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author | Daniele Nicolodi <nicolodi@science.unitn.it> |
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date | Wed, 23 Nov 2011 19:22:13 +0100 |
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/1999/REC-html401-19991224/loose.dtd"> <html lang="en"> <head> <meta name="generator" content= "HTML Tidy for Mac OS X (vers 1st December 2004), see www.w3.org"> <meta http-equiv="Content-Type" content= "text/html; charset=us-ascii"> <title>Split and join AOs (LTPDA Toolbox)</title> <link rel="stylesheet" href="docstyle.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.52.2"> <meta name="description" content= "Presents an overview of the features, system requirements, and starting the toolbox."> </head> <body> <a name="top_of_page" id="top_of_page"></a> <p style="font-size:1px;"> </p> <table class="nav" summary="Navigation aid" border="0" width= "100%" cellpadding="0" cellspacing="0"> <tr> <td valign="baseline"><b>LTPDA Toolbox</b></td><td><a href="../helptoc.html">contents</a></td> <td valign="baseline" align="right"><a href= "ltpda_training_topic_2_7.html"><img src="b_prev.gif" border="0" align= "bottom" alt="Select and find data from an AO"></a> <a href= "ltpda_training_topic_2_9.html"><img src="b_next.gif" border="0" align= "bottom" alt="IFO/Temperature Example - Pre-processing"></a></td> </tr> </table> <h1 class="title"><a name="f3-12899" id="f3-12899"></a>Split and join AOs</h1> <hr> <p> <p> You can split the data inside an AO to produce one or more output AOs. The <tt>ao/split</tt> method splits an AO by samples, times (if the AO contains time series data), frequencies (if the AO contains frequency data), intervals, or a number of pieces. We can control this as usual by defining our parameters. </p> <h2>Split by times</h2> <p> Let us create a new time series AO for these examples. </p> <div class="fragment"><pre> pl = plist(<span class="string">'name'</span>, <span class="string">'None'</span>, <span class="string">'nsecs'</span>, 10, <span class="string">'fs'</span>, 1000, <span class="string">'tsfcn'</span>, <span class="string">'sin(2*pi*7.433*t) + randn(size(t))'</span>,<span class="string">'yunits'</span>,<span class="string">'V'</span>); a = ao(pl); </pre></div> <p> For splitting in time we need to define a time vector for the parameter list and pass it to <tt>ao/split</tt> </p> <div class="fragment"><pre> pl_time = plist(<span class="string">'times'</span>, [2 3]); a_time = split(a, pl_time); iplot(a, a_time) </pre></div> <img src="images/ltpda_training_1/topic2/split_times.png" alt="split" border="1"> <h2>Split by frequencies</h2> <p> For this we need a frequency data AO. One easy way to get this is by computing the power spectrum using <tt>ao/psd</tt>. </p> <div class="fragment"><pre> axx = a.psd; </pre></div> <p> Again we need a vector for the parameter list and pass it to <tt>ao/split</tt> </p> <div class="fragment"><pre> pl_freq = plist(<span class="string">'frequencies'</span>, [10 100]); axx_freq = split(axx, pl_freq); iplot(axx, axx_freq) </pre></div> <img src="images/ltpda_training_1/topic2/split_freq.png" alt="split" border="1"> <h2>Split by intervals</h2> <p> We can also split the AO by passing a time interval to the <tt>ao/split</tt> method. </p> <div class="fragment"><pre> pl_interv = plist(<span class="string">'start_time'</span>, 4, <span class="string">'end_time'</span>, 6); a_interv= split(a, pl_interv); iplot(a, a_interv) </pre></div> <img src="images/ltpda_training_1/topic2/split_interv.png" alt="split_interv" border="1"> <h2>Split by samples</h2> <p> This type of splitting method we can use on any type of data. Let us use the frequency type, <tt>axx</tt>. </p> <p> Again we need a vector for the parameter list and pass it to <tt>ao/split</tt>, only that this time we will split our AO in to two parts. </p> <div class="fragment"><pre> pl_samp = plist(<span class="string">'samples'</span>, [50 100 101 300]); [axx_samp1 axx_samp2]= split(axx, pl_samp) iplot(axx, axx_samp1, axx_samp2) </pre></div> <img src="images/ltpda_training_1/topic2/split_samp.png" alt="split_samp" border="1"> <p> Although in this example the two resulting AOs are contiguous, they need not to be. </p> <h2>Join AOs</h2> <p> We can join our two AOs back together using <tt>ao/join</tt> </p> <div class="fragment"><pre> axx_join = join(axx_samp1, axx_samp2); iplot(axx, axx_join) </pre></div> <img src="images/ltpda_training_1/topic2/split_join.png" alt="split_join" border="1"> <p> If we look at the history for <tt>axx_join</tt> (for instance, by entering <tt>dotview(axx_join.hist)</tt>), we will see the following: </p> <img src="images/ltpda_training_1/topic2/split_join_hist.png" alt="Split/join history" width="800px" border="1"> <p> Since the two AOs that are output from the 'split by samples' stage are independent, the history tree reflects this, showing two independent branches leading to the <tt>join</tt> step. </p> </p> <br> <br> <table class="nav" summary="Navigation aid" border="0" width= "100%" cellpadding="0" cellspacing="0"> <tr valign="top"> <td align="left" width="20"><a href="ltpda_training_topic_2_7.html"><img src= "b_prev.gif" border="0" align="bottom" alt= "Select and find data from an AO"></a> </td> <td align="left">Select and find data from an AO</td> <td> </td> <td align="right">IFO/Temperature Example - Pre-processing</td> <td align="right" width="20"><a href= "ltpda_training_topic_2_9.html"><img src="b_next.gif" border="0" align= "bottom" alt="IFO/Temperature Example - Pre-processing"></a></td> </tr> </table><br> <p class="copy">©LTP Team</p> </body> </html>