Results for
The "Issues" with Constant Properties
MATLABs Constant properties can be rather difficult to deal with at times. For those unfamiliar there are two distinct behaviors when accessing constant properties of a class. If a "static" pattern is used ClassName.PropName the the value, as it was assigned to the property is returned; that is to say that you will have a nargout of 1. But, rather frustratingly, if an instance of the class is used when accessing the constant property, such as ArrayOfClassName.PropName then your nargout will be equivalent to the number of elements in the array; this means that functionally the constant property accessing scheme is identical to that of the element wise properties you find on "instance" properties.
Motivation for Correcting Constant Property Behavior
This can be frustraing since constant properties are conceptually designed to tie data to a class. You could see this design pattern being useful where a super class were to define an abstract constant property, that would drive the behavior of subclasses; the subclasses define the value of the property and the super class uses it. I would like to use this design to develop a custom display "MatrixDisplay" focused mixin (like the internal matlab.mixin.internal.MatrixDisplay). The idea is that missing element labels, invalid handle element labels, and other semantic values can be configured by the subclasses, conveniently just by setting the constant properties; these properties will be used by the super class to substitute the display strings of appropriate elements. Most of the processing will happen within the super class as to enable simple, low-investment, opt-in display options for array style classes.
The issue is that you can not rely on constant property access to return the appropriate value when the instance you've been passed is empty. This also happens with excessive outputs when the instance is non-scalar, but those extra values from the CSL are just ignored, while Id imagine there is an effect on performance from generating the excess outputs (assuming theres no internal optimization for the unused outputs), this case still functions appropriately. As I enjoying exploring MATLAB, I found an internal indexing mixing class in the past that provides far greater control of do indexing; I've done a good deal of neat things with it, though at the cost of great overhead when getting implementing cool "proof of concept/showcase" examples. Today I used it to quickly implement a mix in that "fixes" constant properties such that they always return as though they were called statically from the class name, as opposed to an instance.
A Simplistic Solution
To do this I just intercepted the property indexing, checked if it was constant, and used the DefaultValue property of the metadata to return the value. This works nicely since we are required to attempt to initialize a "dummy" scalar array, or generate a function handle; both of those would likely be slower, and in the former case, may not be possible depending on the subclass implementation. It is worth noting that this method of querying the value from metadata is safe because constant properties are immutable and thus must be established as the class is loaded. Below is the small utility class I have implemented to get predictable constant variable access into classes that benefit from it. Lastly it is worth noting that I've not torture testing the rerouting of the indexing we aren't intercepting, in my limited play its behaved as expected but it may be worth looking over if you end up playing around with this and notice abnormal property assignment or reading from non-constant properties.
Sample Class Implementation
classdef(Abstract, HandleCompatible) ConstantProperty < matlab.mixin.internal.indexing.RedefinesDotProperties
%ConstantProperty Returns instance indexed constant properties as though they were statically indexed.
% This class overloads property access to check if the indexed property is constant and return it properly.
%% Property membership utility methods
methods(Access=private)
function [isConst, isProp] = isConstantProp(obj, prop, options)
%isConstantProp Determine if the input property names are constant properties of the input
arguments
obj mixin.ConstantProperty;
prop string;
options.Flatten (1, 1) logical = false;
end
% Store the cache to avoid rechecking string membership and parsing metadata
persistent class_cache
% Initialize cache for all subclasses to maintain their own caches
if(isempty(class_cache))
class_cache = configureDictionary("string", "dictionary");
end
% Gather the current class being analyzed
classname = string(class(obj));
% Check if the current class has a cache, if not make one
if(~isKey(class_cache, classname))
class_cache(classname) = configureDictionary("string", "struct");
end
% Alias the current classes cache
prop_cache = class_cache(classname);
% Check which inputs are already cached
isCached = isKey(prop_cache, prop);
% Add any values that have yet to be cached to the cache
if(any(~isCached, "all"))
% Flatten cache additions
props = row(prop(~isCached));
% Gather the meta-property data of the input object and determine if inputs are listed properties
mc_props = metaclass(obj).PropertyList;
% Determine which properties are keys
[isConst, idx] = ismember(props, string({mc_props.Name}));
idx = idx(isConst);
% Check which of the inputs are constant properties
isConst = repmat(isConst, 2, 1);
isConst(1, isConst(1, :)) = [mc_props(idx).Constant];
% Parse the results into structs for caching
cache_values = cell2struct(num2cell(isConst), ["isConst"; "isProp"]);
prop_cache(props) = row(cache_values);
% Re-sync the cache
class_cache(classname) = prop_cache;
end
% Extract results from the cache
values = prop_cache(prop);
if(options.Flatten)
% Split and reshape output data
sz = size(prop);
isConst = reshape(values.isConst, sz);
isProp = reshape(values.isProp, sz);
else
isConst = struct2cell(values);
end
end
function [isConst, isProp] = isConstantIdxOp(obj, idxOp)
%isConstantIdxOp Determines if the idxOp is referencing a constant property.
