Change tooltip data in Google Charts - charts

Question

I have column google charts. (using https://www.google.com/jsapi)
Vertical axis for count of bananas(for example)
Horizontal axis for dates
so, each my column tooltip looks like:
20.02.2011
Bananas: 3
I need to replace 20.02.2011 on some my text on each column.
Is it possible?
UPD
I need to replace 20.02.2011 on some my text on each column.
But dates on Horizontal axis should stay as they are.

Answer 1

The best way to do it without changing your actual data points is via the tooltip option. As an example copy the following code to google's visualization playground.
function drawVisualization() {
data = new google.visualization.DataTable()
data.addColumn('string', 'Date');
data.addColumn('number');
data.addColumn({type:'string',role:'tooltip'});
data.addRow();
base = 10;
data.setValue(0, 0, 'Datapoint1');
data.setValue(0, 1, base++);
data.setValue(0, 2, " This is my tooltip1 ");
data.addRow();
data.setValue(1, 0, 'Datapoint2');
data.setValue(1, 1, base++);
data.setValue(1, 2, "This is my second tooltip2");
// Draw the chart.
var chart = new google.visualization.BarChart(document.getElementById('visualization'));
chart.draw(data, {legend:'none', width:600, height:400});
}

Answer 2

One option is to change the horizontal axis with the text that you want.
For ex.
In this sample code http://code.google.com/apis/ajax/playground/?type=visualization#bar_chart
Chart URL
If you want to replace year with your custom text then change
var years = [2003, 2004, 2005, 2006, 2007, 2008];
to either
var years = ["a", "b", "c", "d", "e", "f"];
or
var years = ["2003:a", "2004:b", "2005:c", "2006:d", "2007:e", "2008:f"];