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Tungky Subroto
Tungky Subroto
Last activity 2021 年 2 月 28 日

Hi all,
I hope everyone is doing well and keeping safe. I was wondering, are there any Cody challenges for Simulink these days?
I saw a post from 2015 (https://blogs.mathworks.com/simulink/2015/08/07/modeling-and-simulation-challenge-in-cody/) and it seems there was a Simulink or "Modeling and Simulation Challenge" problem group, but I couldn't find this group anymore. Perhaps I missing something?
Thank you beforehand.
Tungky
Is anyone else disappointed with uifigures? It seems apparent that these will eventually replace traditional figures, but there is still so much that doesn't quite work. I've tinkered with uifigures since their introduction in release 2016a, but even in 2020a I can't reliably export a uifigure to a graphics file. Sure it works sometimes, but not if a uipanel is present. The exportgraphics command is not as powerful as the print command, leaving some graphic formats (such as *.svg and *.eps) unsupported. How do you generate graphic files of a specific size? You can't even use subplots without overriding the default AutoResizeChildren setting!
Everything with uifigures seems to be slower and less stable than the figure variant. App Designer is much better than GUIDE, but that is not exactly high praise. I would rather generate "apps" programatically across several files instead of dealing with a single-file class definition containing 1000+ lines.
Where is this transition going? MATLAB graphics are moving away from Java in favor of JavaScript, and I'm not sure that we are at all ready for that.
David
David
Last activity 2021 年 2 月 23 日

MATLAB Answers will now properly handle the use of the '*@*' character when you want to get someone's attention. This behavior is commonly referred to as 'mentioning' or 'tagging' someone and is a feature found in most communication apps.

Why we are doing this

To help with communication and potentially speed up conversations. Also, it turns out many of you have been typing the @ character in Answers already, even though the MATLAB Answers site didn't behave in the expected way.

How it works

Once you type the @ character a popup will appear listing the community members already in the Q/A thread, as you keep typing the list will expand to include members not in the thread. A mentioned user will receive a notification when the question/answer/comment is posted. Each mention in the Q/A thread will have a new visual style and link to the user profile for that community member.

If you don't want to get 'mentioned' you can turn off the setting in your communication preferences located on your profile page .

We hope you will find this feature helpful and as always please reply with any feedback you may have.

David
David
Last activity 2021 年 3 月 12 日

We have created a new community for users of ThingSpeak. This new community is for students, researchers, and engineers looking to use MATLAB, Simulink, and ThingSpeak for Internet of Things applications. You can find the latest ThingSpeak news, tutorials to jump-start your next IoT project, and a forum to engage in a discussion on your latest cloud-based project. You can see answers to problems other users have solved and share how you solved a problem.

Christopher Stapels will be moderating the new ThingSpeak community .

We encourage you to visit the new community and share best practices, examples, and ask questions.

David
David
Last activity 2021 年 1 月 21 日

Ameer Hamza had a great 2020 and has been awarded the coveted MOST ACCEPTED answers badge for all his contributions in MATLAB Answers this past year. Ameer joins Walter Roberson and Image Analyst in receiving this award going all the way back to 2012!

There are 10 community members who have achieved the Top Downloads badge for their popular File Exchange submissions in 2020. Do you recognize any of these names? There's a good chance you've used one or more of their toolboxes or scripts in your work if you're a frequent visitor to File Exchange, if you're not you might want to check out what they've posted, it may save you a lot of time writing your own code.

--------------------- Top Downloads Badge Winners -----------------

Congratulations to all these winners and a giant THANK YOU for all they've done this past year to help everyone in the MATLAB Central community!

I see this solution on the Cody solutions list. Solution 1949216
I am puzzled as to how this could possibly be rated as correct (size 48)
(BTW - I am pretty sure I saw this, or similar, before.)
function ans = fileread(varargin)
' ';
a=1;
b=3;
a=1;
b=3;a=1;
b=3;a=1;
b=3;a=1;
b=3; end
  1. Use the new exportapp function to capture an image of your app|uifigure
  2. MATLAB's getframe now supports apps & uifigures
  3. Review: How to get the handle to an app figure

Use the new exportapp function to capture an image of your app|uifigure

Imagine these scenarios:

  • Your app contains several adjustable parameters that update an embedded plot and you'd like to remember the values of each app component so that you can recreate the plot with the same dataset
  • You're constructing a manual for your app and would like to include images of your app
  • You're app contains a process that automatically updates regularly and you'd like to store periodic snapshots of your app.

