负数时更改线条颜色

Question

我想用Pchart制作温度线图 我需要的是正温度是红色和负蓝色 关于如何实现这种效果的任何想法？

Answer 1

在pChart示例中，请参阅页面[示例＆gt;面积图＆gt; drawAreaChart.threshold。 如果它们位于您配置的阈值内，则会对区域的某些部分（区域图）进行着色。

该示例中的代码段：

/* Draw the area chart */
$Threshold = "";
$Threshold[] = array("Min"=>0,"Max"=>5,"R"=>187,"G"=>220,"B"=>0,"Alpha"=>100);
$Threshold[] = array("Min"=>5,"Max"=>10,"R"=>240,"G"=>132,"B"=>20,"Alpha"=>100);
$Threshold[] = array("Min"=>10,"Max"=>20,"R"=>240,"G"=>91,"B"=>20,"Alpha"=>100);
$myPicture->setShadow(TRUE,array("X"=>1,"Y"=>1,"R"=>0,"G"=>0,"B"=>0,"Alpha"=>20));
$myPicture->drawAreaChart(array("Threshold"=>$Threshold));

在面积图中可以使用高于/低于阈值的着色。我怀疑这适用于折线图，但值得一试......

也可以用水平线表示阈值，也可以从这个例子中指出：

/* Write the thresholds */
$myPicture->drawThreshold(5,array("WriteCaption"=>TRUE,"Caption"=>"Warn Zone","Alpha"=>70,"Ticks"=>2,"R"=>0,"G"=>0,"B"=>255));
$myPicture->drawThreshold(10,array("WriteCaption"=>TRUE,"Caption"=>"Error Zone","Alpha"=>70,"Ticks"=>2,"R"=>0,"G"=>0,"B"=>255));

顺便说一句，此阈值虚线符合行（非区域）图形。