arguments
obj mixin.ConstantProperty;
idxOp (1, :) matlab.indexing.IndexingOperation;
end
import matlab.indexing.IndexingOperationType;
if(idxOp(1).Type == IndexingOperationType.Dot)
[isConst, isProp] = isConstantProp(obj, idxOp(1).Name);
else
[isConst, isProp] = deal(false);
end
end
function A = getConstantProperty(obj, idxOp)
%getConstantProperty Returns the value of a constant property using a static reference pattern.
arguments
obj mixin.ConstantProperty;
idxOp (1, :) matlab.indexing.IndexingOperation;
end
A = findobj(metaclass(obj).PropertyList, "Name", idxOp(1).Name).DefaultValue;
end
end
%% Dot indexing methods
methods(Access = protected)
function A = dotReference(obj, idxOp)
arguments(Input)
obj mixin.ConstantProperty;
idxOp (1, :) matlab.indexing.IndexingOperation;
end
arguments(Output, Repeating)
A
end
% Force at least one output
N = max(1, nargout);
% Check if the indexing operation is a property, and if that property is constant
[isConst, isProp] = isConstantIdxOp(obj, idxOp);
if(~isProp)
% Error on invalid properties
throw(MException( ...
"JB:mixin:ConstantProperty:UnrecognizedProperty", ...
"Unrecognized property '%s'.", ...
idxOp(1).Name ...
));
elseif(isConst)
% Handle forwarding indexing operations
if(isscalar(idxOp))
% Direct assignment
[A{1:N}] = getConstantProperty(obj, idxOp);
else
% First extract constant property then forward indexing operations
tmp = getConstantProperty(obj, idxOp);
[A{1:N}] = tmp.(idxOp(2:end));
end
else
% Handle forwarding indexing operations
if(isscalar(idxOp))
% Unfortunately we can't just recall obj.(idxOp) to use default/built-in so we manually extract
[A{1:N}] = obj.(idxOp.Name);
else
% Otherwise let built-in handling proceed
tmp = obj.(idxOp(1).Name);
[A{1:N}] = tmp.(idxOp(2:end));
end
end
end
function obj = dotAssign(obj, idxOp, values)
arguments(Input)
obj mixin.ConstantProperty;
idxOp (1, :) matlab.indexing.IndexingOperation;
end
arguments(Input, Repeating)
values
end
% Handle assignment based on presence of forward indexing
if(isscalar(idxOp))
% Simple broadcasted assignment
[obj.(idxOp.Name)] = deal(values{:});
else
% Initialize the intermediate values and expand the values for assignment
tmp = {obj.(idxOp(1).Name)};
[tmp.(idxOp(2:end))] = deal(values{:});
% Reassign the modified data to the output object
[obj.(idxOp(1).Name)] = deal(tmp{:});
end
end
function n = dotListLength(obj, idxOp, idxCnt)
arguments(Input)
obj mixin.ConstantProperty;
idxOp (1, :) matlab.indexing.IndexingOperation;
idxCnt (1, :) matlab.indexing.IndexingContext;
end
if(isConstantIdxOp(obj, idxOp))
if(isscalar(idxOp))
% Constant properties will also be 1
n = 1;
else
% Checking forwarded indexing operations on the scalar constant property
n = listLength(obj.(idxOp(1).Name), idxOp(2:end), idxCnt);
end
else
% Check the indexing operation normally
% n = listLength(obj, idxOp, idxCnt);
n = numel(obj);
end
end
end
end
k-Wave is a MATLAB community toolbox with a track record that includes over 2,500 citations on Google Scholar and over 7,500 downloads on File Exchange. It is built for the "time-domain simulation of acoustic wave fields" and was recently highlighted as a Pick of the Week.