As of MATLABs R2020b release , we no longer must rely on 3rd party software to record an image of an app or uifigure.

exportapp(fig,filename) saves an image (JPEG | PNG | TIFF | PDF) of a uifigure ( fig) with the specified file name or full file path ( filename). MATLAB's documentation includes an example of how to add an [Export] button to an app that allows the user to select a path, filename, and extension for their exported image.

Here's another example that merely saves the image as a PDF to the app's main folder.

1. Add a button to the app and assign a ButtonPushed callback function to the button. This one also assigns an icon to the button in the form of an svg file.

2. Define the callback function to name the image after the app's name and include a datetime stamp. The image will be saved to the app's main folder.

% Button pushed function: SnapshotButton
function SnapshotButtonPushed(app, ~) 
    % create filename containing the app's figure name (spaces removed)
    % and a datetime stamp in format yymmdd_hhmmss
    filename = sprintf('%s_%s.pdf',regexprep(app.MyApp.Name,' +',''), datestr(now(),'yymmdd_HHMMSS'));
    % Get the app's path
    filepath = fileparts(which([mfilename,'.mlapp']));
    % Store snapshot
    exportapp(app.MyApp, fullfile(filepath,filename))
end

Matlab's getframe now supports apps & uifigures

getframe(h) captures images of axes or a uifigure as a structure containing the image data which defines a movie frame. This function has been around for a while but as of r2020b , it now supports uifigures. By capturing consecutive frames, you can create a movie that can be played back within a Matlab figure (using movie ) or as an AVI file (using VideoWriter ). This is useful when demonstrating the effects of changes to app components.

The general steps to recording a process within an app as a movie are,

1. Add a button or some other event to your app that can invoke the frame recording process.

2. Animation is typically controlled by a loop with n iterations. Preallocate the structure array that will store the outputs to getframe. The example below stores the outputs within the app so that they are available by other functions within the app. That will require you to define the variable as a property in the app.

% nFrames is the number of iterations that will be recorded.
% recordedFrames is defined as a private property within the app
app.recordedFrames(1:nFrames) = struct('cdata',[],'colormap',[]);

3. Call getframe from within the loop that controls the animation. If you're using VideoWriter to create an AVI file, you'll also do that here (not shown, but see an example in the documentation ).

% app.myAppUIFigure: the app's figure handle
% getframe() also accepts axis handles
for i = 1:nFrames
      ... % code that updates the app for the next frame
      app.recordedFrames(i) = getframe(app.myAppUIFigure);
  end

4. Now the frame data are stored in app.recordedFrames and can be accessed from anywhere within the app. To play them back as a movie,

movie(app.recordedFrames) 
% or 
movie(app.recordedFrames, n) % to play the movie n-times
movie(app.recordedFrames, n, fps) % to specify the number of frames per second

To demonstrate this, I adapted a copy of Matlab's built-in PulseGenerator.mlapp by adding

  • a record button
  • a record status lamp with frame counter
  • a playback button
  • a function that animates the effects of the Edge Knob

Recording process (The GIF is a lot faster than realtime and only shows part of the recording) (Open the image in a new window or see the attached Live Script for a clearer image).

Playback process (Open the image in a new window or see the attached Live Script for a clearer image.)

Review: How to get the handle to an app figure

To use either of these functions outside of app designer, you'll need to access the App's figure handle. By default, the HandleVisibility property of uifigures is set to off preventing the use of gcf to retrieve the figure handle. Here are 4 ways to access the app's figure handle from outside of the app.

1. Store the app's handle when opening the app.

app = myApp;
% Get the figure handle
figureHandle = app.myAppUIFigure;

2. Search for the figure handle using the app's name, tag, or any other unique property value

allfigs = findall(0, 'Type', 'figure'); % handle to all existing figures
figureHandle = findall(allfigs, 'Name', 'MyApp', 'Tag', 'MyUniqueTagName');

3. Change the HandleVisibility property to on or callback so that the figure handle is accessible by gcf anywhere or from within callback functions. This can be changed programmatically or from within the app designer component browser. Note, this is not recommended since any function that uses gcf such as axes(), clf(), etc can now access your app!.

