奇怪的javascript数组推送行为

Question

我编写了一个简单的代码来将查询结果操作到谷歌图表数据表的二维数组（矩阵）。 我对这种奇怪的array.push 行为感到厌烦：当我在矩阵中推送新行时，此方法会添加行，但也会更改所有先前行的值！

这是代码：

<script src="https://www.gstatic.com/charts/loader.js" type="text/javascript"></script>
<script type="text/javascript">

query 是查询中的矩阵

var qry = [[{label:'Montly', type: 'string'}, {label:'Model', type: 'string'}, {label:'total', type: 'number'}], ['12-2017','California T',parseFloat(13+13)], ['12-2017','458 Speciale',parseFloat(3+2)], ['12-2017','GTC4Lusso',parseFloat(2+6)], ['12-2017','458 Spider',parseFloat(0+1)], ['12-2017','GTC4Lusso T',parseFloat(2+0)], ['12-2017','California',parseFloat(0+2)], ['12-2017','488 Spider',parseFloat(16+7)], ['12-2017','FF',parseFloat(1+3)], ['12-2017','488 GTB',parseFloat(17+10)], ['12-2017','F12berlinetta',parseFloat(3+4)], ['12-2017','458 Italia',parseFloat(0+3)], ['12-2017','F12tdf',parseFloat(1+21)], ['12-2017','LaFerrari Aperta',parseFloat(0+1)], ['12-2017','812 Superfast',parseFloat(2+3)], ['12-2017','Portofino',parseFloat(1+1)], ['11-2017','458 Spider',parseFloat(2+4)], ['11-2017','GTC4Lusso',parseFloat(4+34)], ['11-2017','California T',parseFloat(8+15)], ['11-2017','488 GTB',parseFloat(9+12)], ['11-2017','LaFerrari',parseFloat(0+1)], ['11-2017','458 Speciale',parseFloat(2+2)], ['11-2017','GTC4Lusso T',parseFloat(0+1)], ['11-2017','FF',parseFloat(1+4)], ['11-2017','812 Superfast',parseFloat(3+1)], ['11-2017','California',parseFloat(0+3)], ['11-2017','488 Spider',parseFloat(11+8)], ['11-2017','458 Italia',parseFloat(1+5)], ['11-2017','F12tdf',parseFloat(0+1)], ['11-2017','Portofino',parseFloat(0+1)], ['11-2017','F12berlinetta',parseFloat(3+4)], ['10-2017','458 Italia',parseFloat(0+4)], ['10-2017','California T',parseFloat(9+18)], ['10-2017','California',parseFloat(0+8)], ['10-2017','812 Superfast',parseFloat(1+2)], ['10-2017','F12tdf',parseFloat(1+2)], ['10-2017','Portofino',parseFloat(2+0)], ['10-2017','488 GTB',parseFloat(8+14)], ['10-2017','FF',parseFloat(0+3)], ['10-2017','458 Spider',parseFloat(1+3)], ['10-2017','LaFerrari Aperta',parseFloat(0+1)], ['10-2017','F12berlinetta',parseFloat(5+8)], ['10-2017','458 Speciale',parseFloat(3+2)], ['10-2017','488 Spider',parseFloat(9+7)], ['10-2017','GTC4Lusso',parseFloat(2+4)], ['9-2017','California',parseFloat(0+4)], ['9-2017','458 Speciale Aperta',parseFloat(1+0)], ['9-2017','FF',parseFloat(3+6)], ['9-2017','812 Superfast',parseFloat(2+1)], ['9-2017','458 Italia',parseFloat(1+3)], ['9-2017','GTC4Lusso',parseFloat(2+6)], ['9-2017','F12tdf',parseFloat(1+0)], ['9-2017','LaFerrari',parseFloat(0+1)], ['9-2017','488 GTB',parseFloat(18+13)], ['9-2017','458 Spider',parseFloat(3+2)], ['9-2017','F12berlinetta',parseFloat(4+10)], ['9-2017','458 Speciale',parseFloat(5+1)], ['9-2017','California T',parseFloat(23+37)], ['9-2017','488 Spider',parseFloat(11+14)], ['8-2017','FF',parseFloat(0+1)], ['8-2017','458 Spider',parseFloat(0+1)], ['8-2017','F12berlinetta',parseFloat(0+3)], ['8-2017','GTC4Lusso',parseFloat(0+6)], ['8-2017','488 GTB',parseFloat(0+1)], ['8-2017','California T',parseFloat(0+2)], ['8-2017','458 Italia',parseFloat(0+2)], ['8-2017','California',parseFloat(0+2)], ['7-2017','488 GTB',parseFloat(9+14)], ['7-2017','458 Speciale',parseFloat(1+4)], ['7-2017','California T',parseFloat(14+20)], ['7-2017','GTC4Lusso',parseFloat(1+7)], ['7-2017','California',parseFloat(1+6)], ['7-2017','458 Italia',parseFloat(1+4)], ['7-2017','458 Speciale Aperta',parseFloat(1+0)], ['7-2017','F12berlinetta',parseFloat(3+7)], ['7-2017','FF',parseFloat(2+3)], ['7-2017','458 Spider',parseFloat(1+3)], ['7-2017','488 Spider',parseFloat(10+10)], ['7-2017','F12tdf',parseFloat(0+1)], ['6-2017','488 GTB',parseFloat(7+23)], ['6-2017','458 Italia',parseFloat(2+2)], ['6-2017','812 Superfast',parseFloat(1+0)], ['6-2017','FF',parseFloat(0+3)], ['6-2017','GTC4Lusso',parseFloat(2+16)], ['6-2017','458 Spider',parseFloat(3+6)], ['6-2017','F12tdf',parseFloat(0+2)], ['6-2017','LaFerrari',parseFloat(0+1)], ['6-2017','F12berlinetta',parseFloat(4+9)], ['6-2017','458 Speciale',parseFloat(2+3)], ['6-2017','California T',parseFloat(16+18)], ['6-2017','488 Spider',parseFloat(11+14)], ['5-2017','458 Speciale',parseFloat(4+4)], ['5-2017','458 Italia',parseFloat(0+2)], ['5-2017','F12berlinetta',parseFloat(2+5)], ['5-2017','F12tdf',parseFloat(0+3)], ['5-2017','FF',parseFloat(0+1)], ['5-2017','488 GTB',parseFloat(8+13)], ['5-2017','458 Spider',parseFloat(0+2)], ['5-2017','GTC4Lusso',parseFloat(0+6)], ['5-2017','488 Spider',parseFloat(6+12)], ['5-2017','California T',parseFloat(12+19)], ];