In December, release v1.4.1 was published on GitHub including two new features led by the project's core contributors with domain experts in this field. This first release in several years also included quality and maintainability enhancements supported by a new code contributor, GitHub user stellaprins, who is a Research Software Engineer at University College London. Her contributions in 2025 spanned several software engineering aspects, including the addition of continuous integration (CI), fixing several bugs, and updating date/time handling to use datetime. The MATLAB Community Toolbox Program sponsored these contributions, and welcomes to see them now integrated into a release for k-Wave users.
I'd like to share some work from Controls Educator and long term collabortor @Dr James E. Pickering from Harper Adams University. He is currently developing a teaching architecture for control engineering (ACE-CORE) and is looking for feedback from the engineering community.
ACE-CORE is delivered through ACE-Box, a modular hardware platform (Base + Sense, Actuate). More on the hardware here: What is the ACE-Box?
The Structure
(1) Comprehend
Learners build conceptual understanding of control systems by mapping block diagrams directly to physical components and signals. The emphasis is on:
- Feedback architecture
- Sensing and actuation
- Closed-loop behaviour in practical terms
(2) Operate
Using ACE-Box (initially Base + Sense), learners run real closed-loop systems. The learners measure, actuate, and observe real phenomena such as: Noise, Delay, Saturation
Engineering requirements (settling time, overshoot, steady-state error, etc.) are introduced explicitly at this stage.
After completing core activities (e.g., low-pass filter implementation or PID tuning), the pathway branches (see the attached diagram)
(3a) Refine (Option 1) Students improve performance through structured tuning:
- PID gains
- Filter coefficients
- Performance trade-offs
The focus is optimisation against defined engineering requirements.
(3b) Refine → Engineer (Option 2)
Modelling and analytical design become more explicit at this stage, including:
- Mathematical modelling
- Transfer functions
- System identification
- Stability analysis
- Analytical controller design
Why the Branching?
The structure reflects two realities:
- Engineers who operate and refine existing control systems
- Engineers who design control systems through mathematical modelling
Your perspective would be very valuable:
- Does this progression reflect industry reality?
- Is the branching structure meaningful?
- What blind spots do you see?
Constructive critique is very welcome. Thank you!
Hello All,
This is my first post here so I hope its in the right place,
I have built myself a GW consisting of a RAK2245 concentrator and a Raspberry Pi, Also an Arduino end device from this link https://tum-gis-sensor-nodes.readthedocs.io/en/latest/dragino_lora_arduino_shield/README.html
Both projects work fine and connect to TTN whereby packets of data from the end device can be seen in the TTN console.
I now want to create a Webhook in TTN for Thingspeak which would hopefull allow me to see Temperature , Humidity etc in graphical form.
My question, does thingspeak support homebuilt devices or is it focused on comercially built devices ?
I have spent many hours trying to find data hosting site that is comepletely free for a few devices and not to complicated to setup as some seem to be a nightmare. Thanks for any support .
How can I found my license I'd and password, so please provide me my id
Over the past few days I noticed a minor change on the MATLAB File Exchange:
For a FEX repository, if you click the 'Files' tab you now get a file-tree–style online manager layout with an 'Open in new tab' hyperlink near the top-left. This is very useful:
If you want to share that specific page externally (e.g., on GitHub), you can simply copy that hyperlink. For .mlx files it provides a perfect preview. I'd love to hear your thoughts.
