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								  <h1>DataView</h1>
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								  <h2 id="Contents">Contents</h2>
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								  <ul>
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								    <li><a href="#Overview">Overview</a></li>
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								    <li><a href="#Example">Example</a></li>
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								    <li><a href="#Construction">Construction</a></li>
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								    <li><a href="#Methods">Methods</a></li>
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								    <li><a href="#Properties">Properties</a></li>
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								    <li><a href="#Getting_Data">Getting Data</a></li>
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								    <li><a href="#Subscriptions">Subscriptions</a></li>
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								  </ul>
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								  <h2 id="Overview">Overview</h2>
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								  <p>
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								    A DataView offers a filtered and/or formatted view on a
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								    <a href="dataset.html">DataSet</a>.
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								    One can subscribe to changes in a DataView, and easily get filtered or
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								    formatted data without having to specify filters and field types all
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								    the time.
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								  </p>
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								  <h2 id="Example">Example</h2>
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								  <p>
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								    The following example shows how to use a DataView.
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								  </p>
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								<pre class="prettyprint lang-js">
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								// create a DataSet
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								var data = new vis.DataSet();
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								data.add([
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								  {id: 1, text: 'item 1', date: new Date(2013, 6, 20), group: 1, first: true},
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								  {id: 2, text: 'item 2', date: '2013-06-23', group: 2},
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								  {id: 3, text: 'item 3', date: '2013-06-25', group: 2},
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								  {id: 4, text: 'item 4'}
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								]);
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								// create a DataView
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								// the view will only contain items having a property group with value 1,
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								// and will only output fields id, text, and date.
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								var view = new vis.DataView(data, {
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								  filter: function (item) {
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								    return (item.group == 1);
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								  },
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								  fields: ['id', 'text', 'date']
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								});
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								// subscribe to any change in the DataView
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								view.on('*', function (event, properties, senderId) {
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								  console.log('event', event, properties);
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								});
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								// update an item in the data set
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								data.update({id: 2, group: 1});
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								// get all ids in the view
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								var ids = view.getIds();
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								console.log('ids', ids); // will output [1, 2]
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								// get all items in the view
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								var items = view.get();
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								</pre>
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								  <h2 id="Construction">Construction</h2>
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								  <p>
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								    A DataView can be constructed as:
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								  </p>
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								<pre class="prettyprint lang-js">
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								var data = new vis.DataView(dataset, options)
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								</pre>
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								  <p>
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								    where:
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								  </p>
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								  <ul>
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								    <li>
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								      <code>dataset</code> is a DataSet or DataView.
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								    </li>
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								    <li>
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								      <code>options</code> is an object which can
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								      contain the following properties. Note that these properties
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								      are exactly the same as the properties available in methods
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								      <code>DataSet.get</code> and <code>DataView.get</code>.
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								      <table class="options">
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								        <tr>
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								          <th>Name</th>
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								          <th>Type</th>
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								          <th>Default</th>
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								          <th>Description</th>
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								        </tr>
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								        <tr>
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								          <td>convert</td>
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								          <td>Object.<String, String></td>
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								          <td>none</td>
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								          <td>
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								            An object containing field names as key, and data types as value.
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								            By default, the type of the properties of an item are left
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								            unchanged. When a field type is specified, this field in the
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								            items will be converted to the specified type. This can be used
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								            for example to convert ISO strings containing a date to a
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								            JavaScript Date object, or convert strings to numbers or vice
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								            versa. The available data types are listed in section
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								            <a href="dataset.html#Data_Types">Data Types</a>.
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								          </td>
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								        </tr>
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								        <tr>
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								          <td>fields</td>
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								          <td>String[ ] | Object.<String, String></td>
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								          <td>none</td>
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								          <td>
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								            An array with field names, or an object with current field name and
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								            new field name that the field is returned as.
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								            By default, all properties of the items are emitted.
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								            When <code>fields</code> is defined, only the properties
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								            whose name is specified in <code>fields</code> will be included
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								            in the returned items.
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								          </td>
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								        </tr>
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								        <tr>
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								          <td>filter</td>
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								          <td>function</td>
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								          <td>none</td>
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								          <td>Items can be filtered on specific properties by providing a filter
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								            function. A filter function is executed for each of the items in the
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								            DataSet, and is called with the item as parameter. The function must
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								            return a boolean. All items for which the filter function returns
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								            true will be emitted.
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								            See also section <a href="dataset.html#Data_Filtering">Data Filtering</a>.</td>
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								        </tr>
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								      </table>
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								    </li>
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								  </ul>
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								  <h2 id="Methods">Methods</h2>
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								  <p>DataView contains the following methods.</p>
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								  <table class="methods">
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								    <tr>
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								      <th>Method</th>
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								      <th>Return Type</th>
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								      <th>Description</th>
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								    </tr>
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								    <tr>
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								      <td>
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								        get([options] [, data])<br>
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								        get(id [,options] [, data])<br>
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								        get(ids [, options] [, data])
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								      </td>
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								      <td>Object | Array</td>
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								      <td>
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								        Get a single item, multiple items, or all items from the DataView.
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								        Usage examples can be found in section <a href="#Getting_Data">Getting Data</a>, and the available <code>options</code> are described in section <a href="#Data_Selection">Data Selection</a>.
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								      </td>
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								    </tr>
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								    <tr>
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								      <td>
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								        getDataSet()
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								      </td>
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								      <td>DataSet</td>
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								      <td>
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								        Get the DataSet to which the DataView is connected.
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								      </td>
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								    </tr>
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								    <tr>
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								      <td>
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								        getIds([options])
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								      </td>
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								      <td>Number[]</td>
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								      <td>
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								        Get ids of all items or of a filtered set of items.
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								        Available <code>options</code> are described in section <a href="dataset.html#Data_Selection">Data Selection</a>, except that options <code>fields</code> and <code>type</code> are not applicable in case of <code>getIds</code>.
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								      </td>
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								    </tr>
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								    <tr>
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								      <td>off(event, callback)</td>
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								      <td>none</td>
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								      <td>
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								        Unsubscribe from an event, remove an event listener. See section <a href="#Subscriptions">Subscriptions</a>.
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								      </td>
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								    </tr>
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								    <tr>
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								      <td>on(event, callback)</td>
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								      <td>none</td>
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								      <td>
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								        Subscribe to an event, add an event listener. See section <a href="#Subscriptions">Subscriptions</a>.
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								      </td>
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								    </tr>
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								    <tr>
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								      <td>refresh()</td>
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								      <td>none</td>
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								      <td>
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								        Refresh the filter results of a DataView. Useful when the filter function contains dynamic properties, like:
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						|
								      <pre class="prettyprint lang-js">var data = new vis.DataSet(...);
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								var view = new vis.DataView(data, {
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								  filter: function (item) {
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								    return item.value > threshold;
							 | 
						|
								  }
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						|
								});</pre>
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						|
								        In this example, <code>threshold</code> is an external parameter. When the value of <code>threshold</code> changes, the DataView must be notified that the filter results may have changed by calling <code>DataView.refresh()</code>.
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								      </td>
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								    </tr>
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								    <tr>
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								      <td>
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								        setDataSet(data)
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						|
								      </td>
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								      <td>none</td>
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						|
								      <td>
							 | 
						|
								        Replace the DataSet of the DataView. Parameter <code>data</code> can be a DataSet or a DataView.
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						|
								      </td>
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						|
								    </tr>
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						|
								