4. If the app's figure handle is needed within a callback function external to the app, you could pass the app's figure handle in as an input variable or you could use gcbf() even if the HandleVisibility is off.

See a complete list of changes to the PulseGenerator app in the attached Live Script file to recreate the app.

File Exchange now offers the ability to download/restore previous versions of community contributed files. It's often a good practice to always update your software to the latest version, however there are times when this isn't always helpful. Sometimes a software update can break or alter something you've been relying on, in these cases you'll want to stick with the version that's working for you. This is why we've added the ability to download previous versions in File Exchange.

Using Version History

Navigate to any community member file and then click the View Version History link that appears above the Download button. This will show you a list of the previous versions contributed by the submission author. Each version will have a corresponding download button, date, version number, and a description of the changes made for that update.

Let us know what you think about this new feature by replying below.

Prior to r2020b the height (number of rows) and width (number of columns) of an array or table can be determined by the size function,

array = rand(102, 16);
% Method 1
[dimensions] = size(array);
h = dimensions(1);
w = dimensions(2);
% Method 2
[h, w] = size(array); %#ok<*ASGLU>
% or
[h, ~] = size(array);
[~, w] = size(array);
% Method 3
h = size(array,1);
w = size(array,2);

In r2013b, the height(T) and width(T) functions were introduced to return the size of single dimensions for tables and timetables.

Starting in r2020b, height() and width() can be applied to arrays as an alternative to the size() function.

Continuing from the section above,

h = height(array)
% h =  102
w = width(array)
% w =  16

height() and width() can also be applied to multidimensional arrays including cell and structure arrays

mdarray = rand(4,3,20);
h = height(mdarray)
% h =  4
w = width(mdarray)
% w =  3

The expanded support of the height() and width() functions means,

  1. when reading code, you can no longer assume the variable T in height(T) or width(T) refers to a table or timetable
  2. greater flexibility in expressions such as the these, below
% C is a 1x4 cell array containing 4 matrices with different dimensions
rng('default')
C = {rand(5,2), rand(2,3), rand(3,4), rand(1,1)};
celldisp(C)
% C{1} =
%       0.81472      0.09754
%       0.90579       0.2785
%       0.12699      0.54688
%       0.91338      0.95751
%       0.63236      0.96489
% C{2} =
%       0.15761      0.95717      0.80028
%       0.97059      0.48538      0.14189
% C{3} =
%       0.42176      0.95949      0.84913      0.75774
%       0.91574      0.65574      0.93399      0.74313
%       0.79221     0.035712      0.67874      0.39223
% C{4} =
%       0.65548

What's the max number of rows in C?

maxRows1 = max(cellfun(@height,C))         % using height()
% maxRows1 =  5;
maxRows2 = max(cellfun(@(x)size(x,1),C))   % using size()
% maxRows2 =  5; 

What's the total number of columns in C?

totCols1 = sum(cellfun(@width,C))          % using width()
%totCols1 =  10
totCols2 = sum(cellfun(@(x)size(x,2),C))   % using size(x,2)
% totCols2 =  10

Attached is a live script containing the content of this post.

'
The Matlab r2020b release introduces the new horizontal ('_') and vertical (' | ') line marker symbols that are centered around the coordinate similarly to the plus marker ('+').
plot(x,y,'_')
plot(x,y,'|')
See the attached Live Script to reproduce all plots in this post.
'
Use case example 1: Days in August 2020 that COVID-19 cases (vertical ticks) and number of tests (horizontal ticks) increased from the previous day in countries with populations greater than 100M (4 countries eliminated for incomplete data).
'
Use case example 2: (An alternative to stacked bar plots) Number of power outages in 2005 across regions of the USA, broken down by calendar quarters.

Please join Loren Shure for her live sessions on the MATLAB YouTube channel starting October 1st and continuing through November 19th. You know Loren from her popular blog Loren on the Art of MATLAB.

Chen Lin
Chen Lin
Last activity 2020 年 11 月 24 日

Solve coding problems. Improve MATLAB skills. Have fun. See details and register .

