Set an existing column to tooltip in google visualization api?

Question

Is it possible to set an existing column to be used as a html tooltip for a bar chart in google api without having to perform the following:

data.addColumn({type:'string',role:'tooltip'});

then adding the tooltip specific fields after converting the data to a datatable? Is there something like a:

data.setColumn(2, {type:'string',role:'tooltip'})

such that I dont have to adda new one? Does such a function exist?

My data is currently like this:

[
["Name", "Number", "Tooltip"],
["James", 1, "Tooltip for James"],
["Kyle", 2, "Tooltip for Kyle"]
]

Answer 1

使用DataTable＃setColumnProperty方法设置角色：

data.setColumnProperty(2, 'role', 'tooltip');