I am currently developing a basic image processing application on MATLAB. I have to implement undo to previous state feature. I searched net there is uiundo but it only undos GUI actions. Is there a simple command to undo. Thanks.
If you have plenty of memory to spare, you could store all of your program states in a structure and then push this structure into a circular buffer. The number of elements in the buffer would determine the number of levels of undo.
It seems to me that you would have to implement your own multi-level (or one-level) undo by using the Command pattern.
This would require you to wrap your operations into objects that contain the logic to perform the action and to restore the state. No silver bullet, hard work needed.
General undo will be complicated, but if you are only interested in saving the state of MATLAB variables and returning to a saved state, this might be one possible solution:
save_state.m:
SavedStateFolder = '/home/user/matlab_saved_states_folder/';
save([ SavedStateFolder, 'saved_state_', sprintf('%06d', (size(dir(SavedStateFolder), 1) - 1)) ]);
fprintf('state saved in saved_state_%s.mat\n', sprintf('%06d', (size(dir(SavedStateFolder), 1) - 2)));
undo_index.m:
function undo_index()
SavedStateFolder = '/home/user/matlab_saved_states_folder/';
FilesStruct = dir(SavedStateFolder);
LastSavedStateIndex = size(FilesStruct, 1) - 2;
if (LastSavedStateIndex < 1)
fprintf('No saved states available.\n');
else
fprintf('Index of last saved state is %06d\n', LastSavedStateIndex);
end
return
undo.m:
SavedStateFolder = '/home/user/matlab_saved_states_folder/';
load([ SavedStateFolder, 'saved_state_', sprintf('%06d', input('Enter saved state index ')) ]);
Then you can use save_state to save the state of MATLAB variables or you can even prefix all your commands with save_state; if you want to keep track of all changes. When you want to return to a previous state of variables, you can run undo_index to find out the index of last saved state and then you can run undo and input the index given by undo_index, or alternatively any smaller positive integer to return to an earlier state of variables. The first saved state file will be named saved_state_000001.mat, then saved_state_000002.mat and so on... Note that save_state saves everything to disk, so using SSD or RAM disk might be a good idea if you want to try this in a loop with a lot of data. Note also that the previous content of variable called SavedStateFolder is lost when you run save_state or undo. To avoid this, you can replace all instances of SavedStateFolder in save.state.m and undo.m with hard-coded folder names, for example:
save_state.m:
save([ '/home/user/matlab_saved_states_folder/', 'saved_state_', sprintf('%06d', (size(dir('/home/user/matlab_saved_states_folder/'), 1) - 1)) ]);
fprintf('state saved in saved_state_%s.mat\n', sprintf('%06d', (size(dir('/home/user/matlab_saved_states_folder/'), 1) - 2)));
undo.m:
load([ '/home/user/matlab_saved_states_folder/', 'saved_state_', sprintf('%06d', input('Enter saved state index ')) ]);
Note also that save_state, undo_index and undo assume that in SavedStateFolder there are no other files except ., .. and saved_state_*.mat files. Also the number of saved_state_*.mat files and the running index to be saved is found out this way, so if you delete some previous saved_state_*.mat files without eg. creating equal number of empty files to replace them, the counts don't match and save_state might save the state on top of an already existing saved state file.
Related
I'm working on a vector layer where I have to merge all n+i [id] attributes into entity(n)[id] where entities(n+i)[id] equals the entity(n)[id], then delete all n+i entities.
All works fine but I call several times startEditing functions before commiting changes, and my question is: does calling commitChanges closes startEditing, or does it let it opened, like if it was a file descriptor or a pointer which we needed to free after the job's done?
The code is:
olayer.startEditing()
olayer.changeAttributeValue(n,id_obj,id_obj_sum,NULL,True)
olayer.commitChanges()
olayer.startEditing()
i= i-1
while i >=1:
olayer.deleteFeature(n+i)
i=i-1
olayer.commitChanges()
As you can see, we call several times olayer.startEditing, even more because all that code is in while body...
So will that spawn hordes of startEditing "pointers" or will it just continuously set the olayer editable status as "open to edition" ?
Actually the code works, but it's painfully slow, is this the reason why ?
By and large, you should not start the edit mode more than once in your layer.
You can commit at the end of all your changes to the layer, so that your modifications stay in an edit buffer in the meantime.
QgsVectorLayer.commitChanges() can let the edit mode open if you pass a False as parameter (the parameter is called stopEditing, see the docs). Like this:
# If the commit is sucessful, let the edit mode open
layer.commitChanges(False)
Also, have a look at the with edit(layer): syntax in the QGIS docs. Using such syntax you avoid starting/committing/closing the edit mode, QGIS does it for you.
with edit(layer):
# All my layer modifications here
# When this line is reached, my layer modifications are already committed.
I am trying to get EDS spectra on every scanned pixel using STEM.