EXAMPLE:
🤗🤗🤗
I wanted to share something I've been thinking about to get your reactions. We all know that most MATLAB users are engineers and scientists, using MATLAB to do engineering and science. Of course, some users are professional software developers who build professional software with MATLAB - either MATLAB-based tools for engineers and scientists, or production software with MATLAB Coder, MATLAB Compiler, or MATLAB Web App Server.
I've spent years puzzling about the very large grey area in between - engineers and scientists who build useful-enough stuff in MATLAB that they want their code to work tomorrow, on somebody else's machine, or maybe for a large number of users. My colleagues and I have taken to calling them "Reluctant Developers". I say "them", but I am 1,000% a reluctant developer.
I first hit this problem while working on my Mech Eng Ph.D. in the late 90s. I built some elaborate MATLAB-based tools to run experiments and analysis in our lab. Several of us relied on them day in and day out. I don't think I was out in the real world for more than a month before my advisor pinged me because my software stopped working. And so began a career of building amazing, useful, and wildly unreliable tools for other MATLAB users.
About a decade ago I noticed that people kept trying to nudge me along - "you should really write tests", "why aren't you using source control". I ignored them. These are things software developers do, and I'm an engineer.
I think it finally clicked for me when I listened to a talk at a MATLAB Expo around 2017. An aerospace engineer gave a talk on how his team had adopted git-based workflows for developing flight control algorithms. An attendee asked "how do you have time to do engineering with all this extra time spent using software development tools like git"? The response was something to the effect of "oh, we actually have more time to do engineering. We've eliminated all of the waste from our unamanaged processes, like multiple people making similar updates or losing track of the best version of an algorithm." I still didn't adopt better practices, but at least I started to get a sense of why I might.
Fast-forward to today. I know lots of users who've picked up software dev tools like they are no big deal, but I know lots more who are still holding onto their ad-hoc workflows as long as they can. I'm on a bit of a campaign to try to change this. I'd like to help MATLAB users recognize when they have problems that are best solved by borrowing tools from our software developer friends, and then give a gentle onramp to using these tools with MATLAB.
I recently published this guide as a start:
Waddya think? Does the idea of Reluctant Developer resonate with you? If you take some time to read the guide, I'd love comments here or give suggestions by creating Issues on the guide on GitHub (there I go, sneaking in some software dev stuff ...)
I recently created a short 5-minute video covering 10 tips for students learning MATLAB. I hope this helps!
DocMaker allows you to create MATLAB toolbox documentation from Markdown documents and MATLAB scripts.
The MathWorks Consulting group have been using it for a while now, and so David Sampson, the director of Application Engineering, felt that it was time to share it with the MATLAB and Simulink community.
David listed its features as:
➡️ write documentation in Markdown not HTML
🏃 run MATLAB code and insert textual and graphical output
📜 no more hand writing XML index files
🕸️ generate documentation for any release from R2021a onwards
💻 view and edit documentation in MATLAB, VS Code, GitHub, GitLab, ...
🎉 automate toolbox documentation generation using MATLAB build tool
📃 fully documented using itself
😎 supports light, dark, and responsive modes
🐣 cute logo
I got an email message that says all the files I've uploaded to the File Exchange will be given unique names. Are these new names being applied to my files automatically? If so, do I need to download them to get versions with the new name so that if I update them they'll have the new name instead of the name I'm using now?
A coworker shared with me a hilarious Instagram post today. A brave bro posted a short video showing his MATLAB code… casually throwing 49,000 errors!
Surprisingly, the video went virial and recieved 250,000+ likes and 800+ comments. You really never know what the Instagram algorithm is thinking, but apparently “my code is absolutely cooked” is a universal developer experience 😂
Last note: Can someone please help this Bro fix his code?
Is it possible to display a variable value within the ThingSpeak plot area?
https://www.mathworks.com/matlabcentral/answers/2182045-why-can-t-i-renew-or-purchase-add-ons-for-m…
"As of January 1, 2026, Perpetual Student and Home offerings have been sunset and replaced with new Annual Subscription Student and Home offerings."
