动态计算分组聚合

Question

我有3栏-总计、计数-每一列=总数/计数；

使用光滑的网格和总结每一列是不正确的，因为加权平均数。

 Total     Count      Each
 4         2          2
 3         6          .5
---------------------------
 7         8          2.5 (incorrect )

7/8 = .875

 7         8          .875 (is correct if I take the sum(total) / sum(count) as an aggrigate)

我使用的是

new Slick.Data.Aggregators.Sum("Total")
new Slick.Data.Aggregators.Sum("Each")

但是，我怎样才能计算出这2的总和，并创造出第三个总和。

Answer 1

这是一个有点棘手和处理网格的通常方式，但我设法做到这一点，把你的计算中的一些全局变量。

// global variables
var myGlobalCount = 0; 
var myGlobalTotal = 0;


function sumTotalsFormatter(totals, columnDef) {
    // keep the total inside the global variable 
    // this piece of code is new and outside of typical SlickGrid implementation
    switch(columnDef.field){
        case 'Count':   
            myGlobalCount = parseFloat(totals.sum[columnDef.field]);
            break;
         case 'Total':   
            myGlobalTotal = parseFloat(totals.sum[columnDef.field]);
            break;
    }

    // display as usual the Sum of whichever column that is
    // there is nothing new here, it's the simple SlickGrid sum display
    return '<span style="font-weight:bold;">'+totals.sum[columnDef.field]+'</span>';
}


function eachCalculation(totals, columnDef) {
    // VERY IMPORTANT.... The Each column has to come AFTER the other columns of Count & Total
    // the reason is simple we will use the global variables and they have to be filled prior to use them for calculation

    // do calculation with globale variables
    var eachTotal = myGlobalTotal / myGlobalCount;

    // display the calculation on the Title so that when you hover the total it will display calculation
    var titleText = "Total / Sum = " + eachTotal + " :: " + myGlobalTotal + " / " + myGlobalCount + " = " + eachTotal;

    return '<span style="font-size:9pt; font-weight:bold; color:gree" title="'+titleText+'">'+eachTotal+'</span>';
}

// Your columns definition will include your custom groupTotalsFormatter
columns1 = [
    {id:"Total", name:"Total", field:"Total", width:75, groupTotalsFormatter:sumTotalsFormatter},
    {id:"Count", name:"Count Part", field:"Count", width:100, groupTotalsFormatter:sumTotalsFormatter},
    {id:"Each", name:"Each", field:"Each", width:70, groupTotalsFormatter:eachCalculation}
];

我编辑了我的部分代码，没有用您的代码进行测试，但是它应该work...try出来，如果您有问题请告诉我.祝好运