Add a subtitle

Multi-lined titles have been supported for a long time but starting in r2020b, you can add a subtitle with its own independent properties to a plot in two easy ways.

  1. Use the new subtitle function: s=subtitle('mySubtitle')
  2. Use the new second argument to the title function: [t,s]=title('myTitle','mySubtitle')
figure()
tiledlayout(2,2)
% Method 1
ax(1) = nexttile;
th(1) = title('Pupil size'); 
sh(1) = subtitle('Happy faces');
ax(2) = nexttile;
th(2) = title('Pupil size'); 
sh(2) = subtitle('Sad faces');
% Method 2
ax(3) = nexttile;
[th(3), sh(3)] = title('Fixation duration', 'Happy faces'); 
ax(4) = nexttile;
[th(4), sh(4)] = title('Fixation duration', 'Sad faces'); 
set(ax, 'xticklabel', [], 'yticklabel', [],'xlim',[0,1],'ylim',[0,1])
% Set all title colors to orange and subtitles colors to purple.
set(th, 'Color', [0.84314, 0.53333, 0.1451])
set(sh, 'Color', [0, 0.27843, 0.56078])

Control title/Label alignment

Title and axis label positions can be changed via their Position, VerticalAlignment and HorizontalAlignment properties but this is usually clumsy and leads to other problems when trying to align the title or labels with an axis edge. For example, when the position units are set to 'data' and the axis limits change, the corresponding axis label will change position relative to the axis edges. If units are normalized and the axis position or size changes, the corresponding label will no longer maintain its relative position to the axis, and that's assuming the normalized position was computed correctly in the first place.

Starting in r2020b, title and axis label alignment can be set to center|left|right, relative to the axis edges.

  • TitleHorizontalAlignment is a property of the axis: h.TitleHorizontalAlignment='left';
  • LabelHorizontalAlignment is a property of the ruler object that defines the x | y | z axis: h.XAxis.LabelHorizontalAlignment='left';
% Create data
x = randi(50,1,100)'; 
y = x.*[.2, -.2] + (rand(numel(x),2)-.5)*10; 
gray = [.65 .65 .65];
% Plot comparison between columns of y
figure()
tiledlayout(2,2,'TileSpacing','none')
ax(1) = nexttile(1);
plot(x, y(:,1), 'o', 'color', gray)
lsline
ylabel('Y1 (units)')
title('Regression','Y1 & Y2 separately')
ax(2) = nexttile(3);
plot(x, y(:,2), 'd', 'color', gray)
lsline
xlabel('X Label (units)')
ylabel('Y2 (units)')
grid(ax, 'on')
linkaxes(ax, 'x')
%  Move title and labels leftward
set(ax, 'TitleHorizontalAlignment', 'left')
set([ax.XAxis], 'LabelHorizontalAlignment', 'left')
set([ax.YAxis], 'LabelHorizontalAlignment', 'left')
% Combine the two comparisons into plot and flip the second 
% y-axis so trend are in the same direction
ax(3) = nexttile([2,1]);
yyaxis('left')
plot(x, y(:,1), 'o')
ylim([-6,16])
lsline
xlabel('X Label (units)')
ylabel('Y1 (units) \rightarrow')
yyaxis('right')
plot(x, y(:,2), 'd')
ylim([-16,6])
lsline
ylabel('\leftarrow Y2 (units)')
title('Direct comparison','(Y2 axis flipped)')
set(ax(3),  'YDir','Reverse')
% Align the ylabels with the minimum axis limit to emphasize the
% directions of each axis. Keep the title and xlabel centered
ax(3).YAxis(1).LabelHorizontalAlignment = 'left';
ax(3).YAxis(2).LabelHorizontalAlignment = 'right';
ax(3).TitleHorizontalAlignment = 'Center';       % not needed; default value.
ax(3).XAxis.LabelHorizontalAlignment = 'Center'; % not needed; default value.
It's pretty odd how a solution that uses more characters than usual can be the "leading solution" of a Cody problem and have the least size. Compare these two codes that find the sum of integers from 1 to 2^x, which one uses fewer characters, thus should be the better solution?
function y = sum_int(x)
regexp '' '(?@y=sum(1:2^x);)'
end
function ans = sum_int(x)
sum(1:2^x)
end
Is anyone using the MATLAB Discord channel?
Meta threads have a tendency to grow large. This has happened several times before (the wishlist threads #1 #2 #3 #4 #5, and 'What frustrates you about MATLAB?' #1 and #2).
No wonder that a thread from early 2011 has also kept growing. After just under a decade there are (at time of writing) 119 answers, making the page slow to load and navigate (especially on mobile). So after a friendly nudge; here is a new thread for the things that are missing from Matlab.
Same question: are there things you think should be possible in Matlab, but aren't? What things are possible with software packages similar to Matlab that Matlab would benefit from? (note that you can also submit an enhancement request through support, although I suspect they will be monitoring activity on this thread as well)
What should you post where?
Wishlist threads (#1 #2 #3 #4 #5): bugs and feature requests for Matlab Answers
Frustation threads (#1 #2): frustations about usage and capabilities of Matlab itself
Missing feature threads (#1 #2): features that you whish Matlab would have had
Next Gen threads (#1): features that would break compatibility with previous versions, but would be nice to have
@anyone posting a new thread when the last one gets too large (about 50 answers seems a reasonable limit per thread), please update this list in all last threads. (if you don't have editing privileges, just post a comment asking someone to do the edit)
Rik
Rik
Last activity 2024 年 9 月 17 日

