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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>5.43. Example - Custom Data Value Label Formatting</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-drawmessage.html" title="5.42. Example - DrawMessage" /><link rel="next" href="ex-imagemap-bars.html" title="5.44. Example - Image Map from Bar Chart" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">5.43. Example - Custom Data Value Label Formatting</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ex-drawmessage.html">Prev</a> </td><th width="60%" align="center">Chapter 5. PHPlot Examples</th><td width="20%" align="right"> <a accesskey="n" href="ex-imagemap-bars.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-dlexformat"></a>5.43. Example - Custom Data Value Label Formatting</h2></div></div></div><p>
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This example shows some advanced usage of label formatting. A user-defined
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function can be used to format labels, using the <code class="literal">custom</code>
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label type in <a class="xref" href="SetXLabelType.html" title="SetXLabelType"><span class="refentrytitle">SetXLabelType</span></a>, <a class="xref" href="SetYLabelType.html" title="SetYLabelType"><span class="refentrytitle">SetYLabelType</span></a>,
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<a class="xref" href="SetXDataLabelType.html" title="SetXDataLabelType"><span class="refentrytitle">SetXDataLabelType</span></a>, and <a class="xref" href="SetYDataLabelType.html" title="SetYDataLabelType"><span class="refentrytitle">SetYDataLabelType</span></a>.
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The user-defined function will have access to the row and column of the data
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point being plotted (for most data value labels), or the column (for axis data
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labels), and it can use these variables to control the formatting.
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</p><p>
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This example produces a linepoints plot with multiple data sets and with
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labels identifying the data values. The goal is to label only the greatest
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Y value for each X value. Before plotting, the data array is scanned to
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find the column index of the largest Y value for each row, and this
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information is stored in an array <code class="literal">$max_indexes</code>. That
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array is passed to the custom label formatting function as the pass-through
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argument. The label formatting function uses the array, along with the row
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and column of the point being labeled, to determine if a label should be
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produced or not.
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</p><p>
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Access to the data point row and column index was added in PHPlot-5.8.0.
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</p><div class="example"><a id="example-dlexformat"></a><p class="title"><strong>Example 5.43. Custom Data Value Label Formatting</strong></p><div class="example-contents"><div class="informalfigure"><div class="mediaobject"><img src="examples/dlexformat.png" alt="Custom Data Value Label Formatting Example" /></div></div><pre class="programlisting"><?php
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# PHPlot Example: Custom label formatting using row and column
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# This example produces a linepoints plot with only the maximum Y value
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# for each X value labeled. This is an example of a custom label
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# formatting with access to the data array position.
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# This requires PHPlot > 5.7.0
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require_once 'phplot.php';
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# Build a data array. The values are psuedo-random integers, but the first
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# and last rows have all Y=0. Return the completed data array.
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function make_data_array($n_rows, $n_y_per_row)
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{
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mt_srand(10); // For repeatable results
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$data[0] = array('', 0) + array_fill(2, $n_y_per_row, 0);
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for ($i = 1; $i < $n_rows - 1; $i++) {
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$row = array('', $i);
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for ($j = 0; $j < $n_y_per_row; $j++) $row[] = mt_rand(0, 999);
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$data[] = $row;
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}
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if ($n_rows > 1)
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$data[] = array('', $n_rows - 1) + array_fill(2, $n_y_per_row, 0);
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return $data;
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}
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# Find the index of the largest Y for each X in the data array.
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# Build an array $max_indexes such that $max_indexes[$row]=$column means
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# the $column-th Y value is the largest in row $row (where $row and $column
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# are zero-based). However, if max Y<=0 in the row, mark this with $column=-1
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# to prevent labeling. Returns the array $max_indexes.
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function find_max_indexes($data)
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{
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$max_indexes = array();
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foreach ($data as $row) {
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$max_index = 0;
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$max_y = $row[2]; // Skip label and X value
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// Process remaining values in the row:
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for ($j = 3; $j < count($row); $j++) {
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if ($row[$j] > $max_y) {
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$max_y = $row[$j];
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$max_index = $j - 2; // Offset by 2 for label and X value
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}
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}
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if ($max_y <= 0) $max_index = -1; // Will suppress the label
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$max_indexes[] = $max_index;
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}
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return $max_indexes;
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}
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# Custom label formatting function: Return an empty string, unless this is
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# the largest value in the row.
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function fmt_label($value, $maxes, $row, $column)
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{
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if ($maxes[$row] == $column) return $value;
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return "";
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}
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# Get the data array with 11 rows, 6 values per row:
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$data = make_data_array(11, 6);
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# Process the data array to find the largest Y per row:
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$max_indexes = find_max_indexes($data);
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# Now plot the data:
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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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$plot->SetPlotType('linepoints');
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$plot->SetDataType('data-data');
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$plot->SetDataValues($data);
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$plot->SetTitle('Linepoints plot with only max Y values labeled');
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$plot->SetYDataLabelPos('plotin');
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$plot->SetYDataLabelType('custom', 'fmt_label', $max_indexes);
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$plot->SetLineStyles('solid');
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$plot->SetYTickIncrement(100);
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$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-drawmessage.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-imagemap-bars.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">5.42. Example - DrawMessage </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 5.44. Example - Image Map from Bar Chart</td></tr></table></div></body></html>
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