[英]calculate average in a table using javascript
所以我想要的是獲得特定列的平均值。 我想獲得 PO1 到 PO9 列的平均值。 我想使用 javascript。 所以請大家幫幫我。 謝謝
這是我的 html 表:
<table id="view_classlist" class="table table-striped table-bordered dataTable no-footer">
<thead>
<tr>
<th><center>Student ID </i></center></th>
<th><center>Name </i></center></th>
<th><center>PO 1</center></th>
<th><center>PO 2</center></th>
<th><center>PO 3</center></th>
<th><center>PO 4</center></th>
<th><center>PO 5</center></th>
<th><center>PO 6</center></th>
<th><center>PO 7</center></th>
<th><center>PO 8</center></th>
<th><center>PO 9</center></th>
</tr>
</thead>
<tbody>
<tr>
<td><center>111</center></td>
<td><center>John</center></td>
<td><center>1.1</center></td>
<td><center>2.0</center></td>
<td><center>3.0</center></td>
<td><center>2.7</center></td>
<td><center>1.9</center></td>
<td><center>1.2</center></td>
<td><center>1.1</center></td>
<td><center>1.3</center></td>
<td><center>1.2</center></td>
</tr>
<tr>
<td><center>112</center></td>
<td><center>Mae</center></td>
<td><center>1.2</center></td>
<td><center>2.0</center></td>
<td><center>1.2</center></td>
<td><center>1.2</center></td>
<td><center>1.3</center></td>
<td><center>1.5</center></td>
<td><center>1.4</center></td>
<td><center>1.2</center></td>
<td><center>3.0</center></td>
</tr>
<tr>
<td><center>113</center></td>
<td><center>Jerry</center></td>
<td><center>1.1</center></td>
<td><center>1.2</center></td>
<td><center>3.0</center></td>
<td><center>2.7</center></td>
<td><center>1.2</center></td>
<td><center>1.6</center></td>
<td><center>1.2</center></td>
<td><center>2.3</center></td>
<td><center>1.2</center></td>
</tr>
<tfoot>
<td colspan="2"><center>Average</center></td>
<td><center></center></td>
<td><center></center></td>
<td><center></center></td>
<td><center></center></td>
<td><center></center></td>
<td><center></center></td>
<td><center></center></td>
<td><center></center></td>
<td><center></center></td>
</tfoot>
</tbody>
這是一種方法:
var table = document.getElementById('view_classlist'),
rows = table.getElementsByTagName('tbody')[0].getElementsByTagName('tr'),
footer = table.getElementsByTagName('tfoot')[0];
// for each column that must be treated
for(var i=2; i<11; i++){
var sum = numOfValues = 0;
// add each row's value
for(numOfValues=0, l=rows.length; numOfValues<l; numOfValues++){
sum += parseFloat(
rows[numOfValues].getElementsByTagName('td')[i]
.getElementsByTagName('center')[0]
.innerHTML
);
}
// calculate the average
var avg = sum / numOfValues;
// insert it in the corresponding TD (rounded to 2 decimals)
footer.getElementsByTagName('td')[i-1].innerHTML = Math.round(avg * 100) / 100;
}
我有一個名為html5csv.js的庫,除其他外,它可以抓取表格並在瀏覽器端 JS 中添加計算。
首先,讓我們稍微清理一下表格以消除單元格中像<center>
這樣的非數字數據:
<table id="view_classlist" class="table table-striped table-bordered dataTable no-footer">
<thead>
<tr>
<th>Student ID </i></th>
<th>Name </i></th>
<th>PO 1</th>
<th>PO 2</th>
<th>PO 3</th>
<th>PO 4</th>
<th>PO 5</th>
<th>PO 6</th>
<th>PO 7</th>
<th>PO 8</th>
<th>PO 9</th>
</tr>
</thead>
<tbody>
<tr>
<td>111</td>
<td>John</td>
<td>1.1</td>
<td>2.0</td>
<td>3.0</td>
<td>2.7</td>
<td>1.9</td>
<td>1.2</td>
<td>1.1</td>
<td>1.3</td>
<td>1.2</td>
</tr>
<tr>
<td>112</td>
<td>Mae</td>
<td>1.2</td>
<td>2.0</td>
<td>1.2</td>
<td>1.2</td>
<td>1.3</td>
<td>1.5</td>
<td>1.4</td>
<td>1.2</td>
<td>3.0</td>
</tr>
<tr>
<td>113</td>
<td>Jerry</td>
<td>1.1</td>
<td>1.2</td>
<td>3.0</td>
<td>2.7</td>
<td>1.2</td>
<td>1.6</td>
<td>1.2</td>
<td>2.3</td>
<td>1.2</td>
</tr>
</tbody>
然后按任務平均,我們將添加這個加載了 jQuery 和 html5csv.js 的 JS:
CSV.begin('#view_classlist')
.call(function(next){
var rows = this.data.rows;
var lCol=rows[0].length;
var firstRow = 1;
var lRow = this.data.rows.length;
var colAvg = ['Average',''];
for(var col=2; col<lCol; col++){
colAvg[col] = 0.0;
for(var row=1; row<lRow; row++)
colAvg[col] += rows[row][col]/(lRow-1);
}
this.data.rows.push(colAvg);
})
.table("tableWithAvg")
.go();
這從從原始表中抓取數據開始,調用用戶定義的函數將列平均值添加到表中,然后輸出一個 ID 為“tableWithAvg”的新表
為了按學生求平均值,我們想要添加一列,並且在html5csv.js Wiki 中有一個名為appendCol
的 CSV 助手。
以下與 html5CSV.js 庫一起使用以按學生求平均值:
CSV.begin('#view_classlist')
.appendCol("Avg", function(index, row){
var sum = 0.0;
for(var k in row){
if (k.indexOf('PO')>=0) sum+=row[k];
}
return sum/9;
}, true)
.table("tableWithAvg")
.go();
您還可以使用 jquery 獲取 DOM 元素值,然后將其相加。
<html>
<script>
var total = 0;
$('.data').each(function(){
total += parseFloat((this).val());
});
console.log(total);
</script>
<body>
<div class="data"><td>1</td></div>
<div class="data"><td>2</td></div>
</body>
</html>
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