Similar to what has happened with the wishlist threads (#1 #2 #3 #4 #5), the "what frustrates you about MATLAB" thread has become very large. This makes navigation difficult and increases page load times.
So here is the follow-up page.
What should you post where?
Wishlist threads (#1 #2 #3 #4 #5): bugs and feature requests for Matlab Answers
Frustation threads (#1 #2): frustations about usage and capabilities of Matlab itself
Missing feature threads (#1 #2): features that you whish Matlab would have had
Next Gen threads (#1): features that would break compatibility with previous versions, but would be nice to have
@anyone posting a new thread when the last one gets too large (about 50 answers seems a reasonable limit per thread), please update this list in all last threads. (if you don't have editing privileges, just post a comment asking someone to do the edit)

Starting in r2020a , you can change the mouse pointer symbol in apps and uifigures.

The Pointer property of a figure defines the cursor’s default pointer symbol within the figure. You can also create your own pointer symbols (see part 3, below).

Part 1. How to define a default pointer symbol for a uifigure or app

For figures or uifigures, set the pointer property when you define the figure or change the pointer property using the figure handle.

% Set pointer when creating the figure
uifig = uifigure('Pointer', 'crosshair');
% Change pointer after creating the figure
uifig.Pointer = 'crosshair';

For apps made in AppDesigner, you can either set the pointer from the Design View or you can set the pointer property of the app’s UIFigure from the startup function using the second syntax shown above.

Part 2. How to change the pointer symbol dynamically

The pointer can be changed by setting specific conditions that trigger a change in the pointer symbol.

For example, the pointer can be temporarily changed to a busy-symbol when a button is pressed. This ButtonPushed callback function changes the pointer for 1 second.

function WaitasecondButtonPushed(app, event)
   % Change pointer for 1 second.
   set(app.UIFigure, 'Pointer','watch')
   pause(1)
   % Change back to default.
   set(app.UIFigure, 'Pointer','arrow')
   app.WaitasecondButton.Value = false;
end

The pointer can be changed every time it enters or leaves a uiaxes or any plotted object within the uiaxes. This is controlled by a set of pointer management functions that can be set in the app’s startup function.

iptSetPointerBehavior(obj,pointerBehavior) allows you to define what happens when the pointer enters, leaves, or moves within an object. Currently, only axes and axes objects seem to be supported for UIFigures.

iptPointerManager(hFigure,'enable') enables the figure’s pointer manager and updates it to recognize the newly added pointer behaviors.

The snippet below can be placed in the app’s startup function to change the pointer to crosshairs when the pointer enters the outerposition of a uiaxes and then change it back to the default arrow when it leaves the uiaxes.