So, Perpetual licenses for Student and Home versions are no more. Also, the ability for Student and Home to license just MATLAB by itself has been removed.
The new offering for Students is $US119 per year with no possibility of renewing through a Software Maintenance Service type offering. That $US119 covers the Student Suite of MATLAB and Simulink and 11 other toolboxes. Before, the perpetual license was $US99... and was a perpetual license, so if (for example) you bought it in second year you could use it in third and fourth year for no additional cost. $US99 once, or $US99 + $US35*2 = $US169 (if you took SMS for 2 years) has now been replaced by $US119 * 3 = $US357 (assuming 3 years use.)
The new offering for Home is $US165 per year for the Suite (MATLAB + 12 common toolboxes.) This is a less expensive than the previous $US150 + $US49 per toolbox if you had a use for those toolboxes . Except the previous price was a perpetual license. It seems to me to be more likely that Home users would have a use for the license for extended periods, compared to the Student license (Student licenses were perpetual licenses but were only valid while you were enrolled in degree granting instituations.)
Unfortunately, I do not presently recall the (former) price for SMS for the Home license. It might be the case that by the time you added up SMS for base MATLAB and the 12 toolboxes, that you were pretty much approaching $US165 per year anyhow... if you needed those toolboxes and were willing to pay for SMS.
But any way you look at it, the price for the Student version has effectively gone way up. I think this is a bad move, that will discourage students from purchasing MATLAB in any given year, unless they need it for courses. No (well, not much) more students buying MATLAB with the intent to explore it, knowing that it would still be available to them when it came time for their courses.
You may have come across code that looks like that in some languages:
stubFor(get(urlPathEqualTo("/quotes"))
.withHeader("Accept", equalTo("application/json"))
.withQueryParam("s", equalTo(monitoredStock))
.willReturn(aResponse())
.withStatus(200)
.withHeader("Content-Type", "application/json")
.withBody("{\\"symbol\\": \\"XYZ\\", \\"bid\\": 20.2, " + "\\"ask\\": 20.6}")))
That’s Java. Even if you can’t fully decipher it, you can get a rough idea of what it is supposed to do, build a rather complex API query.
Or you may be familiar with the following similar and frequent syntax in Python:
import seaborn as sns
sns.load_dataset('tips').sample(10, random_state=42).groupby('day').mean()
Here’s is how it works: multiple method calls are linked together in a single statement, spanning over one or several lines, usually because each method returns the same object or another object that supports further calls.
That technique is called method chaining and is popular in Object-Oriented Programming.
A few years ago, I looked for a way to write code like that in MATLAB too. And the answer is that it can be done in MATLAB as well, whevener you write your own class!
Implementing a method that can be chained is simply a matter of writing a method that returns the object itself.
In this article, I would like to show how to do it and what we can gain from such a syntax.
Example
A few years ago, I first sought how to implement that technique for a simulation launcher that had lots of parameters (far too many):
lauchSimulation(2014:2020, true, 'template', 'TmplProd', 'Priority', '+1', 'Memory', '+6000')
As you can see, that function takes 2 required inputs, and 3 named parameters (whose names aren’t even consistent, with ‘Priority’ and ‘Memory’ starting with an uppercase letter when ‘template’ doesn’t).
(The original function had many more parameters that I omit for the sake of brevity. You may also know of such functions in your own code that take a dozen parameters which you can remember the exact order.)
I thought it would be nice to replace that with:
SimulationLauncher() ...
.onYears(2014:2020) ...
.onDistributedCluster() ... % = equivalent of the previous "true"
.withTemplate('TmplProd') ...
.withPriority('+1') ...
.withReservedMemory('+6000') ...
.launch();
The first 6 lines create an object of class SimulationLauncher, calls several methods on that object to set the parameters, and lastly the method launch() is called, when all desired parameters have been set.
To make it cleared, the syntax previously shown could also be rewritten as:
launcher = SimulationLauncher();
launcher = launcher.onYears(2014:2020);
launcher = launcher.onDistributedCluster();
launcher = launcher.withTemplate('TmplProd');
launcher = launcher.withPriority('+1');
launcher = launcher.withReservedMemory('+6000');
launcher.launch();
Before we dive into how to implement that code, let’s examine the advantages and drawbacks of that syntax.
