phplot 多色显示数据

<?php# PHPlot Example: Bar chart with bar color depending on valuerequire_once 'phplot.php';# Callback for picking a data color.# PHPlot will call this every time it needs a data color.# This returns a color index which depends on the data value.# Color 0 is for values >= 80%, 1 is for >= 60%, 2 is for < 60%.# The data_array must have 'text-data' type.function pickcolor($img, $data_array, $row, $col){  $d = $data_array[$row][$col+1]; // col+1 skips over the row's label  if ($d >= 80) return 0;  if ($d >= 60) return 1;  return 2;}# The data array has our monthly performance as a percentage.$data = array(    array('Jan',  95), array('Feb',  75), array('Mar',  83),    array('Apr',  66), array('May',  90), array('Jun',  80),    array('Jul',  70), array('Aug',  50), array('Sep',  60),    array('Oct',  70), array('Nov',  80), array('Dec',  45),);$plot = new PHPlot(800, 600);$plot->SetImageBorderType('plain'); // Improves presentation in the manual$plot->SetPlotType('bars');$plot->SetDataValues($data);$plot->SetDataType('text-data');$plot->SetTitle('Monthly Performance Rating');# Turn off X Tick labels which have no meaning here.$plot->SetXTickPos('none');# Force the Y axis to be exactly 0:100$plot->SetPlotAreaWorld(NULL, 0, NULL, 100);# Establish the function 'pickcolor' as a data color selection callback.# Set the $data array as the pass-through argument, so the function has# access to the data values without relying on global variables.$plot->SetCallback('data_color', 'pickcolor', $data);# The three colors are meaningful to the data color callback.$plot->SetDataColors(array('green', 'yellow', 'red'));# The legend will explain the use of the 3 colors.$plot->SetLegend(array('Exceeded expectations', 'Met expectations',  'Failed to meet expectations'));$plot->DrawGraph();