Having trouble with guide, tags, and Findobj

I have a situation that has me pulling out what little hair I have left. In the past, I have used findobj() to help me find handle graphics objects with unique tags. I am trying to get this to work on some new code and it is just failing, and I can't figure out why. I know I am missing something obvious, but it's been a while since I used findobj().

The story is this. I am using GUIDE to create a figure, which will then have buttons and such on it. I use the Property Inspector within Guide to call up the properties of the figure, change the background color, re-name it, and give it a tag, let's call it "Census." I then save the GUI as a .fig and .m. Now when I execute this figure, it should have the property "Tag" set to "Census". And if I use the figure tools to examine the properties, this is indeed the case.

Yet, if I do p = findobj('Tag', 'Census'), matlab returns an empty matrix.

I thought perhaps the syntax of findobj had changed, but I have some code from years ago that does exactly the same thing (tag was set originally in Guide) and when I execute the command for that window in exactly the same way, and use findobj the same way, matlab returns a figure number (which is, of course, what I want).

Anyone have any idea what is going on? I am frankly stumped. This should be a simple thing, and it works with my old code perfectly, yet the exact same thing does not work with my new figure. I've been trying to get this simple thing to work all afternoon, and now I am just frustrated beyond belief. Any help would be appreciated.

Answer 1

[Matt Fig]

GUIDE GUIs have hidden handles...

p = findall(0,'tag','Census')

P.S., you may want to switch to other methods of handle retrieval than these, such as GUIDATA. Also, you are running the GUI by calling the m-file, not by opening the figure, correct?

[Matt Fig]

Steven replied,

Yes I run the GUI from the command line. Also, findall(0,...) still returns an empty matrix. What I don't understand is why this works for my old code but not here. Everything is done the same way as far as I can tell. I used GUIDE to create both windows. I set the tag for both windows (one years ago, one today) using the property inspector. I saved as both .fig and .m. I execute the .m from the command line. In one case, findobj('tag',...) works, in the other findobj('tag',...) returns an empty matrix. The syntax is the same. The process for creating the windows in GUIDE was the same. So I am baffled. Why is one working but not the other?

[Matt Fig]

Give this a try.

Run the GUI that is giving you trouble by asking for the handle.

H = mygui;  % For example.
get(get(H,'children'),'tag')

This will show you what the tags really are.

[John]

Hey guys,

I have the same problem as above! None of your options works Matt:( i really dont know whats the problem....

I have one MainGui and a SubGui that is opened by the user from the MainGui. Nevertheless i dont find SubGui when i search for children of MainGui. But i think i dont use the children function in a correct way. HOw can i do it? the tag 'try1_' is from my MainGui. I find this one but not the other one from SubGui.

   H = findobj('Tag','try1_')
   handlesH = guidata(H)
   allchild(H)

i get this"

ans =

      9.0033
      8.0033
      7.0033
      6.0033
      5.0033
      0.0033
    197.0032
    195.0032
    190.0032
    188.0032
    185.0032
    183.0032
    181.0032
    174.0032

What is the problem? I am very glad for your help!

Best regards, John

Answer 2

[Feng Cheng]

Hey guys,

Is this issue fixed? I think i have the same problem. The same code is really on again and off again. e.g., the following phrase sometime will throw out error 'Unable to perform assignment because the indices on the left side are not compatible with the size of the right side' because `findobj` return empty.

 item = findobj(gcf, 'Tag', 'flow_listbox')

So i replace `findobj` with the following phrase. and it works well.

 item = handles.flow_listbox

But i really want to know what's wrong with `findobj`.