
 \end{center}
-\inctime{5}
 \end{frame}
 \begin{frame}
 \frametitle{More information}
 \begin{itemize}
 \item More information here: \url{http://matplotlib.sf.net}
 \item \url{http://matplotlib.sf.net/tutorial.html}
 \item \url{http://matplotlib.sf.net/screenshots.html}
 \end{itemize}
+\inctime{5}
 \end{frame}
 \begin{frame}
 \frametitle{Problem Set}
 \begin{enumerate}

changeset 66	523f788d2147
parent 46	63704b5650f1
child 76	b24c2560f626