php – 谷歌图表 – 绘制空值

问题是图表将NULL值绘制为0并且看起来非常难看.

我最好的猜测是我以错误的方式创建json,而我真正想要的输出是{“v”：}而不是{“v”：“”}.

折线图现在：

我想要的是：

PHP代码

$reports['cols'][] = array(label => "Time",type => "string");
        $reports['cols'][] = array(label => "Today",type => "number");
        $reports['cols'][] = array(label => "Yesterday",type => "number");
        $reports['cols'][] = array(label => "Budget",type => "number");

            //Some mysql code that populates values ($today,$yesterday,$budget)

        $rows = array();
        for($i=10; $i <= 21; $i++){

            $temp = array();
            $temp[] = array('v' => (int) $i);
                    //Format string will return "" and not "0" if value is blank
            $temp[] = array('v' => (string) $today["$i"]);
            $temp[] = array('v' => (string) $yesterday["$i"]);
            $temp[] = array('v' => (string) $budget);
            $rows[]['c'] = $temp;
        }

        $reports['rows'] = $rows;
        $string=json_encode($reports);
        echo $string;

php的输出：

{
    "cols":[
        {"label":"Time","type":"string"},{"label":"Today","type":"number"},{"label":"Yesterday",{"label":"Budget","type":"number"}
    ],"rows":[
        {"c":[{"v":10},{"v":"0"},{"v":"90000"}]},{"c":[{"v":11},{"v":"22491"},{"v":"7420"},{"c":[{"v":12},{"v":""},{"v":"50082"},{"c":[{"v":13},{"v":"91660"},{"c":[{"v":14},{"v":"109204"},{"c":[{"v":15},{"v":"115280"},{"c":[{"v":16},{"v":"111853"},{"c":[{"v":17},{"v":"87368"},{"c":[{"v":18},{"v":"33063"},{"c":[{"v":19},{"v":"14903"},{"c":[{"v":20},{"v":"1441"},{"c":[{"v":21},{"v":"90000"}]}
    ]
}

Javascript

google.load("visualization","1",{packages:["corechart"]});
    google.setOnLoadCallback(drawChart);
    function drawChart() {

    var jsonData = $.ajax({
        url: "functions/load.php?q=salesChart",dataType:"json",async: false
    }).responseText;

    // Create our data table out of JSON data loaded from server.
    var data = new google.visualization.DataTable(jsonData);

    var options = {
        title: 'Money / Hour',colors: ['#4BA15A','#45559D','red'],legend: {position: 'top'},lineWidth: 2,pointSize: 3,fontName: 'Helvetica',fontSize: 10,interpolateNulls: false,backgroundColor: {strokeWidth: 1},chartArea: {left: 70,top: 60,width: "85%",height: "70%"} 
    };

    var chart = new google.visualization.LineChart(document.getElementById('chart_div'));
    chart.draw(data,options);
}