Benefits and drawbacks
Because I have extended the chained methods over several lines, it makes it easier to comment out or uncomment any one desired option, should the need arise. Furthermore, we need not bother any more with the order in which we set the parameters, whereas the usual syntax required that we memorize or check the documentation carefully for the order of the inputs.
More generally, chaining methods has the following benefits and a few drawbacks:
Benefits:
- Conciseness: Code becomes shorter and easier to write, by reducing visual noise compared to repeating the object name.
- Readability: Chained methods create a fluent, human-readable structure that makes intent clear.
- Reduced Temporary Variables: There's no need to create intermediary variables, as the methods directly operate on the object.
Drawbacks:
- Debugging Difficulty: If one method in a chain fails, it can be harder to isolate the issue. It effectively prevents setting breakpoints, inspecting intermediate values, and identifying which method failed.
- Readability Issues: Overly long and dense method chains can become hard to follow, reducing clarity.
- Side Effects: Methods that modify objects in place can lead to unintended side effects when used in long chains.
Implementation
In the SimulationLauncher class, the method lauch performs the main operation, while the other methods just serve as parameter setters. They take the object as input and return the object itself, after modifying it, so that other methods can be chained.
classdef SimulationLauncher
properties (GetAccess = private, SetAccess = private)
years_
isDistributed_ = false;
template_ = 'TestTemplate';
priority_ = '+2';
memory_ = '+5000';
end
methods
function varargout = launch(obj)
% perform whatever needs to be launched
% using the values of the properties stored in the object:
% obj.years_
% obj.template_
% etc.
end
function obj = onYears(obj, years)
assert(isnumeric(years))
obj.years_ = years;
end
function obj = onDistributedCluster(obj)
obj.isDistributed_ = true;
end
function obj = withTemplate(obj, template)
obj.template_ = template;
end
function obj = withPriority(obj, priority)
obj.priority_ = priority;
end
function obj = withMemory( obj, memory)
obj.memory_ = memory;
end
end
end
As you can see, each method can be in charge of verifying the correctness of its input, independantly. And what they do is just store the value of parameter inside the object. The class can define default values in the properties block.
You can configure different launchers from the same initial object, such as:
launcher = SimulationLauncher();
launcher = launcher.onYears(2014:2020);
launcher1 = launcher ...
.onDistributedCluster() ...
.withReservedMemory('+6000');
launcher2 = launcher ...
.withTemplate('TmplProd') ...
.withPriority('+1') ...
.withReservedMemory('+7000');
If you call the same method several times, only the last recorded value of the parameter will be taken into acount:
launcher = SimulationLauncher();
launcher = launcher ...
.withReservedMemory('+6000') ...
.onDistributedCluster() ...
.onYears(2014:2020) ...
.withReservedMemory('+7000') ...
.withReservedMemory('+8000');
% The value of "memory" will be '+8000'.
If the logic is still not clear to you, I advise you play a bit with the debugger to better understand what’s going on!
Conclusion
I love how the method chaining technique hides the minute detail that we don’t want to bother with when trying to understand what a piece of code does.
I hope this simple example has shown you how to apply it to write and organise your code in a more readable and convenient way.
Let me know if you have other questions, comments or suggestions. I may post other examples of that technique for other useful uses that I encountered in my experience.
I’m currently developing a multi-platform viewer using Flutter to eliminate the hassle of manual channel setup. Instead of adding IDs one by one, the app uses your User API Key to automatically discover and list all your ThingSpeak channels instantly.
Key Highlights (Work in Progress):
- Automatic Sync: All your channels appear in seconds.
- Multi-platform: Built for Web, Android, Windows, and Linux.
- Privacy-Focused: Secure local storage for your API keys.
If you use tables extensively to perform data analysis, you may at some point have wanted to add new functionalities suited to your specific applications. One straightforward idea is to create a new class that subclasses the built-in table class. You would then benefit from all inherited existing methods.
