num = ruler2num(data,ruler)
converts the values in data to numeric values. The
ruler input indicates the ruler associated with
data, which determines how to map the values to the
corresponding numeric values. The output num is the same size as
the input data.
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.
Ruler associated with the input data, specified as a
DatetimeRuler, DurationRuler,
NumericRuler, or GeographicRuler
object. Specify the ruler object using the XAxis,
YAxis, or ZAxis property of the
Axes object. For
example:
ax = gca;
num = ruler2num(data,ax.XAxis)
If you specify a NumericRuler object and the input
data is not numeric, then the output
num is determined
by:
num = full(double(data))
If you specify a GeographicRuler object, then the
output num is equal to the input
data.