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diff --git a/lecture-notes/advanced-python/slides/plotting.tex b/lecture-notes/advanced-python/slides/plotting.tex deleted file mode 100644 index fbc7aa2..0000000 --- a/lecture-notes/advanced-python/slides/plotting.tex +++ /dev/null @@ -1,450 +0,0 @@ -\section{Interactive Plotting} - -\begin{frame}[fragile] - \frametitle{First Plot} - \begin{itemize} - \item Start IPython with \texttt{-pylab} - \end{itemize} - \begin{lstlisting} - $ ipython -pylab - \end{lstlisting} % $ - \begin{lstlisting} - In[]: p = linspace(-pi,pi,100) - In[]: plot(p, cos(p)) - \end{lstlisting} -\end{frame} - - -\begin{frame}[fragile] - \frametitle{\texttt{linspace}} - \begin{itemize} - \item \texttt{p} has a hundred points in the range -pi to pi - \begin{lstlisting} - In[]: print p[0], p[-1], len(p) - \end{lstlisting} - \item Look at the doc-string of \texttt{linspace} for more details - \begin{lstlisting} - In[]: linspace? - \end{lstlisting} - \end{itemize} - \begin{itemize} - \item \texttt{plot} simply plots the two arguments with default - properties - \end{itemize} -\end{frame} - -\section{Embellishing Plots} - -\begin{frame}[fragile] - \frametitle{Plot color and thickness} - \begin{lstlisting} - In[]: clf() - In[]: plot(p, sin(p), 'r') - \end{lstlisting} - \begin{itemize} - \item Gives a sine curve in Red. - \end{itemize} - \begin{lstlisting} - In[]: plot(p, cos(p), linewidth=2) - \end{lstlisting} - \begin{itemize} - \item Sets line thickness to 2 - \end{itemize} - \begin{lstlisting} - In[]: clf() - In[]: plot(p, sin(p), '.') - \end{lstlisting} - \begin{itemize} - \item Produces a plot with only points - \end{itemize} - \begin{lstlisting} - In[]: plot? - \end{lstlisting} -\end{frame} - -\begin{frame}[fragile] - \frametitle{\texttt{title}} - \begin{lstlisting} - In[]: x = linspace(-2, 4, 50) - In[]: plot(x, -x*x + 4*x - 5, 'r', - linewidth=2) - In[]: title("Parabolic function -x^2+4x-5") - \end{lstlisting} - \begin{itemize} - \item We can set title using \LaTeX~ - \end{itemize} - \begin{lstlisting} - In[]: title("Parabolic function $-x^2+4x-5$") - \end{lstlisting} -\end{frame} - -\begin{frame}[fragile] - \frametitle{Axes labels} - \begin{lstlisting} - In[]: xlabel("x") - In[]: ylabel("f(x)") - \end{lstlisting} - \begin{itemize} - \item We could, if required use \LaTeX~ - \end{itemize} -\end{frame} - -\begin{frame}[fragile] - \frametitle{Annotate} - \begin{lstlisting} - In[]: annotate("local maxima", xy=(2, -1)) - \end{lstlisting} - \begin{itemize} - \item First argument is the annotation text - \item The argument to \texttt{xy} is a tuple that gives the location - of the text. - \end{itemize} -\end{frame} - -\begin{frame}[fragile] - \frametitle{Limits of Plot area} - \begin{lstlisting} - In[]: xlim() - In[]: ylim() - \end{lstlisting} - \begin{itemize} - \item With no arguments, \texttt{xlim} \& \texttt{ylim} get the - current limits - \item New limits are set, when arguments are passed to them - \end{itemize} - \begin{lstlisting} - In[]: xlim(-4, 5) - \end{lstlisting} - \begin{lstlisting} - In[]: ylim(-15, 2) - \end{lstlisting} -\end{frame} - -\begin{frame} -\frametitle{Plot} -\includegraphics[scale=0.45]{../advanced_python/images/plot.png}\\ -\end{frame} - - - -\section{Saving to Scripts} - -\begin{frame}[fragile] - \frametitle{Command history} - \begin{itemize} - \item To see the history of commands, we typed - \begin{lstlisting} - In[]: %hist - \end{lstlisting} - \item All commands, valid or invalid, appear in the history - \item \texttt{\%hist} is a magic command, available only in IPython - \end{itemize} - \begin{lstlisting} - In[]: %hist 5 - # last 5 commands - \end{lstlisting} - \begin{lstlisting} - In[]: %hist 5 10 - # commands between 5 and 10 - \end{lstlisting} -\end{frame} - -\begin{frame}[fragile] - \frametitle{Saving to