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<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" /><title>5.38. Example - Hourly Data Using X Tick Anchor</title><link rel="stylesheet" type="text/css" href="phplotdoc.css" /><meta name="generator" content="DocBook XSL Stylesheets V1.78.1" /><link rel="home" href="index.html" title="PHPlot Reference Manual" /><link rel="up" href="examples.html" title="Chapter 5. PHPlot Examples" /><link rel="prev" href="ex-ytickanchor.html" title="5.37. Example - Setting a Y Tick Anchor" /><link rel="next" href="ex-encodeimage.html" title="5.39. Example - Embedding Image with EncodeImage" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">5.38. Example - Hourly Data Using X Tick Anchor</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ex-ytickanchor.html">Prev</a> </td><th width="60%" align="center">Chapter 5. PHPlot Examples</th><td width="20%" align="right"> <a accesskey="n" href="ex-encodeimage.html">Next</a></td></tr></table><hr /></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ex-xtickanchor"></a>5.38. Example - Hourly Data Using X Tick Anchor</h2></div></div></div><p>
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This example uses an X tick anchor (see <a class="xref" href="SetXTickAnchor.html" title="SetXTickAnchor"><span class="refentrytitle">SetXTickAnchor</span></a>) to
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offset the X tick marks and grid lines. Hourly data is being plotted, for
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one week, and the goal is to have the tick marks and grid lines separate
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the days of the week, regardless of the time during the day of the initial
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data point.
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</p><p>
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In this example, both X axis data labels and X tick labels are turned on.
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The data labels display weekday names, and the tick labels display the dates.
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Having both labels on is usually something to avoid, because the labels will
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overlay.
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In this case, however, only 1 in 24 points has a data label (those points
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representing noon). Tick marks are also every 24 hours, but anchored at
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midnight. So the tick and data labels are separated.
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To avoid any overlap, the tick labels are drawn vertically (90 degrees)
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while the data labels are horizontal.
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</p><p>
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(Note that <a class="xref" href="SetXLabelAngle.html" title="SetXLabelAngle"><span class="refentrytitle">SetXLabelAngle</span></a> sets the angle for both tick
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and data labels, while <a class="xref" href="SetXDataLabelAngle.html" title="SetXDataLabelAngle"><span class="refentrytitle">SetXDataLabelAngle</span></a> sets the angle
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for data labels only. PHPlot does this to maintain compatibility.
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As a result, since the example here wants to turn the tick labels only
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(from the default 0 degrees), we also need to turn the data labels back to 0.
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The order of the calls does not matter, however.
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The same is true for label formatting with
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<a class="xref" href="SetXLabelType.html" title="SetXLabelType"><span class="refentrytitle">SetXLabelType</span></a> and <a class="xref" href="SetXDataLabelType.html" title="SetXDataLabelType"><span class="refentrytitle">SetXDataLabelType</span></a>.
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To get non-default tick label formatting and default data label formatting
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requires two calls as shown in the example.)
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</p><div class="example"><a id="example-xtickanchor"></a><p class="title"><strong>Example 5.38. Hourly Data Using X Tick Anchor</strong></p><div class="example-contents"><div class="informalfigure"><div class="mediaobject"><img src="examples/xtickanchor.png" alt="Hourly Data Using X Tick Anchor" /></div></div><pre class="programlisting"><?php
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# PHPlot Example: Using an X tick anchor to control grid lines
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# This example is based on a question on the PHPlot forum on 5/8/2011.
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# It requires PHPlot >= 5.4.0
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require_once 'phplot.php';
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# The first data point was recorded at this date/time: (always top of an hour)
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# Example: 5/1/2011 at 10:00am
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$year = 2011;
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$month = 5;
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$day = 1;
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$hour = 10;
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# Number of hourly data points, e.g. 168 for 1 week's worth:
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$n_points = 168;
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# ==================================================================
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# Timestamp for the first data point:
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$time0 = mktime($hour, 0, 0, $month, $day, $year); // H M S m d y
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mt_srand(1); // For repeatable, identical results
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# Build the PHPlot data array from the base data, and base timestamp.
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$data = array();
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$ts = $time0;
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$tick_anchor = NULL;
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$d = 5; // Data value
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for ($i = 0; $i < $n_points; $i++) {
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# Decode this point's timestamp as hour 0-23:
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$hour = date('G', $ts);
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# Label noon data points with the weekday name, all others unlabelled.
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$label = ($hour == 12) ? strftime('%A', $ts) : '';
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# Remember the first midnight datapoint seen for use as X tick anchor:
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if (!isset($tick_anchor) && $hour == 0)
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$tick_anchor = $ts;
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# Make a random data point, and add a row to the data array:
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$d += mt_rand(-200, 250) / 100;
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$data[] = array($label, $ts, $d);
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# Step to next hour:
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$ts += 3600;
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}
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$plot = new PHPlot(800, 600);
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$plot->SetImageBorderType('plain'); // For presentation in the manual
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$plot->SetTitle('Hourly Data Example Plot');
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$plot->SetDataType('data-data');
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$plot->SetDataValues($data);
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$plot->SetPlotType('lines');
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# Make the X tick marks (and therefore X grid lines) 24 hours apart:
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$plot->SetXTickIncrement(60 * 60 * 24);
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$plot->SetDrawXGrid(True);
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# Anchor the X tick marks at midnight. This makes the X grid lines act as
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# separators between days of the week, regardless of the starting hour.
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# (Except this messes up around daylight saving time changes.)
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$plot->SetXTickAnchor($tick_anchor);
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# We want both X axis data labels and X tick labels displayed. They will
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# be positioned in a way that prevents them from overwriting.
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$plot->SetXDataLabelPos('plotdown');
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$plot->SetXTickLabelPos('plotdown');
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# Increase the left and right margins to leave room for weekday labels.
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$plot->SetMarginsPixels(50, 50);
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# Tick labels will be formatted as date/times, showing the date:
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$plot->SetXLabelType('time', '%Y-%m-%d');
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# ... but then we must reset the data label formatting to no formatting.
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$plot->SetXDataLabelType('');
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# Show tick labels (with dates) at 90 degrees, to fit between the data labels.
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$plot->SetXLabelAngle(90);
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# ... but then we must reset the data labels to 0 degrees.
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$plot->SetXDataLabelAngle(0);
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# Force the Y range to 0:100.
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$plot->SetPlotAreaWorld(NULL, 0, NULL, 100);
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# Now draw the graph:
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$plot->DrawGraph();
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</pre></div></div><br class="example-break" /></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ex-ytickanchor.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="examples.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ex-encodeimage.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">5.37. Example - Setting a Y Tick Anchor </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 5.39. Example - Embedding Image with EncodeImage</td></tr></table></div></body></html>
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