I'm using a DataView object to only select specific columns from a
DataTable and draw then on a chart. I want to be able to create new columns
in the DataView that are functions of the values already in the DataView.
So far i have managed to produce a cumulative number from the code below
(copy into google playground
https://code.google.com/apis/ajax/playground/?type=visualization#table)
however i want to know the column id of the column created in the
dataview/pass the column id as well as the row number. For example I
ultimately want to be able to have this:
| Number 1 | Number 2 | Cumulative Number 1 | Cumulative
Number 2 | Other functions
| 4 | 3 | 4
| 3 |
| 2 | 1 | 6
| 4 |
| 1 | 4 | 7
| 8 |
| 0 | 2 | 7
| 10 |
| 3 | 1 | 10
| 11 |
| 5 | 0 | 15
| 11 |
> // Create and populate the data table.
> var data = google.visualization.arrayToDataTable([
> ['Name', 'Foo Distance', 'Bar Distance', 'Smokes'],
> ['Tong Ning mu', 4, 3, true],
> ['Huang Ang fa', 2, 6, false],
> ['Huang Ang fa', 1, 0, false],
> ['Huang Ang fa', 0, 2, false],
> ['Huang Ang fa', 3, 5, false],
> ['Huang Ang fa', 5, 7, false],
> ['Huang Ang fa', 8, 2, false],
> ['Huang Ang fa', 0, 1, false],
> ['Teng nu', 2, 0, true]
>
> ]);
>
> var dataview = new google.visualization.DataView(data);
>
> dataview.setColumns([1,2,{calc:cumulative, type:'number', label:'Foo ::
> Total Distance'}, {calc:cumulative, type:'number', label:'Bar :: Total
> Distance'}]);
>
> function cumulative(dataTable, rowNum){
> if(rowNum > 0){
> return (dataview.getValue(rowNum-1, 2) + dataTable.getValue(rowNum, 1)
> );
> }
> return dataTable.getValue(rowNum, 1);
> }
> // Create and draw the visualization.
> visualization = new google.visualization.Table(document.getElementById(
> 'table'));
> visualization.draw(dataview, null);
> }
>
function drawVisualization() {
The only way I could do this without column id is have a cumulative
function for each column, however this needs to be dynamic.
tl;dr Basically i need a way to pass the column id into the calc function
when calculating new columns.
i.e.
dataview.setColumns([1,2,{calc:
> cumulative(column_id_to_calc_cumulative_from), type:'number', label:'Foo
> :: Total Distance'}]);
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