Including a value inside an annotation

I am trying to include a number which changes inside a recurring annotation.

This works - the number 48 is hard-coded:

annotation('textbox',[0.42  0.864 0.1 0.1],'String','L. St. Lawrence - INCREASE IN ISI (n=48)','EdgeColor','none',    'FontSize',12,'Color','black','FontWeight','bold')

This does not (note the insertion of a number q, which has been pre-allocated a value of 48):

annotation(['textbox',[0.42  0.864 0.1 0.1],'String','L. St. Lawrence - INCREASE IN ISI (n=',num2str(q),')','EdgeColor','none','FontSize',12,'Color','black','FontWeight','bold'])

The error I get is:

Error using annotation

First argument must be a valid annotation type or a handle to a figure, uipanel, or uitab.

Thanks for helping!

Answer 1

[Walter Roberson]

You have

annotation(['textbox',[0.42  0.864 0.1 0.1],'String','L. St. Lawrence - INCREASE IN ISI (n=',num2str(q),')','EdgeColor','none','FontSize',12,'Color','black','FontWeight','bold'])

This includes a [] expression that must be evaluated first, and the result of the [] expression will be passed as a parameter to annotation()

The [] expression is

['textbox',[0.42  0.864 0.1 0.1],'String','L. St. Lawrence - INCREASE IN ISI (n=',num2str(q),')','EdgeColor','none','FontSize',12,'Color','black','FontWeight','bold']

which asks to [] together characters and numeric values.

When you [] together characters and numeric values, the numeric values are converted using char() . Note that char() of a numeric value is not the printable representation of the numeric value. If you char(65) for example you do not get '65' (the character for the digit 6 followed by the character for the digit 5). Instead, char() does a uint16() of the provided value (except it rounds down) and then treats the resulting integer as a Unicode Code Point. char(65) requests the 66'th Unicode Code Point (they start at 0) which happens to be the character 'A'

So ['textbox',[0.42 0.864 0.1 0.1]] would be the same as [['textbox',char([0.42 0.864 0.1 0.1])] which would be the same as ['textbox',char(uint16(floor([0.42 0.864 0.1 0.1])))] which would be ['textbox', char(uint16([0 0 0 0]))] which would be ['textbox', char(0), char(0), char(0), char(0)] so would be a character vector that started with 'textbox' and was then 4 binary characters.

This is clearly no what you want.

What you might have wanted might have been

annotation('textbox',[0.42  0.864 0.1 0.1],'String',['L. St. Lawrence - INCREASE IN ISI (n=',num2str(q),')'],'EdgeColor','none','FontSize',12,'Color','black','FontWeight','bold'])

which leaves 'textbox' and the double precision numbers as separate parameters, and constructs a character vector from the 'L. St. Lawrence' and so on through to the ')' and passes that as the parameter after 'String'

So your [] were out of place.

These days I would probably suggest

annotation('textbox',[0.42  0.864 0.1 0.1],'String',"L. St. Lawrence - INCREASE IN ISI (n="+q+")",'EdgeColor','none','FontSize',12,'Color','black','FontWeight','bold'])

when you use "" objects those are string() objects whereas '' objects are character vectors. string() objects define a + operation that converts numeric values to representable text and append that to the end of the string object.

[Paul Barrette]

Thanks a lot, @Walter Roberson. Both solutions worked, notwithstanding an extra ']' at the end that I had to remove - the corrected versions are:

annotation('textbox',[0.42 0.864 0.1 0.1],'String',['L. St. Lawrence - INCREASE IN ISI (n=',num2str(q),')'],'EdgeColor','none','FontSize',12,'Color','black','FontWeight','bold')

and

annotation('textbox',[0.42 0.864 0.1 0.1],'String',"L. St. Lawrence - INCREASE IN ISI (n="+q+")",'EdgeColor','none','FontSize',12,'Color','black','FontWeight','bold')

Tx also for the explanations - after a careful read, I understand where the problem was and why the solution offered by @Sulaymon Eshkabilov worked. Your input has turned into a mini-lecture - much appreciated!

Answer 2

[Sulaymon Eshkabilov]

Here is the solution to this issue:

q = 48;
DIM = [0.42  0.864 0.1 0.1];
STR = strcat('L. St. Lawrence - INCREASE IN ISI (n= ', num2str(q), ' )');
annotation('textbox',DIM,'String',STR,'FitBoxToText','on','EdgeColor','none','FontSize',12,'Color','black','FontWeight','bold');

[Paul Barrette]

This works! Based on why I've tried so far, I think the 'FitBoxToText' was the key element (though I'm not sure why).

[Sulaymon Eshkabilov]

Most welcome -sir!

[Paul Barrette]

Hi @Sulaymon Eshkabilov, I hope you will not mind too much my switching to @Walter Roberson's solutions. They are closer to what my code needs, plus the extra value provided.