a script} - \begin{itemize} - \item We wish to save commands for reproducing the parabola - \item Look at the history and identify the commands that will - reproduce the parabolic function along with all embellishment - \item \texttt{\%save} magic command to save the commands to a file - \end{itemize} - \begin{lstlisting} - In[]: %save plot_script.py 1 3-6 8 - \end{lstlisting} - \begin{itemize} - \item File name must have a \texttt{.py} extension - \end{itemize} -\end{frame} - -\begin{frame}[fragile] - \frametitle{Running the script} - \begin{lstlisting} - In[]: %run -i plot_script.py - \end{lstlisting} - \begin{itemize} - \item There were no errors in the plot, but we don't see it! - \item Running the script means, we are not in interactive mode - \item We need to explicitly ask for the image to be shown - \end{itemize} - \begin{lstlisting} - In[]: show() - \end{lstlisting} - \begin{itemize} - \item \texttt{-i} asks the interpreter to check for names, - unavailable in the script, in the interpreter - \item \texttt{sin}, \texttt{plot}, etc. are taken from the - interpreter - \end{itemize} -\end{frame} - -\section{Saving Plots} - -\begin{frame}[fragile] - \frametitle{\texttt{savefig}} - \begin{lstlisting} - In[]: x = linspace(-3*pi,3*pi,100) - In[]: plot(x,sin(x)) - In[]: savefig('sine.png') - \end{lstlisting} - \begin{itemize} - \item \texttt{savefig} takes one argument - \item The file-type is decided based on the extension - \item \texttt{savefig} can save as png, pdf, ps, eps, svg - \end{itemize} -\end{frame} - -\section{Multiple Plots} - -\begin{frame}[fragile] - \frametitle{Overlaid plots} - \begin{lstlisting} - In[]: x = linspace(0, 50, 10) - In[]: plot(x, sin(x)) - \end{lstlisting} - \begin{itemize} - \item The curve isn't as smooth as we expected - \item We chose too few points in the interval - \end{itemize} - \begin{lstlisting} - In[]: y = linspace(0, 50, 500) - In[]: plot(y, sin(y)) - \end{lstlisting} - \begin{itemize} - \item The plots are overlaid - \item It is the default behaviour of \texttt{pylab} - \end{itemize} -\end{frame} - -\begin{frame}[fragile] - \frametitle{Legend} - \begin{lstlisting} - In[]: legend(['sine-10 points', - 'sine-500 points']) - \end{lstlisting} - \begin{itemize} - \item Placed in the location, \texttt{pylab} thinks is `best' - \item \texttt{loc} parameter allows to change the location - \end{itemize} - \begin{lstlisting} - In[]: legend(['sine-10 points', - 'sine-500 points'], - loc='center') - \end{lstlisting} -\end{frame} - -\begin{frame} -\frametitle{Overlaid Plots} -\includegraphics[scale=0.45]{../advanced_python/images/overlaid.png}\\ -\end{frame} - - - -\begin{frame}[fragile] - \frametitle{Plotting in separate figures} - \begin{lstlisting} - In[]: clf() - In[]: x = linspace(0, 50, 500) - In[]: figure(1) - In[]: plot(x, sin(x), 'b') - In[]: figure(2) - In[]: plot(x, cos(x), 'g') - \end{lstlisting} - \begin{itemize} - \item \texttt{figure} command allows us to have plots separately - \item It is also used to switch context between the plots - \end{itemize} - \begin{lstlisting} - In[]: savefig('cosine.png') - In[]: figure(1) - In[]: title('sin(y)') - In[]: savefig('sine.png') - In[]: close() - In[]: close() - \end{lstlisting} - \begin{itemize} - \item \texttt{close('all')} closes all the figures - \end{itemize} -\end{frame} - -\begin{frame}[fragile] - \frametitle{Subplots} - \begin{lstlisting} - In[]: subplot(2, 1, 1) - \end{lstlisting} - \begin{itemize} - \item number of rows - \item number of columns - \item plot number, in serial order, to access or create - \end{itemize} - \begin{lstlisting} - In[]: subplot(2, 1, 2) - In[]: x = linspace(0, 50, 500) - In[]: plot(x, cos(x)) - - In[]: subplot(2, 1, 1) - In[]: y = linspace(0, 5, 100) - In[]: plot(y, y ** 