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author Daniele Nicolodi <nicolodi@science.unitn.it>
date Wed, 23 Nov 2011 19:22:13 +0100
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11 <title>Split and join AOs (LTPDA Toolbox)</title>
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15 "Presents an overview of the features, system requirements, and starting the toolbox.">
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18 <body>
19 <a name="top_of_page" id="top_of_page"></a>
20
21 <p style="font-size:1px;">&nbsp;</p>
22
23 <table class="nav" summary="Navigation aid" border="0" width=
24 "100%" cellpadding="0" cellspacing="0">
25 <tr>
26 <td valign="baseline"><b>LTPDA Toolbox</b></td><td><a href="../helptoc.html">contents</a></td>
27
28 <td valign="baseline" align="right"><a href=
29 "ltpda_training_topic_2_7.html"><img src="b_prev.gif" border="0" align=
30 "bottom" alt="Select and find data from an AO"></a>&nbsp;&nbsp;&nbsp;<a href=
31 "ltpda_training_topic_2_9.html"><img src="b_next.gif" border="0" align=
32 "bottom" alt="IFO/Temperature Example - Pre-processing"></a></td>
33 </tr>
34 </table>
35
36 <h1 class="title"><a name="f3-12899" id="f3-12899"></a>Split and join AOs</h1>
37 <hr>
38
39 <p>
40 <p>
41 You can split the data inside an AO to produce one or more output AOs. The <tt>ao/split</tt> method
42 splits an AO by samples, times (if the AO contains time series data), frequencies (if the AO contains
43 frequency data), intervals, or a number of pieces. We can control this as usual by defining our parameters.
44 </p>
45 <h2>Split by times</h2>
46 <p>
47 Let us create a new time series AO for these examples.
48 </p>
49 <div class="fragment"><pre>
50 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>);
51 a = ao(pl);
52 </pre></div>
53 <p>
54 For splitting in time we need to define a time vector for the parameter list and pass it to <tt>ao/split</tt>
55 </p>
56 <div class="fragment"><pre>
57 pl_time = plist(<span class="string">'times'</span>, [2 3]);
58 a_time = split(a, pl_time);
59 iplot(a, a_time)
60 </pre></div>
61 <img src="images/ltpda_training_1/topic2/split_times.png" alt="split" border="1">
62
63 <h2>Split by frequencies</h2>
64 <p>
65 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>.
66 </p>
67 <div class="fragment"><pre>
68 axx = a.psd;
69 </pre></div>
70 <p>
71 Again we need a vector for the parameter list and pass it to <tt>ao/split</tt>
72 </p>
73
74 <div class="fragment"><pre>
75 pl_freq = plist(<span class="string">'frequencies'</span>, [10 100]);
76 axx_freq = split(axx, pl_freq);
77 iplot(axx, axx_freq)
78 </pre></div>
79 <img src="images/ltpda_training_1/topic2/split_freq.png" alt="split" border="1">
80
81 <h2>Split by intervals</h2>
82 <p>
83 We can also split the AO by passing a time interval to the <tt>ao/split</tt> method.
84 </p>
85
86 <div class="fragment"><pre>
87 pl_interv = plist(<span class="string">'start_time'</span>, 4, <span class="string">'end_time'</span>, 6);
88 a_interv= split(a, pl_interv);
89 iplot(a, a_interv)
90 </pre></div>
91 <img src="images/ltpda_training_1/topic2/split_interv.png" alt="split_interv" border="1">
92
93 <h2>Split by samples</h2>
94 <p>
95 This type of splitting method we can use on any type of data. Let us use the frequency type, <tt>axx</tt>.
96 </p>
97 <p>
98 Again we need a vector for the parameter list and pass it to <tt>ao/split</tt>,
99 only that this time we will split our AO in to two parts.
100 </p>
101
102 <div class="fragment"><pre>
103 pl_samp = plist(<span class="string">'samples'</span>, [50 100 101 300]);
104 [axx_samp1 axx_samp2]= split(axx, pl_samp)
105 iplot(axx, axx_samp1, axx_samp2)
106 </pre></div>
107 <img src="images/ltpda_training_1/topic2/split_samp.png" alt="split_samp" border="1">
108 <p>
109 Although in this example the two resulting AOs are contiguous, they need not to be.
110 </p>
111 <h2>Join AOs</h2>
112 <p>
113 We can join our two AOs back together using <tt>ao/join</tt>
114 </p>
115 <div class="fragment"><pre>
116 axx_join = join(axx_samp1, axx_samp2);
117 iplot(axx, axx_join)
118 </pre></div>
119 <img src="images/ltpda_training_1/topic2/split_join.png" alt="split_join" border="1">
120 <p>
121 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:
122 </p>
123 <img src="images/ltpda_training_1/topic2/split_join_hist.png" alt="Split/join history" width="800px" border="1">
124 <p>
125 Since the two AOs that are output from the 'split by samples' stage are independent, the history
126 tree reflects this, showing two independent branches leading to the <tt>join</tt> step.
127 </p>
128
129
130 </p>
131
132 <br>
133 <br>
134 <table class="nav" summary="Navigation aid" border="0" width=
135 "100%" cellpadding="0" cellspacing="0">
136 <tr valign="top">
137 <td align="left" width="20"><a href="ltpda_training_topic_2_7.html"><img src=
138 "b_prev.gif" border="0" align="bottom" alt=
139 "Select and find data from an AO"></a>&nbsp;</td>
140
141 <td align="left">Select and find data from an AO</td>
142
143 <td>&nbsp;</td>
144
145 <td align="right">IFO/Temperature Example - Pre-processing</td>
146
147 <td align="right" width="20"><a href=
148 "ltpda_training_topic_2_9.html"><img src="b_next.gif" border="0" align=
149 "bottom" alt="IFO/Temperature Example - Pre-processing"></a></td>
150 </tr>
151 </table><br>
152
153 <p class="copy">&copy;LTP Team</p>
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155 </html>