我想从列中提取唯一模型并为折线图创建系列

function extractColumn(arr, column) {
    function reduction(previousValue, currentValue) {
        previousValue.push(currentValue[column]);
        return previousValue;
    }

    return arr.reduce(reduction, []);
}

var prima = extractColumn(qry,1);
var models = [...new Set(prima)];

使用提取列我得到第 1 列的所有值，使用扩展运算符我得到模型数组，没有重复。

var testa = [];   // the header of the matrix
var tabella = []; // the array for the DataTable

for (i=1; i<models.length; i++) {
    riga[i]=0;
}
testa.push([{label:'Montly', type: 'string'}]);
for (i=1; i<models.length; i++) {
    testa.push([{label:models[i], type:'number'}]);
} // this code create the header objects
tabella.push(testa);      //push the header into the tabella array
console.log(tabella[0]);  //this push is ok!
var mese=qry[1][0];       // first date value
var riga = [];            // array to add as row of the matrix
riga[0]=mese;             // start populating the firs row

以下代码应创建一个新行并将其附加到图表表中。 它检查查询矩阵 (qry) 每一行的日期：如果是新日期，则将创建的行附加到图表表并开始新行，否则继续创建新行。

for (i=1; i<qry.length; i++){             // iterate qry array
    if (mese!=qry[i][0]) {        // check if the date is new
        console.log(riga);                // all the created row are ok!
        tabella.push(riga);               // append the row to the array
        console.table(tabella);           // WEIRD PROBLEM: ALL THE ARRAY ROW ARE CHANGED
        mese=qry[i][0];                   // EVERY CICLE! 
        for (x=1; x<models.length; x++) {
            riga[x]=0;
        }
        riga[0]=mese;                     //reset the new row array and set the date
    } else {
        for (t=0;t<models.length;t++){
            pos = models.indexOf(qry[i][1]);
            if (pos != -1) {
                riga[pos]=qry[i][2]
                }
        }                                // this code populates the new row.
    }
}

以下代码创建图表

google.charts.load('current', {'packages':['corechart']});
google.charts.setOnLoadCallback(drawChart);
function drawChart() {
    var data = google.visualization.arrayToDataTable(tabella);

   var options = {
        title: 'Montly Trend Focus on Complaint Type',
        colors: ['#D9D904','#2A55FF','#000000'],
        backgroundColor: {fill:'#FAFAFA',strokeWidth:1},
        chartArea: {width:1800,height:380,left:70},
        curveType: 'none',
        legend: { position: 'bottom' },
        hAxis: {direction:-1},
        annotations: {
            alwaysOutside: true,
            textStyle: {
                fontSize: 12,
                bold: true,
                color: '#000000',
            }
        }
    };

    var chart = new google.visualization.LineChart(document.getElementById('line_chart'));

    chart.draw(data, options);
}

这是来自我的控制台的图像：

Answer 1

我解决了我在循环中重新声明新行的问题：

for (i=1; i<qry.length; i++){
    if (mese!=qry[i][0]) {
        tabella.push(riga);
        var riga=[];             // NEW DECLARATION
        mese=qry[i][0];
        for (x=1; x<models.length; x++) {
            riga[x]=0;
        }
        riga[0]=mese;
    }
    else {
        for (t=0;t<models.length;t++){
            pos = models.indexOf(qry[i][1]);
            if (pos != -1){riga[pos]=qry[i][2]}
        }
        }
}

希望这对其他人有用。