% Define pointer behavior when pointer enter axes
pm.enterFcn = @(~,~) set(app.UIFigure, 'Pointer', 'crosshair');
pm.exitFcn  = @(~,~) set(app.UIFigure, 'Pointer', 'arrow');
pm.traverseFcn = [];
iptSetPointerBehavior(app.UIAxes, pm)
% Enable pointer manager for app
iptPointerManager(app.UIFigure,'enable'); 

Any function can be triggered when entering/exiting an axes object which makes the pointer management tools quite powerful. This snippet below defines a custom function cursorPositionFeedback() that responds to the pointer entering/exiting a patch object plotted within the uiaxes. When the pointer enters the patch, the patch color is changed to red, the pointer is changed to double arrows, and text appears in the app’s text area. When the pointer exits, the patch color changes back to blue, the pointer changes back to crosshairs, and the text area is cleared.

% Plot patch on uiaxes
hold(app.UIAxes, 'on')
region1 = patch(app.UIAxes,[1.5 3.5 3.5 1.5],[0 0 5 5],'b','FaceAlpha',0.07,...
    'LineWidth',2,'LineStyle','--','tag','region1');
% Define pointer behavior for patch
pm.enterFcn = @(~,~) cursorPositionFeedback(app, region1, 'in');
pm.exitFcn  = @(~,~) cursorPositionFeedback(app, region1, 'out');
pm.traverseFcn = [];
iptSetPointerBehavior(region1, pm)
% Enable pointer manager for app
iptPointerManager(app.UIFigure,'enable');
function cursorPositionFeedback(app, hobj, inout)
% When inout is 'in', change hobj facecolor to red and update textbox.
% When inout is 'out' change hobj facecolor to blue, and clear textbox.
% Check tag property of hobj to identify the object.
switch lower(inout)
    case 'in'
        facecolor = 'r';
        txt = 'Inside region 1';
        pointer = 'fleur';
    case 'out'
        facecolor = 'b';
        txt = '';
        pointer = 'crosshair';
end
hobj.FaceColor = facecolor;
app.TextArea.Value = txt;
set(app.UIFigure, 'Pointer', pointer)
end  

The app showing the demo below is attached.

Part 3. Create your own custom pointer symbol

  1. Set the figure’s pointer property to ‘custom’.
  2. Set the figure’s PointerShapeCData property to the custom pointer matrix. A custom pointer is defined by a 16x16 or 32x32 matrix where NaN values are transparent, 1=black, and 2=white.
  3. Set the figure’s PointerShapeHotSpot to [m,n] where m and n are the coordinates that define the tip or "hotspot" of the matrix.

This demo uses the attached mat file to create a black hand pointer symbol.

iconData = load('blackHandPointer.mat');
uifig = uifigure(); 
uifig.Pointer = 'custom'; 
uifig.PointerShapeCData = iconData.blackHandIcon; 
uifig.PointerShapeHotSpot = iconData.hotspot;

Also see Jiro's pointereditor() function on the file exchange which allows you to draw your own pointer.

We are excited to announce that File Exchange now awards reputation points to the authors and you can view the points and rankings by week, month, year or all-time on the new leaderboard .
Reputation point is commonly used in many online communities to build trust and show appreciation to contributors. File Exchange rewards reputation points to authors who submit files, but it's definitely not easy to earn! You earn points when your files are downloaded or rated by other community members. Therefore, you should be very proud of yourself no matter you have 10 points or 10,000 points. It's the recognition from the community. See table below for detailed rules:
Now that we have reputation points on File Exchange, we introduced the short-term leaderboard to better view the points and rankings. You can filter by 7-day, 30-day, 365-day, and all-time, which helps you understand who is more active recently or who is a long-time contributor.
We hope the reputation and new leaderboard will contribute to the growth and success of File Exchange community. Your feedback is extremely valuable to us. Simply reply to this article if you have any questions, comments, or suggestions.
Chen Lin
Chen Lin
Last activity 2020 年 5 月 11 日

Today, I'm spotlighting Rik, our newest and the 31st MVP in MATLAB Answers. Two weeks ago, we just celebrated Ameer Hamza for reaching the MVP milestone. Today, we are thrilled that we have another new MVP!

Since his first answer in Feb 2017, Rik has been contributing high-quality answers every quarter!

Besides those high-quality answers, Rik so far has submitted 21 files to File Exchange, one of which was chosen by MathWorks as the 'Pick of the Week'. Check the shining badge below.

Congratulations Rik! Thank you for your hard work and outstanding contributions.

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