One workaround is to create a new class that wraps a table as a Property, and re-implement all the methods that you need and are already defined for table. The is not too difficult, except for the subsref method, for which I’ll provide the code below.
Class definition
Defining a wrapper of the table class is quite straightforward. In this example, I call the class “Report” because that is what I intend to use the class for, to compute and store reports. The constructor just takes a table as input:
classdef Rapport
methods
function obj = Report(t)
if isa(t, 'Report')
obj = t;
else
obj.t_ = t;
end
end
end
properties (GetAccess = private, SetAccess = private)
t_ table = table();
end
end
I designed the constructor so that it converts a table into a Report object, but also so that if we accidentally provide it with a Report object instead of a table, it will not generate an error.
Reproducing the behaviour of the table class
Implementing the existing methods of the table class for the Report class if pretty easy in most cases.
I made use of a method called “table” in order to be able to get the data back in table format instead of a Report, instead of accessing the property t_ of the object. That method can also be useful whenever you wish to use the methods or functions already existing for tables (such as writetable, rowfun, groupsummary…).
classdef Rapport
...
methods
function t = table(obj)
t = obj.t_;
end
function r = eq(obj1,obj2)
r = isequaln(table(obj1), table(obj2));
end
function ind = size(obj, varargin)
ind = size(table(obj), varargin{:});
end
function ind = height(obj, varargin)
ind = height(table(obj), varargin{:});
end
function ind = width(obj, varargin)
ind = width(table(obj), varargin{:});
end
function ind = end(A,k,n)
% ind = end(A.t_,k,n);
sz = size(table(A));
if k < n
ind = sz(k);
else
ind = prod(sz(k:end));
end
end
end
end
In the case of horzcat (same principle for vertcat), it is just a matter of converting back and forth between the table and Report classes:
classdef Rapport
...
methods
function r = horzcat(obj1,varargin)
listT = cell(1, nargin);
listT{1} = table(obj1);
for k = 1:numel(varargin)
kth = varargin{k};
if isa(kth, 'Report')
listT{k+1} = table(kth);
elseif isa(kth, 'table')
listT{k+1} = kth;
else
error('Input must be a table or a Report');
end
end
res = horzcat(listT{:});
r = Report(res);
end
end
end
Adding a new method
The plus operator already exists for the table class and works when the table contains all numeric values. It sums columns as long as the tables have the same length.
Something I think would be nice would be to be able to write t1 + t2, and that would perform an outerjoin operation between the tables and any sizes having similar indexing columns.
That would be so concise, and that's what we’re going to implement for the Report class as an example. That is called “plus operator overloading”. Of course, you could imagine that the “+” operator is used to compute something else, for example adding columns together with regard to the keys index. That depends on your needs.
Here’s a unittest example:
classdef ReportTest < matlab.unittest.TestCase
methods (Test)
function testPlusOperatorOverload(testCase)
t1 = array2table( ...
{ 'Smith', 'Male' ...
; 'JACKSON', 'Male' ...
; 'Williams', 'Female' ...
} , 'VariableNames', {'LastName' 'Gender'} ...
);
t2 = array2table( ...
{ 'Smith', 13 ...
; 'Williams', 6 ...
; 'JACKSON', 4 ...
}, 'VariableNames', {'LastName' 'Age'} ...
);
r1 = Report(t1);
r2 = Report(t2);
tRes = r1 + r2;
tExpected = Report( array2table( ...
{ 'JACKSON' , 'Male', 4 ...
; 'Smith' , 'Male', 13 ...
; 'Williams', 'Female', 6 ...
} , 'VariableNames', {'LastName' 'Gender' 'Age'} ...
) );
testCase.verifyEqual(tRes, tExpected);
end
end
end
And here’s how I’d implement the plus operator in the Report class definition, so that it also works if I add a table and a Report:
classdef Rapport
...
methods
function r = plus(obj1,obj2)
table1 = table(obj1);
table2 = table(obj2);
result = outerjoin(table1, table2 ...
