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author Daniele Nicolodi <nicolodi@science.unitn.it>
date Wed, 23 Nov 2011 19:22:13 +0100
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+  <title>Select and find data from an AO (LTPDA Toolbox)</title>
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+  <a name="top_of_page" id="top_of_page"></a>
+
+  <p style="font-size:1px;">&nbsp;</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_6.html"><img src="b_prev.gif" border="0" align=
+      "bottom" alt="Whitening noise"></a>&nbsp;&nbsp;&nbsp;<a href=
+      "ltpda_training_topic_2_8.html"><img src="b_next.gif" border="0" align=
+      "bottom" alt="Split and join AOs"></a></td>
+    </tr>
+  </table>
+
+  <h1 class="title"><a name="f3-12899" id="f3-12899"></a>Select and find data from an AO</h1>
+  <hr>
+  
+  <p>
+	
+<p>
+  LTPDA contains a set of methods that can be used for the selection of data from an AO. In this section
+  we will in particular look at <tt>ao/find</tt> and <tt>ao/select</tt>.
+</p>
+<p>
+  We will start by generating a sine wave:
+</p>
+<div class="fragment"><pre>
+    pl = plist(<span class="string">'waveform'</span>, <span class="string">'sine wave'</span>,  <span class="string">'f'</span>, 1, <span class="string">'fs'</span>, 100, <span class="string">'nsecs'</span>, 10, <span class="string">'yunits'</span>, <span class="string">'V'</span>);
+    a  = ao(pl)
+</pre></div>
+
+<br>
+<h2>Example 1 - using <tt>find</tt></h2>
+<p>
+  Now let us use the <tt>find</tt> method to extract parts of the data we are interested in.
+</p>
+<p>
+  The <tt>find</tt> method can take a parameter 'query' for defining which data points you want to find. The
+  query string can be any valid MATLAB logical expression, and in particular can be expressed in terms of the
+  x and y data of the input AO. 
+</p>
+<p>
+  In this example, we want to find all x values between 3 and 6. The following code does just that:
+</p>
+<div class="fragment"><pre>
+    a_find = find(a, plist(<span class="string">'query'</span>, <span class="string">'x&gt;3 &amp; x&lt;6'</span>));
+    iplot(a, a_find)
+</pre></div>
+<img src="images/ltpda_training_1/topic2/find.png" alt="find" border="1">
+<br>
+<h2>Example 2 - using <tt>select</tt></h2>
+<p>
+  The <tt>select</tt> method lets us select a set of data samples from our AO.
+  For this we need a <tt>plist</tt> containing an array of samples we want to select.
+  We take our sine wave again which is stored in the variable <tt>a</tt> to see how it works. 
+</p>
+<div class="fragment"><pre>
+    a_select = select(a, plist(<span class="string">'samples'</span>, 200:800));
+    iplot(a, a_select)
+</pre></div>
+<img src="images/ltpda_training_1/topic2/select.png" alt="select" border="1">
+
+  </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_6.html"><img src=
+      "b_prev.gif" border="0" align="bottom" alt=
+      "Whitening noise"></a>&nbsp;</td>
+
+      <td align="left">Whitening noise</td>
+
+      <td>&nbsp;</td>
+
+      <td align="right">Split and join AOs</td>
+
+      <td align="right" width="20"><a href=
+      "ltpda_training_topic_2_8.html"><img src="b_next.gif" border="0" align=
+      "bottom" alt="Split and join AOs"></a></td>
+    </tr>
+  </table><br>
+
+  <p class="copy">&copy;LTP Team</p>
+</body>
+</html>