I am using the EDSStartAcquisition( 2048, 10,fexposure*2, 1) command and
I have attached the following simple listener object into the shown 1D spectrum image:
string messagemap = "data_value_changed:MyImageAction"
Class MyListenerClass1
{
String event_desc;
MyListenerClass1(Object self); //Result("\n");
~MyListenerClass1(Object self);// Result("\n");
Void MyImageAction(Object self, Number e_fl, Image Img)
{
ImageGetEventMap().DeconstructEventFlags( e_fl, event_desc )
Result(GetTime(1)+": Image message : " + event_desc + " 0x" + Binary(e_fl) + "\n" )
}
}
ListenerID1 = EDSIm.ImageAddEventListener( Listener1, messagemap)
Since speed is the issue here, I figured to try the continuous mode of the EDS acquisition. But then I would need to listen which counts belong to each scanned pixel. The following topic (How to getting acquired frames at full speed ? - Image Event Listener does not seem to be executing after every event) shows how to listen to the last pixel change of an image. But what would be the fastest way to directly see which slice of the 1D spectrum has changed on every event? Without going through every slice...
thanks in advance!
An images' data_value_changed is fired whenever a) an image locker (the object that ensures there is single access to the memory) is released, or b) a specific update-call is made in the code.
As such, when a cumulative EDS spectrum is acquired, the whole array gets "locked", then modified (on one or more positions) and then 'updated'. There is no specific information carried on where the array was modified.
Therefore, the only way to find out where the spectrum changed is by comparing a copy of the "before" with the "now" - which is not super efficient.
I'm a student learning to use MATLAB. For an assignment, I have to create a simple state machine and collect some results. I'm used to using Verilog/Modelsim, and I'd like to collect data only when the state machine's output changes, which is not necessarily every time/sample period.
Right now I have a model that looks like this:
RequestChart ----> ResponseChart ----> Unit Delay Block --> (Back to RequestChart)
| |
------------------------> Mux --> "To Workspace" Sink Block
I've tried setting the sink block to save as "Array" format, but it only saves 51 values. I've tried setting it to "Timeseries", but it saves tons of zero values.
Can someone give me some suggestions? Like I said, MATLAB is new to me, please let me know if I need to clarify my question or provide more information.
Edit: Here's a screen capture of my model:
Generally Simulink will output a sample at every integration step. If you want to only output data when a particular event occurs -- in this case only when some data changes -- then do the following,
run the output of the state machine into a Detect Change block (from the Logic and Bit Operations library)
run that signal into the trigger port of a Triggered Subsystem.
run the output of the state machine into the data port of the Triggered Subsystem.
inside the triggered subsystem, run the data signal into a To Workspace block.
Data will only be saved at time point that the trigger occurs, i.e. when your data changes.
In your Simulink window, make sure the Relative Tolerance is small so that you can generate many more points in between your start and ending time. Click on the Simulation option at the top of the window, then click on Model Configuration Parameters.
From there, change the Relative Tolerance to something small... like 1e-10. After that, try running your simulation again. You should have a lot more points in your output array that you can now save.
I am looking for a way to save 'everything' in the matlab session when it is stopped for debugging.
Example
function funmain
a=1;
if a>1
funsub(1)
end
funsub(2)
end
function funsub(c)
b = c + 1;
funsubsub(c)
end
function funsubsub(c)
c = c + 2; %Line with breakpoint
end
When I finally reach the line with the breakpoint, I can easily navigate all workspaces and see where all function calls are made.
The question
How can I preserve this situation?
When debugging nested programs that take a long time to run, I often find myself waiting for a long time to reach a breakpoint. And sometimes I just have to close matlab, or want to try some stuff and later return to this point, so therefore finding a way to store this state would be quite desirable. I work in Windows Server 2008, but would prefer a platform independant solution that does not require installation of any software.
What have I tried
1. Saving all variables in the workspace: This works sometimes, but often I will also need to navigate other workspaces
2. Saving all variables in the calling workspace: This is already better as I can run the lowest function again, but may still be insufficient. Doing this for all nested workspaces is not very convenient, and navigating the saved workspaces may be even worse.
Besides the mentioned inconveniences, this also doesn't allow me to see the exact route via which the breakpoint is reached. Therefore I hope there is a better solution!
Code structure example
The code looks a bit like this
function fmain
fsub1()
fsub2()
fsub3()
end
function fsub1
fsubsub11
fsubsub12
...
fsubsub19
end
function fsub2
fsubsub21
fsubsub22
...
fsubsub29
end
function fsub3
fsubsub31
fsubsub32
...
fsubsub39
end
function fsubsub29
fsubsubsub291
fsubsubsub292% The break may occur in here
...
fsubsubsub299
The break can of course occur anywhere, and normally I would be able to navigate the workspace and all those above it.
Checkpointing
What you're looking to implement is known as checkpointing code. This can be very useful on pieces of code that run for a very long time. Let's take a very simple example:
f=zeros(1e6,1);
for i=1:1e6
f(i) = g(i) + i*2+5; % //do some stuff with f, not important for this example
end
This would obviously take a while on most machines so it would be a pain if it ran half way, and then you had to restart. So let's add a checkpoint!
f=zeros(1e6,1);
i=1; % //start at 1
% //unless there is a previous checkpoint, in which case skip all those iterations
if exist('checkpoint.mat')==2
load('checkpoint.mat'); % //this will load f and i
end
while i<1e6+1
f(i) = g(i) + i*2+5;
i=i+1;
if mod(i,1000)==0 % //let's save our state every 1000 iterations
save('checkpoint.mat','f','i');
end
end
delete('checkpoint.mat') % //make sure to remove it when we're done!