2) - \end{lstlisting} -\end{frame} - -\begin{frame} -\frametitle{Subplots} -\includegraphics[scale=0.45]{../advanced_python/images/subplot.png}\\ -\end{frame} - - - -\section{Plotting Data} - -\begin{frame}[fragile] - \frametitle{Loading data} - \begin{itemize} - \item \texttt{primes.txt} contains a list of primes listed - column-wise - \item We read the data using \texttt{loadtxt} - \end{itemize} - \begin{lstlisting} - In[]: primes = loadtxt('primes.txt') - In[]: print primes - \end{lstlisting} - \begin{itemize} - \item \texttt{primes} is a sequence of floats - \end{itemize} -\end{frame} - -\begin{frame}[fragile] - \frametitle{Reading two column data} - \begin{itemize} - \item \texttt{pendulum.txt} has two columns of data - \item Length of pendulum in the first column - \item Corresponding time period in second column - \item \texttt{loadtxt} requires both columns to be of same length - \end{itemize} - \begin{lstlisting} - In[]: pend = loadtxt('pendulum.txt') - In[]: print pend - \end{lstlisting} - \begin{itemize} - \item \texttt{pend} is not a simple sequence like \texttt{primes} - \end{itemize} -\end{frame} - -\begin{frame}[fragile] - \frametitle{Unpacking with \texttt{loadtxt}} - \begin{lstlisting} - In[]: L, T = loadtxt('pendulum.txt', - unpack=True) - In[]: print L - In[]: print T - \end{lstlisting} - \begin{itemize} - \item We wish to plot L vs. $T^2$ - \item \texttt{square} function gives us the squares - \item (We could instead iterate over T and calculate) - \end{itemize} - \begin{lstlisting} - In[]: Tsq = square(T) - - In[]: plot(L, Tsq, '.') - \end{lstlisting} -\end{frame} - -\begin{frame}[fragile] - \frametitle{\texttt{errorbar}} - \begin{itemize} - \item Experimental data always has errors - \item \texttt{pendulum\_error.txt} contains errors in L and T - \item Read the values and make an error bar plot - \end{itemize} - \begin{lstlisting} - In[]: L, T, L_err, T_err = \ - loadtxt('pendulum_error.txt', - unpack=True) - In[]: Tsq = square(T) - - In[]: errorbar(L, Tsq , xerr=L_err, - yerr=T_err, fmt='b.') - \end{lstlisting} -\end{frame} - -\begin{frame} -\frametitle{Errorbar} -\includegraphics[scale=0.45]{../advanced_python/images/L-Tsq.png}\\ -\end{frame} - -\section{Other kinds of Plots} - -\begin{frame}[fragile] - \frametitle{Scatter Plot} - \begin{itemize} - \item The data is displayed as a collection of points - \item Value of one variable determines position along x-axis - \item Value of other variable determines position along y-axis - \item Let's plot the data of profits of a company - \end{itemize} - \begin{lstlisting} - In[]: year, profit = loadtxt( - 'company-a-data.txt', - dtype=type(int())) - - In[]: scatter(year, profit) - \end{lstlisting} - \begin{itemize} - \item \alert{\texttt{dtype=int}; default is float} - \end{itemize} -\end{frame} - -\begin{frame} -\frametitle{Scatter Plot} -\includegraphics[scale=0.45]{../advanced_python/images/scatter.png}\\ -\end{frame} - -\begin{frame}[fragile] - \frametitle{Pie Chart} - \begin{lstlisting} - In[]: pie(profit, labels=year) - \end{lstlisting} -\includegraphics[scale=0.35]{../advanced_python/images/pie.png}\\ -\end{frame} - -\begin{frame}[fragile] - \frametitle{Bar Chart} - \begin{lstlisting} - In[]: bar(year, profit) - \end{lstlisting} -\includegraphics[scale=0.35]{../advanced_python/images/bar.png}\\ -\end{frame} - -\begin{frame}[fragile] - \frametitle{Log-log plot} - \begin{itemize} - \item Plot a \texttt{log-log} chart of $y=5x^3$ for x from 1 to 20 - \end{itemize} - \begin{lstlisting} - In[]: x = linspace(1,20,100) - In[]: y = 5*x**3 - - In[]: loglog(x, y) - In[]: plot(x, y) - \end{lstlisting} - \begin{itemize} - \item Look at \url{http://matplotlib.sourceforge.net/contents.html} - for more! - \end{itemize} -\end{frame} - -\begin{frame} -\frametitle{Log-log plot Plot} -\includegraphics[scale=0.45]{../advanced_python/images/loglog.png}\\ -\end{frame} - - |