%% Convert Date Value to Equivalent Numeric Value
% Convert a date value to the equivalent numeric value in order to set the Position property of a text object.
% Create a plot with dates along the x-axis. Add a text description to the fourth data point and return the text object.

t = datetime(2015,1,1:10);
y = [.2 .3 .5 .2 .8 .2 .3 .1 .3 .4];
plot(t,y,'-o')
txt = text(t(4),y(4),'My text');

%
% Change the position of the text to the sixth data point by setting the Position property of the text object. Since the Position property accepts only numeric values, convert the datetime value at the sixth data point to the equivalent numeric value.

ax = gca;
x6 = ruler2num(t(6),ax.XAxis);
txt.Position = [x6 y(6)];

% Copyright 2012 The MathWorks, Inc.