# Make some pseudo-random data.
mt_srand(1);
$data = array();
$value = 10;
for ($i = 0; $i < 500; $i++) {
$data[] = array('', $i, $value);
$value = max(0, $value + mt_rand(-9, 10));
}
# Make a color gradient array of blue:
$colors = array();
for ($b = 32; $b <= 255; $b += 2) {
$colors[] = array(0, 0, $b);
}
for ($b = 255; $b >= 32; $b -= 2) {
$colors[] = array(0, 0, $b);
}
# Use a truecolor plot image in order to get more colors.
$plot = new PHPlot_truecolor(800, 600);
$plot->SetImageBorderType('plain');
// Improves presentation in the manual
$plot->SetPlotType('thinbarline');
$plot->SetDataType('data-data');
$plot->SetDataValues($data);
$plot->SetLineWidths(2);
$plot->SetDataColors($colors);
$plot->SetXTickPos('none');
$plot->SetPlotAreaWorld(0, 0, 500, NULL);
$plot->SetTitle('Meaningless Data with Color Gradient');
# Establish the function 'getcolor' as a data color selection callback.
$plot->SetCallback('data_color', 'getcolor');
$plot->DrawGraph();