You cannot overwrite the contents of a column with a different data type.
You could insert a new column, fill it with dates, and then delete the old
column:
data.insertColumn(1, 'date', 'date');
for (var i = 0; i < data.getNumberOfRows(); i++) {
var dateString = data.getValue(row, 0).toString();
var year = dateString.substring(0, 4);
var month = dateString.substring(4, 2); // javascript uses 0-indexed
months (ie, January is 0 not 1), so you may need to subtract 1 from this if
you haven't already accounted for it
var day = dateString.substring(6, 2);
data.setValue(1, i, new Date(year, month, day));
}
data.removeColumn(0);
You can then format the date column with a DateFormatter.
On Monday, April 7, 2014 5:57:01 PM UTC-4, cyb wrote:
>
> Hi,
>
> i want not add new columns.. is there no way that i can take the 'date'
> column from the DataTable and parse it to a column with type =date ? i
> thought i can overwrite values in a DataTable?
>
> data = new google.visualization.arrayToDataTable([
> ['date','New York','Austin','San
> Francisco','Country','Popularity'],
> ['20111001',2,3,15,'Germany',200],
> ['20111002',5,6,19,'Brazil',400],
> ['20111003',8,9,23,'United States',300],
> ['20111004',11,12,35,'RU',700]
> ];)
>
> at the moment i have this data, and the "date" colum is parsed to a
> number..
>
> can i not write a calc function that does the same as your code with the
> dataView ?
>
> and second questions:
>
> yout have set "return {v: date, f: formatter.formatValue(date)};" for
> what is v:date ? for the formatted value? because you have already set the
> type to date with "dataView.setColumns([{
> type: 'date',...."
>
>
>
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