This allows you to quit your code midway through processing without losing all of that computation time. Deciding when and how often to checkpoint is the balance between performance and lost time!
Sample Code Implementation
Your Sample code would need to be updated as follows:
function fmain
sub1done=false; % //These really wouldn't be necessary if each function returns
sub2done=false; % //something, you could just check if the return exists
sub3done=false;
if exist('checkpoint_main.mat')==2, load('checkpoint_main.mat');end
if ~sub1done
fprintf('Entering fsub1\n');
fsub1()
fprintf('Finished with fsub1\n');
sub1done=true;
save('checkpoint_main.mat');
end
if ~sub2done
fprintf('Entering fsub2\n');
fsub2()
fprintf('Finished with fsub2\n');
sub2done=true;
save('checkpoint_main.mat');
end
if ~sub3done
fprintf('Entering fsub3\n');
fsub3()
fprintf('Finished with fsub3\n');
sub3done=true;
save('checkpoint_main.mat');
end
delete('checkpoint_main.mat');
end
function fsub2
subsub21_done=false;subsub22_done=false;...subsub29_done=false;
if exist('checkpoint_fsub2')==2, load('checkpoint_fsub2');end
if ~subsub21_done
fprintf('\tEntering fsubsub21\n');
fsubsub21
fprintf('\tFinished with fsubsub21\n');
subsub21_done=true;
save('checkpoint_fsub2.mat');
end
...
if ~subsub29_done
fprintf('\tEntering fsubsub29\n');
fsubsub29
fprintf('\tFinished with fsubsub29\n');
subsub29_done=true;
save('checkpoint_fsub2.mat');
end
delete('checkpoint_fsub2.mat');
end
function fsubsub29
subsubsub291_done=false;...subsubsub299_done=false;
if exist('checkpoint_fsubsub29.mat')==2,load('checkpoint_fsubsub29.mat');end
if ~subsubsub291_done
fprintf('\t\tEntering fsubsubsub291\n');
fsubsubsub291
fprintf('\t\tFinished with fsubsubsub291\n');
subsubsub291_done=true;
save('checkpoint_fsubsub29.mat');
end
if ~subsubsub292_done
fprintf('\t\tEntering fsubsubsub292\n');
fsubsubsub292% The break may occur in here
fprintf('\t\tFinished with fsubsubsub292\n')
subsubsub292_done=true;
save(checkpoint_fsubsub29.mat');
end
delete('checkpoint_fsubsub29.mat');
end
So in this structure if you restarted the program after it was killed it would resume back to the last saved checkpoint. So for example if the program died in subsubsub291, the program would skip fsub1 altogether, just loading the result. And then it would skip subsub21 all the way down to subsub29 where it would enter subsub29. Then it would skip subsubsub291 and enter 292 where it left off, having loaded all of the variables in that workspace and in previous workspaces. So if you backed out of 292 into 29 you would have the same workspace as if the code just ran. Note that this will also print a nice tree structure as it enters and exits functions to help debug execution order.
Reference:
https://wiki.hpcc.msu.edu/pages/viewpage.action?pageId=14781653
After a bit of googling, I found that using putvar (custom function from here: http://au.mathworks.com/matlabcentral/fileexchange/27106-putvar--uigetvar ) solved this.
My code is really too long to be posted here, even by little portions. So I will just ask for one or two things :
It appears to me that when modifying the 'Data' property of an uitable 'ht' :
set(ht, 'Data', something);
that the "cellSelectionCallback" routine is triggered (as the selection is very likely to have changed, indeed), but not immediatly after the dataset is modified.
Is this true ?
Is there any way to prevent such a behavoir ?
Thanks !
I have code using a uitable, e.g:
tbl = uitable('Parent', fh, 'CellSelectionCallback',{#cell_select_callback fh});
I did a quick experiment and when using set(tbl,'Data',my_data) the callback is triggered only if the set causes the selected cell(s) to change, and this happens immediately (as far as I can tell - I saw no appreciable delay).
To stop that happening you could just unset the CellSelectionCallback property, change the data, and then reset CellSelectionCallback.
I had the same issue. Was getting index out of bounds warnings. To get rid of those I used this in my CallSelectionCallback:
if ~isempty(eventdata.Indices)
// all the code
end
When the set command triggers the CallSelectionCallback the eventdata.Indices is empty.
A similar possibility to Sebastien's answer is to put this in your cellselectioncallback function:
function output = mycellselection(source,event)
if isempty(event.Indixes)
output = [];
return
end
% rest of your code for cell selection
end
If you don't have any output needed, you can just remove it. I just put it in there to remind you that you have to assign a value to any outputs.