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								  </table>
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								  <h2 id="Properties">Properties</h2>
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						|
								
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								  <p>DataView contains the following properties.</p>
							 | 
						|
								
							 | 
						|
								  <table>
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						|
								    <colgroup>
							 | 
						|
								      <col width="200">
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						|
								    </colgroup>
							 | 
						|
								
							 | 
						|
								    <tr>
							 | 
						|
								      <th>Property</th>
							 | 
						|
								      <th>Type</th>
							 | 
						|
								      <th>Description</th>
							 | 
						|
								    </tr>
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						|
								
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						|
								    <tr>
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						|
								      <td>length</td>
							 | 
						|
								      <td>Number</td>
							 | 
						|
								      <td>The number of items in the DataView.</td>
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						|
								    </tr>
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						|
								  </table>
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						|
								
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								  <h2 id="Getting_Data">Getting Data</h2>
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						|
								
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						|
								  <p>
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						|
								    Data of the DataView can be retrieved using the method <code>get</code>.
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						|
								  </p>
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						|
								
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								<pre class="prettyprint lang-js">
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						|
								var items = view.get();
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								</pre>
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						|
								
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								  <p>
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								    Data of a DataView can be filtered and formatted again, in exactly the
							 | 
						|
								    same way as in a DataSet. See sections
							 | 
						|
								    <a href="dataset.html#Data_Manipulation">Data Manipulation</a> and
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						|
								    <a href="dataset.html#Data_Selection">Data Selection</a> for more
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						|
								    information.
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								  </p>
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								<pre class="prettyprint lang-js">
							 | 
						|
								var items = view.get({
							 | 
						|
								  fields: ['id', 'score'],
							 | 
						|
								  filter: function (item) {
							 | 
						|
								    return (item.score > 50);
							 | 
						|
								  }
							 | 
						|
								});
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						|
								</pre>
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								  <h2 id="Subscriptions">Subscriptions</h2>
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						|
								  <p>
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						|
								    One can subscribe on changes in the DataView. Subscription works exactly
							 | 
						|
								    the same as for DataSets. See the documentation on
							 | 
						|
								    <a href="dataset.html#Subscriptions">subscriptions in a DataSet</a>
							 | 
						|
								    for more information.
							 | 
						|
								  </p>
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						|
								
							 | 
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								<pre class="prettyprint lang-js">
							 | 
						|
								// create a DataSet and a view on the data set
							 | 
						|
								var data = new vis.DataSet();
							 | 
						|
								var view = new vis.DataView({
							 | 
						|
								  filter: function (item) {
							 | 
						|
								    return (item.group == 2);
							 | 
						|
								  }
							 | 
						|
								});
							 | 
						|
								
							 | 
						|
								// subscribe to any change in the DataView
							 | 
						|
								view.on('*', function (event, properties, senderId) {
							 | 
						|
								  console.log('event:', event, 'properties:', properties, 'senderId:', senderId);
							 | 
						|
								});
							 | 
						|
								
							 | 
						|
								// add, update, and remove data in the DataSet...
							 | 
						|
								</pre>
							 | 
						|
								
							 | 
						|
								</div>
							 | 
						|
								
							 | 
						|
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