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<td >Qt 5.9</td><td ><a href="qtcharts-index.html">Qt Charts</a></td><td ><a href="qtcharts-examples.html">Qt Charts Examples</a></td><td >Logarithmic Axis Example</td></tr></table><table class="buildversion"><tr>
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<h3><a name="toc">Contents</a></h3>
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<li class="level1"><a href="#running-the-example">Running the Example</a></li>
<li class="level1"><a href="#using-logarithmic-value-axes">Using Logarithmic Value Axes</a></li>
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<h1 class="title">Logarithmic Axis Example</h1>
<span class="subtitle"></span>
<!-- $$$logvalueaxis-description -->
<div class="descr"> <a name="details"></a>
<p class="centerAlign"><img src="images/examples_logvalueaxis.png" alt="" /></p><a name="running-the-example"></a>
<h2 id="running-the-example">Running the Example</h2>
<p>To run the example from Qt Creator, open the <b>Welcome</b> mode and select the example from <b>Examples</b>. For more information, visit Building and Running an Example.</p>
<a name="using-logarithmic-value-axes"></a>
<h2 id="using-logarithmic-value-axes">Using Logarithmic Value Axes</h2>
<p>Create a <a href="qlineseries.html">QLineSeries</a> instance and add some data to it.</p>
<pre class="cpp">
<span class="type"><a href="qlineseries.html">QLineSeries</a></span> <span class="operator">*</span>series <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qlineseries.html">QLineSeries</a></span>();
<span class="operator">*</span>series <span class="operator"><</span><span class="operator"><</span> <span class="type">QPointF</span>(<span class="number">1.0</span><span class="operator">,</span> <span class="number">1.0</span>) <span class="operator"><</span><span class="operator"><</span> <span class="type">QPointF</span>(<span class="number">2.0</span><span class="operator">,</span> <span class="number">73.0</span>) <span class="operator"><</span><span class="operator"><</span> <span class="type">QPointF</span>(<span class="number">3.0</span><span class="operator">,</span> <span class="number">268.0</span>) <span class="operator"><</span><span class="operator"><</span> <span class="type">QPointF</span>(<span class="number">4.0</span><span class="operator">,</span> <span class="number">17.0</span>)
<span class="operator"><</span><span class="operator"><</span> <span class="type">QPointF</span>(<span class="number">5.0</span><span class="operator">,</span> <span class="number">4325.0</span>) <span class="operator"><</span><span class="operator"><</span> <span class="type">QPointF</span>(<span class="number">6.0</span><span class="operator">,</span> <span class="number">723.0</span>);
</pre>
<p>To present the data on the chart we need a <a href="qchart.html">QChart</a> instance. Add the series to it, hide the legend and set the title of the chart.</p>
<pre class="cpp">
<span class="type"><a href="qchart.html">QChart</a></span> <span class="operator">*</span>chart <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qchart.html">QChart</a></span>();
chart<span class="operator">-</span><span class="operator">></span>addSeries(series);
chart<span class="operator">-</span><span class="operator">></span>legend()<span class="operator">-</span><span class="operator">></span>hide();
chart<span class="operator">-</span><span class="operator">></span>setTitle(<span class="string">"Logarithmic axis example"</span>);
</pre>
<p>Create the axes. Add them to the chart and attach to the series.</p>
<pre class="cpp">
<span class="type"><a href="qvalueaxis.html">QValueAxis</a></span> <span class="operator">*</span>axisX <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qvalueaxis.html">QValueAxis</a></span>();
axisX<span class="operator">-</span><span class="operator">></span>setTitleText(<span class="string">"Data point"</span>);
axisX<span class="operator">-</span><span class="operator">></span>setLabelFormat(<span class="string">"%i"</span>);
axisX<span class="operator">-</span><span class="operator">></span>setTickCount(series<span class="operator">-</span><span class="operator">></span>count());
chart<span class="operator">-</span><span class="operator">></span>addAxis(axisX<span class="operator">,</span> <span class="type">Qt</span><span class="operator">::</span>AlignBottom);
series<span class="operator">-</span><span class="operator">></span>attachAxis(axisX);
<span class="type"><a href="qlogvalueaxis.html">QLogValueAxis</a></span> <span class="operator">*</span>axisY <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qlogvalueaxis.html">QLogValueAxis</a></span>();
axisY<span class="operator">-</span><span class="operator">></span>setTitleText(<span class="string">"Values"</span>);
axisY<span class="operator">-</span><span class="operator">></span>setLabelFormat(<span class="string">"%g"</span>);
axisY<span class="operator">-</span><span class="operator">></span>setBase(<span class="number">8.0</span>);
axisY<span class="operator">-</span><span class="operator">></span>setMinorTickCount(<span class="operator">-</span><span class="number">1</span>);
chart<span class="operator">-</span><span class="operator">></span>addAxis(axisY<span class="operator">,</span> <span class="type">Qt</span><span class="operator">::</span>AlignLeft);
series<span class="operator">-</span><span class="operator">></span>attachAxis(axisY);
</pre>
<p>Then create a <a href="qchartview.html">QChartView</a> object with <a href="qchart.html">QChart</a> as a parameter. Enable antialiasing to have the rendered line look nicer.</p>
<pre class="cpp">
<span class="type"><a href="qchartview.html">QChartView</a></span> <span class="operator">*</span>chartView <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qchartview.html">QChartView</a></span>(chart);
chartView<span class="operator">-</span><span class="operator">></span>setRenderHint(<span class="type">QPainter</span><span class="operator">::</span>Antialiasing);
</pre>
<p>The chart is ready to be shown.</p>
<pre class="cpp">
<span class="type">QMainWindow</span> window;
window<span class="operator">.</span>setCentralWidget(chartView);
window<span class="operator">.</span>resize(<span class="number">800</span><span class="operator">,</span> <span class="number">600</span>);
window<span class="operator">.</span>show();
</pre>
<p>Files:</p>
<ul>
<li><a href="qtcharts-logvalueaxis-main-cpp.html">logvalueaxis/main.cpp</a></li>
<li><a href="qtcharts-logvalueaxis-logvalueaxis-pro.html">logvalueaxis/logvalueaxis.pro</a></li>
</ul>
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19952c5e751bf7e3108c3c59625b0f35
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