, 'Type', 'full', 'MergeKeys', true);
r = reportingits.dom.Rapport(result);
end
end
end
The case of the subsref method
If we wish to access the elements of an instance the same way we would with regular tables, whether with parentheses, curly braces or directly with the name of the column, we need to implement the subsref and subsasgn methods. The second one, subsasgn is pretty easy, but subsref is a bit tricky, because we need to detect whether we’re directing towards existing methods or not.
Here’s the code:
classdef Rapport
...
methods
function A = subsasgn(A,S,B)
A.t_ = subsasgn(A.t_,S,B);
end
function B = subsref(A,S)
isTableMethod = @(m) ismember(m, methods('table'));
isReportMethod = @(m) ismember(m, methods('Report'));
switch true
case strcmp(S(1).type, '.') && isReportMethod(S(1).subs)
methodName = S(1).subs;
B = A.(methodName)(S(2).subs{:});
if numel(S) > 2
B = subsref(B, S(3:end));
end
case strcmp(S(1).type, '.') && isTableMethod (S(1).subs)
methodName = S(1).subs;
if ~isReportMethod(methodName)
error('The method "%s" needs to be implemented!', methodName)
end
otherwise
B = subsref(table(A),S(1));
if istable(B)
B = Report(B);
end
if numel(S) > 1
B = subsref(B, S(2:end));
end
end
end
end
end
Conclusion
I believe that the table class is Sealed because is case new methods are introduced in MATLAB in the future, the subclass might not be compatible if we created any or generate unexpected complexity.
The table class is a really powerful feature.
I hope this example has shown you how it is possible to extend the use of tables by adding new functionalities and maybe given you some ideas to simplify some usages. I’ve only happened to find it useful in very restricted cases, but was still happy to be able to do so.
In case you need to add other methods of the table class, you can see the list simply by calling methods(’table’).
Feel free to share your thoughts or any questions you might have! Maybe you’ll decide that doing so is a bad idea in the end and opt for another solution.
I can't believe someone put time into this ;-)
Our exportgraphics and copygraphics functions now offer direct and intuitive control over the size, padding, and aspect ratio of your exported figures.
- Specify Output Size: Use the new Width, Height, and Units name-value pairs
- Control Padding: Easily adjust the space around your axes using the Padding argument, or set it to to match the onscreen appearance.
- Preserve Aspect Ratio: Use PreserveAspectRatio='on' to maintain the original plot proportions when specifying a fixed size.
- SVG Export: The exportgraphics function now supports exporting to the SVG file format.
Check out the full article on the Graphics and App Building blog for examples and details: Advanced Control of Size and Layout of Exported Graphics
No, staying home (or where I'm now)
25%
Yes, 1 night
0%
Yes, 2 nights
12.5%
Yes, 3 nights
12.5%
Yes, 4-7 nights
25%
Yes, 8 nights or more
25%
8 votes
Hi everyone
I've been using ThingSpeak for several years now without an issue until last Thursday.
I have four ThingSpeak channels which are used by three Arduino devices (in two locations/on two distinct networks) all running the same code.
All three devices stopped being able to write data to my ThingSpeak channels around 17:00 CET on 4 Dec and are still unable to.
Nothing changed on this side, let alone something that would explain the problem.
I would note that data can still be written to all the channels via a browser so there is no fundamental problem with the channels (such as being full).
Since the above date and time, any HTTP/1.1 'update' (write) requests via the REST API (using both simple one-write GET requests or bulk JSON POST requests) are timing out after 5 seconds and no data is being written. The 5 second timeout is my Arduino code's default, but even increasing it to 30 seconds makes no difference. Before all this, responses from ThingSpeak were sub-second.
I have recompiled the Arduino code using the latest libraries and that didn't help.
I have tested the same code again another random api (api.ipify.org) and that works just fine.
Curl works just fine too, also usng HTTP/1.1
So the issue appears to be something particular to the combination of my Arduino code *and* the ThingSpeak environment, where something changed on the ThingSpeak end at the above date and time.
If anyone in the community has any suggestions as to what might be going on, I would greatly appreciate the help.
Peter
